smetL a 
 
Class 
 Book. 
 
 
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 Copyright N?_ 
 
 COPYRIGHT DEPOSIT. 
 

Ube IRural Uext>Book Series 
 
 Edited by L. H. BAILEY 
 
 MANURES AND FERTILIZERS 
 
Z\)t Ifcural Efxt=i3ooR Series 
 
 Lyon and Fippin, Principles of Soil Man- 
 agement. 
 G. F, Warren, Elements of Agriculture. 
 
 A. R. Mann, Beginnings in Agriculture. 
 J. F. Duggar, Southern Field Crops. 
 
 B. M. Duggar, Plant Physiology, with 
 Special Reference to Plant Production. 
 
 G. F. Warren, Farm Management. 
 
 M. W. Harper, Animal Husbandry for 
 
 Schools. 
 E. G. Montgomery, The Corn Crops. 
 H. J. Wheeler, Manures and Fertilizers. 
 
MANURES AND FERTILIZERS 
 
 A TEXT-BOOK FOE COLLEGE STUDENTS AND A 
 
 WORK OE REFERENCE FOR ALL INTERESTED 
 
 IN THE SCIENTIFIC ASPECTS OF 
 
 MODERN FARMING 
 
 BY 
 
 HOMER J. WHEELER, Ph.D., D.Sc. 
 
 AGRICULTURAL CHEMICAL EXPERT OF THE AMERICAN AGRICULTURAL CHEMICAL 
 
 COMPANY AND FORMERLY PROFESSOR OF AGRICULTURAL CHEMISTRY 
 
 AND DIRECTOR OF THE AGRICULTURAL EXPERIMENT 
 
 STATION OF THE RHODE ISLAND 
 
 STATE COLLEGE 
 
 Neto If ork 
 
 THE MACMILLAN COMPANY 
 
 1913 
 
 All rights reserved 
 
 ; f> h 
 
S<b33 
 AN 5 
 
 Copyright, 1913, 
 Bt THE MACMILLAN COMPANY, 
 
 Set up and electrotyped. Published August, 1913. 
 
 Norton 00 $rass 
 
 J. 8. Cushing Co. — Berwick & Smith Co. 
 
 Norwood, Mass., U.S.A. 
 
 ©CI.A354 09 7 
 
PREFACE 
 
 The preparation of this volume was undertaken for the 
 purpose of meeting a distinct lack in collegiate agricultural 
 textbooks in the United States. It was hoped to prepare a 
 book reasonably free from extended details, such as are 
 found in certain of the larger foreign works, and likewise 
 to avoid the rather superficial treatment of the subjects 
 which has necessarily characterized many of the books 
 which have been written for the purpose of meeting the 
 earlier requirements of the American agricultural colleges, 
 and the present demands of agricultural high schools. The 
 intent has been to provide in a measure for the needs of the 
 graduate student in agriculture ; also for the requirements 
 of students in the agricultural colleges, teachers in agricul- 
 tural schools, graduates of agricultural schools and colleges, 
 agricultural institute lecturers, and the rapidly increasing 
 number of intelligent men who are daily interesting them- 
 selves in the scientific phases of modern farming. 
 
 In connection with the treatment of some of the newer 
 and more controversial phases of certain of the topics, au- 
 thorities have been cited freely, in order that the reader may 
 readily pursue the subjects further, if desired. These cita- 
 tions have been introduced at the bottom of the respective 
 pages, so as to permit of more convenient and ready ref- 
 erence than would be possible if they were placed at the 
 ends of chapters, or at the end of the volume. 
 
 Certain points have been referred to repeatedly in dif- 
 
vi PREFACE 
 
 ferent connections, in order that the reader may not have 
 his train of thought interrupted by frequent enforced refer- 
 ence to preceding pages or chapters. 
 
 The subject of guano and of human excrement will per- 
 haps be thought to have been treated too fully from the 
 historical standpoint, yet the agricultural teacher is ex- 
 pected to be conversant with such matters, and he can best 
 familiarize himself with them when they are being con- 
 sidered in their manurial relations. 
 
 Unusual attention has been paid to the sea-weeds of the 
 Atlantic coast for the reason that they are largely used 
 directly as fertilizers by the farmers, whereas those of the 
 Pacific coast, on account of their larger size, are now being 
 more generally utilized in a commercial way. The consid- 
 eration of sea-weeds is important, for notwithstanding that 
 they interest directly only a relatively small section of the 
 country, detailed information concerning them is not readily 
 accessible to those students who need it. 
 
 In the discussion of the dung of domestic animals, much 
 attention is given to the bacteria and other organisms in- 
 volved in its decomposition, for the reason that they greatly 
 affect its value under the varying conditions of moisture and 
 aeration. 
 
 Not only have organic nitrogenous manures been carefully 
 considered, but also the precautions necessary in determin- 
 ing their relative availability, and the results of such deter- 
 minations by different investigators. 
 
 The subject of nitrates and of ammonium salts has been 
 quite fully treated, especially from the standpoint of their 
 cumulative and indirect effects. The new synthetic nitrog- 
 enous fertilizers, calcium cyanamid and calcium nitrate, 
 have also received attention. 
 
 More than the customary amount of space has been devoted 
 to the subject of lime and its use, and magnesia, soda, and 
 
PREFACE Vll 
 
 manganese have been discussed more fully than in most of 
 the previous works of its kind. 
 
 Brief reference is made to the so-called catalytic fertilizers, 
 and to the effect of carbon disulfid, tricresol, toluene, and 
 other substances, certain of which are held to destroy soil 
 amebe and ciliates, and hence to promote unusual bacterial 
 development and ammonification. 
 
 Care has been taken to discuss the reasons for many of 
 the conflicting opinions on various subjects, in the belief 
 that those entering upon agricultural research work should 
 be taught to give such matters more careful consideration 
 than is frequently the case. 
 
 No apology is offered by the writer for the frequent refer- 
 ence to certain lines of research work at the Rhode Island 
 agricultural experiment station, for the reason that he can 
 speak of these results in a more authoritative way than of 
 work done elsewhere. Furthermore, the work has been, in 
 some respects, of a pioneer character, and has not been 
 duplicated. 
 
 In certain of the chapters matter will be found which is 
 of too theoretical a character to meet the needs of the casual 
 reader, and he is requested to pass it over charitably, remem- 
 bering that the prime object of this work is not to give rule- 
 of-thumb directions, but rather to aid in inculcating such 
 general principles as shall aid in making the student as 
 independent as possible of them, and at the same time fur- 
 nish a foundation upon which to base his future study of 
 the various relations of fertilizers and manures to soils and 
 crops. 
 
 As a matter of convenience to the vast majority of read- 
 ers, and because of the confusion incident to the use of the 
 names of the elements in place of phosphoric acid, potash, 
 soda, lime, and magnesia which are in common use through- 
 out the civilized world, the old and well-established nomen- 
 
Vlii PREFACE 
 
 clature has been retained, instead of following the lead of 
 one or two American writers who have seen fit to depart 
 from the universal custom. 
 
 Acknowledgments are due to the agricultural experiment 
 station of the Rhode Island State College for all of the 
 illustrations which have been used; likewise to Brooks, 
 Cameron, Deherain, Fritsch, Griffiths, Hall, Halligan, Hei- 
 den, Hilgard, Johnson, King, Murray, Lohnis, A. Mayer, 
 Miintz and Girard, Storer, Van Slyke, Voorhees, Vivian, and 
 others, whose works have been freely consulted ; also to Mr. 
 Wilcox, of Mystic, Conn., for details concerning the han- 
 dling of menhaden, to L. H. Bailey and P. B. Hadley for 
 helpful suggestions, and to my son, Carl 0. J. Wheeler, for 
 aid in reading the proofs. A debt of acknowledgment is 
 also recognized to Goessmann, Henneberg, Von Koenen, 
 V. Meyer, Th. Pfeiffer, Tollens, and Stockbridge, whose 
 work and teachings have been of fundamental assistance to 
 the author, as well as a source of lasting inspiration. 
 
 H. J. WHEELER. 
 May 12, 1913. 
 
CONTENTS 
 
 CHAPTER I 
 
 PAGES 
 
 Historical Introduction 1-9 
 
 Chemistry throws new light on the subject of manuring 
 
 — The views of Liebig — The early work of Lawes and 
 Gilbert — Assimilation of atmospheric nitrogen by plants 
 
 — Other facts established by Lawes and Gilbert — The 
 utilization of nitrates and guano — Employment of ammo- 
 nium salts — The manufacture and use of superphosphates 
 
 — The German potash salts — The manufacture of basic 
 slag meal — New processes for combining atmospheric nitro- 
 gen — New catalytic and other fertilizers. 
 
 CHAPTER II 
 
 Night Soil 10-18 
 
 Conservation of night soil now less necessary — Amount 
 of urine produced per person — Chemical composition of 
 human urine — The amount of solid excrement per indi- 
 vidual — Former methods of disposal in Europe were bad 
 
 — Orientals conserve human excrement carefully — The 
 conservation of human excrement in Paris — Poudrette 
 from human excrement — Treatment of excrement with 
 burned lime — The " A. B. C. " and other methods of con- 
 servation — The novel method of Sindermann — Repeated 
 use encourages undue leaf growth. 
 
 CHAPTER III 
 The Dung of Farm Animals and its Preservation . . 19-34 
 Influence of feed and age of animal on dung — Influence 
 of litter on manure — Collecting and caring for dung — 
 Horse manure — Cow manure — Sheep manure — Hog 
 
 ix 
 
X CONTENTS 
 
 PAGES 
 
 manure — Hen and pigeon manure — Amounts of litter 
 used as absorbents — Comparative absorbent power of 
 litters for water and ammonia — The degree of conserva- 
 tion effected by litters — Losses of manure lessened by 
 packing and trampling — Soil a powerful absorbent of am- 
 monia — Muntz and Girard's results on the absorption of 
 ammonia — The action of gypsum as a preservative of 
 manures — Keasons for using gypsum in excess — Gypsum 
 safe to use — Gypsum compared with other chemical pre- 
 servatives — Preservation by antiseptics. 
 
 CHAPTER IV 
 
 The Organisms and Fermentation of Dong . . . 35-54 
 The number of microorganisms present in cow and 
 horse manure — Significance of microorganisms in ma- 
 nure — Microorganisms in litter — Urine, when voided, 
 essentially free from microorganisms — The numbers 
 of bacteria decrease gradually — The disadvantage of 
 antiseptics — Types of microorganisms present in ma- 
 nure — Aerobic forms — Spore-forming anaerobic forms 
 — Actinomycetes — The yeasts — The molds and other 
 organisms — Animal organisms destroy bacteria — The 
 effect of heating and of antiseptics on manure — Destruc- 
 tive changes in the non-nitrogenous matter of dung — 
 Losses not confined to the cellulose — Most of the aerobic 
 and anaerobic organisms in dung are active — Diastatic 
 action — Decomposition of starch — Decomposition of pec- 
 tin — Decomposition of cellulose — Decomposition of fats 
 and waxes — Decomposition of urea — Decomposition of 
 hippuric acid — Changes produced in uric acid — Ammon- 
 ification of solid manure and litter — Terms used in dis- 
 cussing the decomposition of dung — The nature and cause 
 of the losses occurring in manure — Losses less by fer- 
 mentation when moist and compact — Losses increased by 
 bacteria from intestinal tract — Losses smaller in the later 
 stages of decomposition — Fresh manure lacks immediate 
 effectiveness — The great necessity of moisture in heaps of 
 solid manure — The preservation of the liquid manure. 
 
CONTENTS Xi 
 
 CHAPTER V 
 
 PAGES 
 
 The Practical Utilization of Manures .... 55-64 
 Storage versus direct application of manures — Immedi- 
 ate incorporation of manure with the soil — Losses occur- 
 ring in heaps in the field and if broadcasted — The time to 
 spread manure on fields — Certain vegetable substances aid 
 denitrification in manures — Losses by denitrification less 
 serious if used moderately — Other factors affecting losses 
 by denitrification — The lasting effect of stable manure — 
 Manure profitably supplemented by chemical fertilizers — 
 Factors governing the use of manure and chemicals — The 
 use of coarse manures — Reason for even spreading of 
 manure — Manure favors the disintegration of old sod. 
 
 CHAPTER VI 
 Sea-weeds 65-74 
 
 The value of sea-weed known to the ancients — Chemical 
 composition of sea- weeds — The composition varies at dif- 
 ferent seasons of the year — Sea- weed of chief importance 
 in New England — The value of eel-grass — Value limited 
 by distance of land — Practical utilization — Effect on the 
 quality of certain crops — Sea- weed quick in its action — 
 Sea- weed compared with farm-yard manures — Not a well- 
 balanced manure — Sea-weed as affecting the need of lime 
 — Freedom from weed seeds a great advantage — Com- 
 posting sea-weeds — Size and rapidity of growth of sea- 
 weeds. 
 
 CHAPTER VII 
 Guanos 75-85 
 
 Experimental trials of guano — Commercial introduction 
 into Europe — The general nature of guano — Chemical 
 composition of guanos — Chemical composition affected 
 by climatic conditions — Color and physical character — 
 Chincha Island guano — Significance of oxalic acid and 
 oxalates in guano — Influence on the physical character of 
 soils — The distribution and sources of guano — Adultera- 
 tion of guano — Rectified or dissolved guano — The man- 
 
Xll 
 
 CONTENTS 
 
 ner of vising guano — A poorly balanced manure — Bat 
 guano unlike Peruvian and other guanos — Appearance 
 of bat guano — Where found — Chemical composition — 
 Distribution — Precautions in the use and purchase of 
 bat guano — Bat guano needs supplementing. 
 
 CHAPTER VIII 
 
 Fish, Crab, Lobster, and Similar Wastes 
 
 Fish long used as a fertilizer — Early catching of fish 
 for fertilizer purposes — Special process for preparing 
 fish for fertilizer — Fish waste in Japan — In Newfound- 
 land — Norwegian wastes from cod and whales — Meth- 
 ods of handling menhaden in the United States — Fish 
 waste treated with sulphuric acid — Chemical composi- 
 tion and utilization of whale products — Availability and 
 use of fish guano — Requires supplementing — Fish scrap 
 may be employed without further treatment — Value of 
 fish waste depends on the climate and soil — Shrimps — 
 The king-crab — The common crab — Lobster refuse — 
 Star-fish. 
 
 CHAPTER IX 
 
 86-93 
 
 Common Slaughter-house Nitrogenous Waste Products 94-102 
 
 Dried meat meal — All readily utilized by fertilizer 
 manufacturers — Chemical composition of meat meal — 
 Availability of meat meal — The nature of bone tankage 
 — Composition of bone tankage — Value of bone tank- 
 age as a fertilizer — Method of employment — Chemical 
 composition of red dried blood — Chemical composition 
 of black dried blood — Reason for occasional low nitro- 
 gen content of blood — Chemical composition of the 
 better commercial blood — Crystallized blood — Certain 
 processes of preparing dried blood — Dried blood, if very 
 fine, is highly hygroscopic — Availability of blood de- 
 pendent upon soil conditions — Processes of preparing 
 horn meal and hoof meal — Chemical composition of 
 
CONTENTS Xlll 
 
 horn meal — Chemical composition of horn and hoof meal 
 — The nitrogen content of hoof meal — Efficiency of 
 hoof meal — Adulteration of horn and hoof meals — Pre- 
 paratory treatment of waste leather — The chemical 
 composition of prepared leather waste — The availability 
 of nitrogen in leather — Treatment of leather with car- 
 bonates of the alkalies — Leather really not so valuable 
 as it appears. 
 
 CHAPTER X 
 
 Other Miscellaneous Nitrogenous Substances . . 103-112 
 Feathers — Hair bristles and wool — Tannery hair — 
 Waste silk — Wastes from hares and rabbits — Chemical 
 composition of waste wool — Wool waste as a manure — 
 Effect of superheated steam on wool waste — Concern- 
 ing Petermann's tests of availability — Soluble wool waste 
 not subject to loss by leaching — Benefit from steaming 
 not equally applicable to all other nitrogenous wastes — 
 The value of garbage tankage low — Character of shoddy 
 and felt refuse — Chemical composition of shoddy 
 and felt — Use of felt and shoddy wastes as manures — 
 Character of soot — Chemical composition of soot — 
 Soot benefits physically — Soot rarely toxic — Light soot 
 best — Insects and cocoons — Peat and muck — Peat and 
 muck especially valuable on light soils — Salt and fresh 
 muds — Cereal and other seed by-products — Composition 
 of cotton-seed meal — Composition of linseed meal — 
 Composition of malt sprouts — Composition of castor 
 pomace — Composition of wet brewer's grains — Compo- 
 sition of gluten feeds — Utilization of the spent wash 
 of distilleries — The process of Vasseux — The process 
 of Effront. 
 
 CHAPTER XI 
 
 The Availability of Organic Nitrogen and Factors 
 
 Affecting it ....... 113-124 
 
 The factors of temperature and moisture — Effects on 
 the soil reaction — Effects of large applications at the 
 outset — Employment of different amounts of nitrogen 
 
XIV 
 
 CONTENTS 
 
 — Other elements must be supplied generously — False 
 conclusions a result of neglect of conditions — Results 
 by Eckenbrecher — Results by Kellner — Results by 
 Petermann — Precautions suggested by Wagner and 
 Dorsch — Results of tests by Wagner and Dorsch — Re- 
 sults by Wheeler and Hartwell — Results by Voorhees 
 
 — Results by Kellner on wet soil — Results by Seyffert 
 
 — Results by Heinrich — Results by Johnson — Results 
 by the nitrification method of Miintz and Girard — The 
 pepsin method — The permanganate method — Lipman's 
 ammonification method. 
 
 CHAPTER XII 
 
 Calcium and Potassium Nitrates ..... 
 Calcium nitrate a new fertilizer — Production possible 
 due to cheap electricity — The work of Lovejoy and 
 Bradley — The process of Birkeland and Eyde — First 
 product too hygroscopic — Processes for lessening hy- 
 groscopic tendency — Chemical composition — Calcium 
 nitrate as a fertilizer — Danger of the earlier products 
 injuring horses and workmen — Extent of the output of 
 calcium nitrate — Cost of producing calcium nitrate — 
 Other processes — Sources of potassium nitrate — 
 Artificial niter beds — Made for industrial purposes from 
 nitrate of soda — Potassium nitrate often economical for 
 agricultural use — Chlorin avoided by using potassium 
 nitrate. 
 
 CHAPTER XIII 
 
 125-131 
 
 Nitrate of Soda ........ 
 
 Sources of nitrate of soda — Concerning the origin of 
 the Chilian nitrate of soda — The first exploitation of 
 nitrate of soda — Chemical composition and purification 
 of nitrate of soda — Impurities of nitrate of soda — 
 Physical characteristics of nitrate of soda — The availa- 
 bility of nitrate of soda as plant food — Quantities to 
 apply and care in using — Nitrate of soda corrects soil 
 
 132-146 
 
CONTENTS XV 
 
 acidity — Physical effects of the residue from nitrate of 
 soda — The residual soda may liberate potash — Re- 
 sidual soda may replace potash in part — The soda of 
 nitrate of soda may in certain cases conserve the soil 
 potash — Soil improvement by using nitrate of soda — 
 Nitrate of soda may injure certain soils — Residual bene- 
 fit not due solely to hygroscopic effects — Soda as a car- 
 rier of phosphoric acid into plants — Nitrate of soda 
 conserves the lime supply of the soil — Nitrate of soda 
 not a stimulant — Yields quick returns on the manurial 
 investment — Possible effects on the microorganisms of 
 the soil — Ammonium nitrate — The synthetic produc- 
 tion of ammonia and ammonium salts. 
 
 CHAPTER XIV 
 
 Ammonium Salts and Calcium Cyanamid . . . 147-164 
 
 The manufacture of ammonium sulfate — Thiocya- 
 nates a former toxic impurity of ammonium sulfate — 
 Chemical composition of sulfate of ammonia — Sulfate 
 of ammonia must not be mixed with alkaline substances 
 — Absorption of sulfate of ammonia by soils — Its use 
 exhausts soils of lime — Nitrogen of sulfate of ammonia 
 fixed by microorganisms — Its efficiency as a fertilizer — 
 Soda important in trials of nitrate of soda and sulfate of 
 ammonia — Double decompositions follow the use of am- 
 monium salts — Partial soil sterility sometimes caused 
 by sulfate of ammonia — Conditions caused in acid soils 
 by sulfate of ammonia not fatal to all plants — Aids in 
 rendering certain grasses dominant — May cause the 
 suspension of certain bacterial activity — Sulfate of am- 
 monia liberates plant food — Ammonium salts fleeting in 
 their effects — Leach less quickly than nitrates — May 
 cause injury on light calcareous soils — Ammonia may 
 injure plants — Calcium cyanamid a new product — 
 Manufacture of calcium cyanamid — Changes in cal- 
 cium cyanamid resulting in the soil — Utilization for the 
 manufacture of urea and other substances — As a ferti- 
 
xvi CONTENTS 
 
 lizer — Practical difficulties connected with calcium cy- 
 anamid — The output of calcium cyanamid. 
 
 CHAPTER XV 
 
 Natural Phosphatic Fertilizers 165-190 
 
 Bone as a fertilizer — Chemical composition of bone 
 — Composition of the ash — Composition of weathered 
 bones — Treatment of bone for the removal of fat — 
 Effect of steaming on the nitrogen content — Bone wastes 
 from industries — Fermentation and other methods of 
 disintegrating bone — Bone meal as a fertilizer — The 
 soluble and reverted phosphoric acid of bone — Bone 
 tankage — Fish as a source of phosphoric acid — The 
 nature of floats — Soils on which to use floats — The ac- 
 tion of manure on floats — How floats should be used — 
 Liming in connection with the use of floats — Apatite 
 or phosphorite — Chemical composition and occurrence 
 of apatite — Wagnerite — Coprolites — Phosphatic 
 guanos — Nassau or Lahn phosphate — French, Belgian, 
 and Portuguese phosphates — The phosphates of Russia 
 and Northern Africa — The phosphates of South Caro- 
 lina — Florida phosphates — Tennessee phosphates — 
 Phosphates of the Western States — Occurrence and 
 composition of certain aluminum phosphates — Roasting 
 increases the efficiency of aluminum phosphates — The 
 solubility of artificial aluminum phosphates — Iron phos- 
 phates formed in soils — Solubility of artificial ferric 
 phosphate. 
 
 CHAPTER XVI 
 
 Manufactured Phosphates and Studies of Solubility 191-227 
 The manufacture of basic slag meal — Influence of 
 silica on the efficiency of basic slag — Range in composi- 
 tion of low and high grade basic slag — German methods 
 of determining availability — The degree of fineness — 
 Chemical composition of basic slag — The constitution 
 of basic slag — Practical use of basic slag meal — Care 
 in mixing basic slag with certain other materials — Arti- 
 
CONTENTS XV11 
 
 PAGES 
 
 ficial basic slag meal — Wiborgh phosphate — Wolter's 
 phosphate — Palmaer phosphate — Other artificial phos- 
 phates — The preparation of superphosphates — Treat- 
 ment of bone with small amounts of sulfuric acid — Free 
 phosphoric acid in superphosphates — Strictly chemical 
 use of the term "phosphoric acid" — The relationship 
 of the various phosphates — Care in the manufacture of 
 superphosphates — Practical process of making super- 
 phosphates — Double superphosphates — Dissolved bone 
 
 — Dissolved bone-black — Laboratory studies on the 
 solubility of phosphates — The action of water on mono- 
 calcium phosphate — The action of water on dicalcium 
 phosphate — The action of water on tricalcium phosphate 
 
 — Determination of "soluble" phosphoric acid — Ad- 
 vantages of soluble phosphoric acid — The reversion of 
 monocalcium phosphate — Liming after reversion with 
 iron and aluminum oxids — The determination of re- 
 verted phosphoric acid — Reverted phosphoric acid not 
 all from dicalcium phosphate — The term available phos- 
 phoric acid — Insoluble phosphoric acid — The reversion 
 of monocalcium phosphate — Reversion often beneficial 
 in some respects — Reversion with iron and aluminum 
 oxids serious — Reversion as affected by pyrite — The 
 fixation of superphosphates in soils rapid — Fixation of 
 phosphates confined chiefly to the surface soil — Availa- 
 bility of fixed phosphates may still be high — Injury from 
 applications of superphosphates rare — Soils on which 
 superphosphates may give poor results — Superphos- 
 phates have a flocculating action on soils — Various soil 
 conditions affecting the choice of phosphates to be used 
 
 — Crops and conditions for which superphosphates are 
 especially adapted. 
 
 CHAPTER XVII 
 
 Potassic Fertilizers 228-245 
 
 "Wood ashes and lime-kiln ashes — Cotton-seed hull 
 ashes — Saltpeter waste — Other wastes containing pot- 
 ash — Potash from sea-weeds and other plants — Anal- 
 
xviii ' CONTENTS 
 
 yses of sea-weeds — Tobacco stems — Indian corncobs 
 — Potassium nitrate — Potassium carbonate — History of 
 the German potash deposits — Americans buy a German 
 potash mine — The famous potash contracts — Mode of 
 occurrence and distribution of potash deposits in Europe 
 
 — Chemical composition of the more important potash 
 salts — Duration of the deposition of potassium salts — 
 Natural deposits of potassium salts elsewhere — Kainit 
 
 — Sylvanit and carnallit — Muriate of potash — High- 
 grade sulfate of potash — Double sulfate of potash and 
 magnesia, or double manure salt — Double carbonate of 
 potash and magnesia — Silicate of potash — Potassium 
 carbonate (pearl ash) — Greensand — Phonolite, nephe- 
 line, alunite, leucite, and feldspars as sources of potash. 
 
 CHAPTER XVIII 
 
 The Theory and Practice of Potash Fertilization . 246-260 
 The alleged ill effects of the chlorin of potassium and 
 other salts — Reasons for the diversity of ideas concern- 
 ing chlorids — Use of chlorids increases the need of 
 liming — The fate of sulfate of potash in the soil — Con- 
 cerning the retention of potash by soils — Teachings of 
 the Rothamsted investigations — Various factors affect- 
 ing absorption — Potassium essential to plant growth — 
 Potassium aids carbohydrate foi'ination — Other func- 
 tions of potassium — Potassium increases the size of the 
 individual grains of cereals — Effect of potassium on 
 photosynthesis — Potassium in connection with turgor 
 
 — Functions of potassium not necessarily shown by re- 
 sults which its absence produces — Potassium as a neu- 
 tralizer and carrier within the plant — Potassium may 
 contribute to the "luxury consumption" of plants — 
 Certain functions and effects of potassium salts in soils 
 ■ — Effect of potassium salts on legumes — Effect of a 
 lack of potassium on grasses and other plants — Potas- 
 sium salts act best in wet seasons — Lack of potassium 
 more serious for some crops than for others — Potash 
 conservation in the soil by sodium salts. 
 
CONTENTS XIX 
 
 CHAPTER XIX 
 
 PAGES 
 
 Lime and its Relation to Soils and Fertilizers . . 261-294 
 The occurrence of lime — Distribution and effect 
 of limestone — Kinds of lime used in agriculture 
 — The effect of lime on nitrogen availability — The 
 effect of lime on denitrification — The effect of lime on 
 soil texture — The use of lime in connection with phos- 
 phates — Lime as a destroyer of worms and slugs — 
 Need of liming suggested by soil acidity — Liming the 
 most economic basic treatment — Chemical methods for 
 determining the lime requirements of soils — Effect of 
 lime on vegetable decay — Effect of lime on nitrogen 
 content of humus — Rational rotation and the turning 
 under of sward should accompany liming — Avoidance 
 • of liming to conserve humus, not wise — Carbonate of 
 lime versus slaked or burned lime — The penetration of 
 lime into soils — Expulsion of ammonia from soils as a 
 result of liming — Influence of lime on nitrification — 
 Effect of calcium and magnesium carbonates on ammon- 
 ification — General ideas as to the indirect manurial 
 action of lime — -Results with sodium and magnesium 
 salts illustrate how lime acts indirectly — Fixation of 
 potash after liberation by lime — Caustic lime attacks 
 powdered quartz — Losses of lime by leaching — Coarsely 
 ground limestone compared with fine limestone and marl 
 — Concerning the practical use of lime — Pure lime com- 
 pared with magnesian lime. 
 
 CHAPTER XX 
 
 Liming in its Relation to Plants 295-308 
 
 Plants may transform lime compounds — Miscellane- 
 ous effects of lime on plant diseases — Lime in connec- 
 tion with potato scab — Lime may be used and potato 
 scab avoided — Lime may cause injury to pineapples — 
 Effect of lime on the size of potatoes — Liming may 
 hasten crop maturity — Soils needing liming for some 
 plants ideally adapted to others — Details concerning 
 the lime requirements of different plants. 
 
XX 
 
 CONTENTS 
 
 CHAPTER XXI 
 
 Gypsum and Waste Lime from Industries 
 
 Early use of gypsum — Source of some of the gypsum 
 in soils — Gypsum poorer than lime on acid soils — Gyp- 
 sum may yield calcium carbonate in the soil — Gypsum 
 may furnish lime or sulfur as plant food — Factors de- 
 termining the choice between gypsum and lime — Gyp- 
 sum as a retainer of ammonia — Methods of applying 
 gypsum — Gypsum as an oxidizing agent — Gypsum may 
 sometimes aid nitrification — Gypsum a renovator of 
 alkaline soils — Effect of gypsum on the solubility of 
 lime — Gas-lime and lime from other industries. 
 
 PAGES 
 
 309-315 
 
 CHAPTER XXII 
 
 Magnesia as a Fertilizer ...... 316-332 
 
 Functions of magnesia in plants — Conflicting ideas as 
 to the action of magnesia — Loew's theory concerning 
 magnesia — Ratios of lime and magnesia in different 
 soils — Variations in magnesia content of different parts 
 of the same plant — Concerning the alleged toxic action 
 of magnesium chlorid — Danger from using caustic mag- 
 nesia and burned and hydrated magnesian lime — Solu- 
 bility of magnesium carbonate in its relation to practice 
 and experiment — Ranges in lime and magnesia content 
 of plants without material difference in yield — Desirable 
 lime and magnesia ratios in soils and culture solutions 
 — Sources of magnesia. 
 
 CHAPTER XXIII 
 
 Sodium Salts 333-350 
 
 Mineral sources of sodium salts — Black alkali — Quan- 
 tities of common salt injurious to crops — The presence of 
 soda in plants — Sodium salts as indirect manures — 
 Concerning the benefit to crops from applying sodium 
 salts — The effect of sodium salts dependent on various 
 conditions — Influence of sodium salts on the conserva- 
 tion and movement of soil moisture — The effect of 
 sodium salts on osmotic pressure — The possible phys- 
 
CONTENTS Xxi 
 
 PAGES 
 
 iological and manurial functions of sodium salts — Re- 
 sults by Jordan and Genter — Soda in connection with 
 diastatic action — Atterberg's experiments with soda — 
 Experiments at Bernburg, Germany — The Rhode Island 
 experiments — Practical significance of soda in agri- 
 culture. 
 
 CHAPTER XXIV 
 
 Iron and Manganese 351-356 
 
 Iron in its relation to plant growth — Manganese in 
 plants and soils — Manganese as a fertilizer — Manganese 
 in Hawaiian soils — Plants unlike in endurance of manga- 
 nese — Variations in manganese content of plants — 
 Effect of manganese on enzymes — Manganese increases 
 many crops — Roots change the oxidation of manganese 
 
 — Manganese may aid chlorophyl development. 
 
 CHAPTER XXV 
 
 Chlorin, Sulfur, Silica, Carbon Disulfid, Toluene, 
 
 and Other Miscellaneous Substances . . . 357-366 
 
 Chlorin — Sulfur — Sulfur may become depleted in 
 soils — Relation of sulfur and phosphorus in plants and 
 soils — Need of sulfur should be investigated — Silica in 
 plants — Suggested functions in plants — Silica may re- 
 place other ingredients in the " luxury consumption " — 
 Silica deposition checks sap diffusion — Carbon disulfid 
 often increases crops — Reasons suggested for the benefit 
 to soil from using carbon disulfid — Treatment of soils 
 with carbon disulfid costly — Carbon disulfid cures cer- 
 tain vetch, clover and alfalfa "sick" soils — Carbon 
 disulfid not the only unusual compound to benefit soils 
 
 — Disinfectants, like heating, destroy soil amebe — De- 
 struction of soil protozoa may explain benefit from soil 
 "firing" and deep plowing — General applicability of 
 soil disinfection doubted by Loew — The chlorid of lime 
 treatment of soil tried by Loew. 
 
 Index 
 
 367 
 
FERTILIZERS 
 
 CHAPTER I 
 
 HISTORICAL INTRODUCTION 
 
 According to the earlier conception of the term 
 "'manure," it meant anything which when applied to 
 the soil will render it more productive. In fact, certain 
 very early English writers referred to the benefits of 
 tillage as a manuring of the land. 
 
 The use of the dung of animals, and of chalk, marl, 
 wood-ashes, and certain other substances for increasing 
 the productivity of the soil, was known not only to the 
 early Greeks and Romans but apparently also to the 
 Chinese, whose employment of them for such purposes 
 probably far antedates all human records. 
 
 Indeed, Mago, the king of Carthage, in his work on 
 agriculture, which won for him from his enemies, the 
 Romans, the designation "Father of Agriculture," wrote 
 of the value of bird manure, praising especially that of 
 pigeons, and Cato (born 234 B.C.), the first Roman agri- 
 cultural writer, gave to bird manure the first place. 
 
 The manurial effect of various miscellaneous substances, 
 and of certain legumes, was also well recognized not only 
 by the agricultural writers Varro (39 B.C.) and Columella 
 (50 a.d.), but even by the poet Virgil, for the latter, in 
 speaking of ashes and dung, says : — 
 
 " But sweet vicissitudes of rest and toil make easy labor, and 
 renew the soil. 
 
 " Yet sprinkle sordid ashes all around, and load with fattening 
 dung the fallow ground." 
 
 b 1 
 
2 ' FERTILIZERS 
 
 During the dark ages, following the decline of the 
 Roman Empire, practically all records of the use of lime 
 and of other manures are lacking. The knowledge of 
 their value was, however, presumably perpetuated by the 
 studious inmates of the monasteries. Already in the 
 sixteenth century a revival of the knowledge of manuring 
 had begun, as shown by the writings of Bernard Palissy. 
 
 Even Jethro Tull, the early English writer who con- 
 tended that manures are unnecessary if the land is suffi- 
 ciently tilled, was hardly more radical in his day than a 
 certain recent writer who asserted that the chief func- 
 tion of fertilizers was to improve the physical condition, 
 and later, that it was to render innocuous various toxins 
 of the soil. 
 
 1. Chemistry throws new light on the subject of manur- 
 ing. — A true understanding of the fundamental princi- 
 ples of manuring was made possible only through the 
 aid of chemistry, although more or less general specula- 
 tion on the subject had long existed, a fact well illustrated 
 by many of the earlier English agricultural writings. 
 
 One of the first steps toward a rational understanding 
 of the problems of plant nutrition was the discovery by 
 Priestley, in 1772, that combustion and the respiration of 
 animals deteriorate the air and lessen its volume, but 
 that plants can render it again capable of supporting com- 
 bustion. This observation, coupled with his discovery of 
 oxygen, led to the recognition of the fact that the bubbles 
 already observed by Bonnet on leaves when they were 
 immersed in water, were chiefly oxygen. It was then 
 shown by Ingenhaus that these phenomena were caused 
 by the action of sunlight, and Sennebier established the 
 fact that the oxygen evolved by plants resulted from the 
 decomposition of the carbon dioxicl already taken up from 
 
HISTORICAL INTRODUCTION 3 
 
 the air, a fact demonstrated in a quantitative way by 
 De Sassure. The last investigator showed that carbon, 
 associated with the elements of water in the proportions 
 represented by carbohydrates, such as starch and sugar, 
 constitute the chief weight of plants. It was De Sassure, 
 likewise, who recognized nitrogen as a plant constituent, 
 and also the source and value of the ash ingredients. He 
 supposed that the element nitrogen was derived either 
 from the organic constituents of the soil or from ammonia 
 present in the air. The idea that the ash constituents are 
 of special value to the plant was also held by Sir Humphrey 
 Davy. 
 
 Several writers, including Thaer, added their contribu- 
 tions to the accumulated knowledge of plant nutrition; 
 but it remained for Boussingault to make the first syste- 
 matic field experiments. His carefully conducted re- 
 searches substantiated the accumulation of far more 
 carbon in the plants than could have been derived from 
 the soil. He also showed that more nitrogen was removed 
 in the crops than was supplied in the manure. 
 
 2. The views of Liebig. — Notwithstanding the inves- 
 tigations of those who had preceded him, Justus von 
 Liebig soon became the great central agricultural figure, 
 for in 1840 he maintained that if plants are supplied with 
 the small quantity of mineral constituents of the ash, the 
 remainder of their substance can be drawn from the air. 
 
 It appears that Liebig was in error concerning the 
 equal importance of the elements of the ash, also as con- 
 cerns the analysis of the ash being a safe guide in manuring, 
 and in respect to the mode of assimilation of the nitrogen. 
 He also erred as to the possibility of certain elements 
 replacing others which were somewhat similar, as, for 
 example, in the supposed possibility of the complete 
 
4 FERTILIZERS 
 
 replacement of potassium by sodium. It is now of interest 
 to note, however, that the latest researches on this subject 
 by Wilfarth and his co-workers in Germany, and by 
 Wheeler and Hartwell and their co-workers in Rhode 
 Island, uphold the idea of the partial replacement of 
 potassium by sodium, in connection with the whole or a 
 part of some one or more of its functions in the case 
 of at least certain classes of plants. Another question 
 concerning which Liebig was gravely in error was that of 
 the nitrogen supply of plants. He supposed, with others, 
 that the amount of ammonia in the air was much greater 
 than is actually the case, and that this supply was main- 
 tained or even augmented with great practical benefit 
 by the ammonia escaping into the air in the course of 
 the fermentation of nitrogenous manures. It was in 
 fact in this way that Liebig supposed that such manures 
 were helpful to plants. 
 
 3. The early work of Lawes and Gilbert. — Many of the 
 views expounded by Liebig were discredited by John Ben- 
 nett Lawes (later knighted) of Rothamsted, England, who 
 made a number of experiments on his own account. 
 
 When in 1843 John Bennett Lawes associated with 
 himself Dr. Joseph Henry Gilbert, a former student of 
 Liebig's, he took the first great step in systematic agri- 
 cultural experimentation by the establishment of the 
 Rothamsted experiment farm, upon which they conducted 
 the painstaking researches which have become classic 
 in the annals of agriculture. The subsequent experi- 
 ments at Rothamsted, in which the American, Pugh 
 (afterwards President of the Pennsylvania State College), 
 was associated, appeared to disprove the supposed assim- 
 ilation of atmospheric nitrogen which Ville and others 
 believed to have observed. In fact, in the course of the 
 
HISTORICAL INTRODUCTION 5 
 
 experiments at Rothamsted in which the soil was sterilized, 
 without thought of the consequences, it was concluded 
 that the gain in nitrogen by legumes was due merely to 
 their great feeding range by virtue of sending their roots 
 so deeply into the soil, — a conclusion which for several 
 years received world-wide acceptance. 
 
 4. Assimilation of atmospheric nitrogen by plants. — 
 Notwithstanding the general acceptance of the idea that 
 plants could not assimilate nitrogen directly from the air, 
 the fact was nevertheless shown by Atwater l in 1884 in 
 experiments with peas, which were grown in unsterilized 
 soil in pots under such conditions that subsoil was elimi- 
 nated, and not only all of the nitrogen of the soil, 
 seed, and fertilizers was known, but also the nitrogen 
 in the resulting plants could be determined definitely. 
 Similar experiments were in progress at the same time by 
 Hellriegel and Wilfarth 2 at Bernburg, Germany, which 
 supported fully the conclusions of Atwater. The German 
 investigators went indeed far beyond all who had preceded 
 them and, by a series of experiments extending over a" 
 period from 1883 to 1888, established the fact that such 
 assimilation of atmospheric nitrogen is due to the inter- 
 vention of microorganisms existing in symbiotic relation- 
 ship in the nodules on the roots of certain legumes. It 
 has since been shown that even a few plants belonging to 
 other families, as, for example, the alder, also assimilate 
 atmospheric nitrogen. 
 
 5. Other facts established by Lawes and Gilbert. — The 
 honor nevertheless belongs to Lawes and Gilbert of estab- 
 lishing the dependence of many of the common agricul- 
 
 1 Am. Chem. Jour., 6 (1884-1885), pp. 365-388. 
 
 2 Untersuchungen iiber die Stickstoffnahrung der Gramineen und Le- 
 guminosen, Berlin, 1888. 
 
6 ' FERTILIZERS 
 
 tural plants on a supply of combined nitrogen, — a fact 
 confirmed by the close relationship of the yields to the 
 quantities of this element added in available form to the 
 soil. It had been held, on the contrary, by Liebig that 
 certain very leafy plants, represented by the common 
 root-crops and clover, can flourish independently of 
 nitrogenous manures (a fact since established for the 
 clovers), and are able to draw their supply from the nitro- 
 gen of the air. The field experiments of Lawes and 
 Gilbert also demonstrated the prime importance of potash 
 and phosphoric acid as manures, in contrast with the other 
 constituents of the plant ash. These conclusions were of 
 fundamental importance to agriculture and paved the way 
 for the development of the present enormous fertilizer 
 industry. Other experiments in progress at the same 
 time by Boussingault, Stohmann, and Knop on the growth 
 of plants in various nutrient solutions supplemented the 
 work at Rothamsted and placed the question of plant 
 nutrition on a substantial and scientific basis. 
 
 It is an interesting fact that by this work of various 
 investigators in the preceding century there was afforded 
 the first satisfactory explanation of the beneficial effect 
 following the addition to the soil of a whole series of waste 
 nitrogenous materials and substances of other kinds, the 
 utilization of which, in connection with crop production, 
 was recorded in England as early as 1653, and had no 
 doubt been known already for many centuries. 
 
 6. The utilization of nitrates and guano. — The im- 
 portation of nitrate of soda and of Peruvian guano into 
 England for manurial purposes was begun about 1838 
 and 1840 respectively, although the value of nitrate of 
 potash in connection with the growth of crops was surely 
 known as early as 1669. 
 
HISTORICAL INTRODUCTION 7 
 
 7. Employment of ammonium salts. — The ammonium 
 salts were supposedly first employed as manures as a 
 result of the work and writings of De Sassure and Liebig 
 on the utilization of ammonia by plants. Their use by 
 Lawes, however, antedates the appearance of Liebig's 
 memorable paper on the subject in 1840. The systematic 
 trials of a mixture of ammonium chlorid and of ammonium 
 sulfate at the Rothamsted experiment station date from 
 the year 1843. 
 
 8. The manufacture and use of superphosphate. — 
 The employment of mineral phosphates, in a limited way, 
 was begun in 1842 when Lawes took out his patent for 
 the manufacture of superphosphate, but they were not to 
 be had in any considerable quantity until three years 
 later, when coprolites were discovered in England. 
 
 9. The German potash salts. — It is a noteworthy 
 fact that the common salt manufacturers in certain parts 
 of northern Germany were long troubled by supposedly 
 worthless materials consisting of mixtures of crystalline 
 salts of potassium chlorid, potassium sulfate, and corre- 
 sponding salts of calcium and magnesium which were 
 associated with some common salt and were found over- 
 lying the purer rock-salt deposits. These materials were 
 considered so objectionable and they interfered so se- 
 riously with the common salt manufacture that they were 
 given the collective name of " Abraumsalz," which desig- 
 nates something to be taken out of the way. In or about 
 the year 1860, however, the use of these salts for agri- 
 cultural purposes was begun, — a step which has led to the 
 present enormous output of kainit, muriate of potash, 
 double manure salt (chiefly sulfate of potash and sulfate 
 of magnesia), and of high-grade sulfate of potash, the 
 
8 FERTILIZERS 
 
 world's supply of which practically all comes at present 
 from the German mines. 
 
 10. The manufacture of basic slag meal. — Another 
 notable advance in the development of the fertilizer in- 
 dustry resulted from the discovery in 1879 by Thomas and 
 Gilchrist, in England, of a method by which phosphatic 
 iron ore could be effectively freed of its phosphorus in 
 connection with the Bessemer process for the manufacture 
 of steel, and whereby the resulting phosphatic slag was 
 transformed into a valuable fertilizer. It has been stated 
 that the same process was discovered independently by 
 Jacob Reese in the United States. This phosphatic by- 
 product is known under the names " Thomas phosphate," 
 " Thomas meal," " basic slag meal," and the like. The 
 use of this material has already reached enormous pro- 
 portions in Europe, and it is being exported in considerable 
 quantities to America, Egypt, and elsewhere. 
 
 11. New processes for combining atmospheric nitrogen. 
 — Another important advance in 'the fertilizer industry 
 has been brought about by the recent discovery by Frank 
 and Caro, of Berlin, Germany, of commercially successful 
 methods for. the manufacture of calcium cyanamid by 
 the utilization and combination of atmospheric nitrogen 
 through the agency of calcium carbide. 
 
 A still further step in advance in connection with the 
 nitrogen fertilizer problem has resulted as a consequence 
 of the discovery of a method by Berkeland and Eyde by 
 which, by the aid of a powerful electric current, atmos- 
 pheric nitrogen can be combined and united with calcium 
 to form calcium nitrate. In Germany a process has also 
 been devised by which hydrogen and nitrogen gases are 
 made to unite under pressure and form ammonia by the 
 aid of catalytic agents. 
 
HISTORICAL INTRODUCTION 9 
 
 12. New catalytic and other fertilizers. — Space will 
 not permit the mention of the many other new processes 
 for the treatment of low-grade crude phosphates, feldspar, 
 and similar materials, in order to increase their avail- 
 ability, and of the series of so-called catalytic fertili- 
 zers, such as certain manganese and zinc salts. 
 
 Whereas it has seemed with each new discovery that 
 the limit of human invention and accomplishment might 
 have been reached, the recent progress doubtless only 
 foreshadows still greater steps in the immediate future. 
 
CHAPTER II 
 
 NIGHT SOIL 
 
 The term " night soil " has long been applied to human 
 excrement for the reason that it was often customary, 
 before the introduction of sewers, to remove it from 
 cities and towns during the night. 
 
 Human excrement is exceptionally rich in nitrogen 
 and phosphoric acid. This is due not only to the nature 
 of the food consumed, but also to the high degree of diges- 
 tibility of the non-nitrogenous constituents of the diet, 
 as compared with the coarser feeds consumed by the do- 
 mestic animals. By the fermentation of the excrement 
 great losses of nitrogen may result. 
 
 13. Conservation of night soil now less necessary. — 
 Owing to the rapid consumption of the natural supply of 
 nitrate of soda, the fear was expressed quite recently 
 that through the drain upon the land occasioned by the 
 great numbers of people living in cities, and the almost 
 universal waste of their excrement in the sewage, a 
 nitrogen famine might result. Fortunately, this fear 
 has been dispelled by the more recent discovery of 
 economical methods for the production of calcium 
 cyanamid, calcium nitrate, and ammonia from the in- 
 exhaustible supplies of limestone, atmospheric nitrogen, 
 and hydrogen. 
 
 Danger to health. — One of the great objections to the 
 use of human excrement as a manure is that it is often a 
 
 10 
 
NIGHT SOIL 11 
 
 great source of danger, on account of its being a ready 
 medium for the conveyance of the organisms which 
 cause various types of human disease. The necessity 
 of providing a safe place for the deposition of human 
 excreta at a distance from the abiding place of man, 
 is even set forth in the Bible Deuteronomy 23, verses 
 12 and 13). 
 
 14. Amount of urine produced per person. — Ac- 
 cording to Heiden, a single individual produces in the 
 course of the year about 1000 pounds of excrement, 
 having a usual fertilizing value of from two to three 
 dollars. 
 
 It was found by Lecanu, in experiments with sixteen 
 persons of different ages and sexes, that the excretion of 
 urine, per twenty-four hours, ranged from 525 to 2271 
 grams. In experiments conducted on himself, Lehmann 
 found, in a fourteen-day test with a mixed diet, that the 
 daily excretion of urine amounted to from 879 to 1384 
 grams ; and in the course of a twelve-day vegetable diet, 
 it fell to from 720 to 1212 grams. Based upon these and 
 other data, it is probably safe to estimate the average daily 
 excretion of urine, per capita, at about 1200 grams (about 
 4.2 pounds). 
 
 The solid matter in human urine has been found, based 
 upon the work of several investigators, to range from about 
 34.5 to 87.4 grams per day, though it is said to vary with 
 the different nationalities. This variation may, however, 
 be due to temperature and other climatic conditions, 
 rather than to constitutional differences. 
 
 15. Chemical composition of human urine. — The 
 following percentages, given by Lehmann, represent the 
 relative quantities of some of the more important con- 
 stituents of human urine : — 
 
12 
 
 FERTILIZERS 
 
 With a mixed diet . . 
 With an animal diet 
 With a vegetable diet . 
 With a nitrogen-free diet 
 
 Urea 
 
 Uhic 
 Acid 
 
 32.5 
 53.2 
 22.5 
 15.4 
 
 1.18 
 1.48 
 1.02 
 0.74 
 
 Extractive 
 Substances 
 and Salts 
 
 12.8 
 
 7.3 
 
 19.2 
 
 17.1 
 
 It appears therefore that the urine varies greatly in com- 
 position, as well as in amount, according to the diet of 
 the individual. 
 
 It has been found that the percentage of nitrogen in the 
 urine of children eight months old is about 0.15; in that 
 of men 21 years old, 1.02, and in the urine of men of 46 
 years, 1.57 to 1.84. Based upon an average of 1200 grams 
 of urine per twenty-four hours per individual, the average 
 daily excretion of nitrogen in the urine would amount to 
 13.36 grams. 
 
 The quantity of non-combustible salts is least in the 
 urine of children, followed in turn by the urine of women, 
 aged people, and men. The variations, however, in indi- 
 vidual cases, and within these groups are very great. The 
 chief constituents of the ash of urine, named in order, are 
 chlorin, soda, potash, phosphoric acid, sulfuric acid, 
 lime, magnesia, and iron oxid. Slight amounts of in- 
 soluble matter make up the remainder. 
 
 16. The amount of solid excrement per individual. — 
 The average quantity of solid excrement, per day, as 
 found by Lawes and Gilbert, for boys under sixteen years 
 of age, was about 108 grams ; for men between 16 and 50 
 years, it was about 152 grams ; and for men over 50 years 
 of age, about 226 grams. The dry substance ranged 
 
NIGHT SOIL 
 
 13 
 
 from 27.4 to 42.3 per cent ; it was found to be greatest 
 in the case of old men. The amount of nitrogen present 
 in the average daily excretion of the solid excrement of 
 boys was 2.34 grams, of men 1.94 grams, and of old men, 
 0.321 gram. The quantities of ash were 3.69, 4.23, and 
 8.32 grams, respectively. In the ash the phosphoric acid 
 has been found to range from about 31 to 43 per cent, 
 the potash from about 6 to 21 per cent, lime from about 
 17 to 27 per cent, and magnesia from about 10.5 to 15.5 
 per cent. 
 
 Heiden gives the following as the average quantity of 
 both solid and liquid excrement per person daily : — 
 
 Total quantity 
 
 Solid matter ..."... 
 
 Organic matter 
 
 Nitrogen (in organic matter) 
 
 Ash . 
 
 Phosphoric acid (in ash) . . 
 Potash (in ash) 
 
 Solid 
 Grams 
 
 Liquid 
 Grams 
 
 133.0 
 
 1200.0 
 
 30.3 
 
 64.0 
 
 25.9 
 
 50.0 
 
 2.1 
 
 12.1 
 
 4.5 
 
 13.0 
 
 1.6 
 
 1.8 
 
 0.7 
 
 2.2 
 
 Total 
 Grams 
 
 1333.0 
 94.0 
 75.5 
 14.2 
 17.5 
 3.4 
 3.0 
 
 17. Former methods of disposal in Europe were bad. — 
 In Europe, generally, the conditions connected with the 
 disposal of human excrement were, until a comparatively 
 recent period, extremely bad, and even after the construc- 
 tion of sewers emptying into the most accessible streams, 
 the situation became highly dangerous to the public 
 health. In England this led to the appointment of a 
 special commission to inquire into, and report concerning, 
 the matter. As a result of this and of similar agitation in 
 
14 FERTILIZERS 
 
 other lands, the present efficient septic tank and combined 
 precipitation and filtration systems have been evolved. 
 
 18. Orientals conserve human excrement carefully. — 
 Japan and China have thus far led the world in the 
 systematic saving and use of human excrement for agri- 
 cultural purposes. It has been possible thereby in the 
 past, not only to maintain the enormous population of 
 those countries, which is five to six times as dense as that 
 of certain of the chief countries of Europe, but they have 
 also been able, since the opening of their ports, to export 
 to other countries considerable amounts of human food. 
 In view of the practical economies of the Oriental nations 
 in this respect ; and in view of the fact that the world 
 seemed to be facing a future nitrogen famine, many sys- 
 tems for the preservation of human excrement have 
 been devised from time to time. Owing, however, to 
 the present methods of transforming the inexhaustible 
 nitrogen supply of the air into available plant food in an 
 economical way, it is unnecessary to devote space here to 
 their description, from the standpoint of the conservation 
 of nitrogen, more than by way of the briefest historical 
 reference. 
 
 19. The conservation of human excrement in Paris. — 
 The first police ordinance of the city of Paris, relating to the 
 disposition of human excrement in a secret vault or similar 
 place in each house, dates from 1348, but it was not until 
 1583 that a penalty for such an omission was provided. 
 Regulations for the construction of such receptacles were 
 made in 1809 by a decree of Napoleon, which was renewed 
 in 1819. 
 
 From 1781 to 1849 the human excrement of the city of 
 Paris was deposited in an abandoned suburban quarry 
 from which source the offensive odors penetrated a con- 
 
NIGHT SOIL 15 
 
 siderable portion of the city. As a result, provision was 
 finally made for its disinfection and for effecting a separa- 
 tion of the liquid and solid excrement. The former was 
 then conducted into cisterns just outside of the city, from 
 whence it was pumped to a more distant point, to which 
 the solid excrement was at once conveyed by boat. 
 Here the mass was left in open beds for several months. 
 After the liquid portion had been clarified, it was utilized for 
 the manufacture of ammonia. The remaining solid matter, 
 after drying for a time in the beds, was further dried in the 
 field, and then sold under the name of " poudrette." A 
 part of the excrement was, however, still turned into the 
 canals and found its way into the river Seine. 
 
 Still later, after it was found that the method of disposal 
 just described was not economical, the Seine became the 
 receptacle for the entire mass of this material. The condi- 
 tions which arose in consequence were so serious that a 
 commission was appointed to investigate the entire subject, 
 and, as a result, a modern filtration system was adopted. 
 
 In the meantime in Lyons, in the south of France, 
 and here and there in England, attention had already been 
 given to saving some of the human excrement for agri- 
 cultural purposes. 
 
 The history of the situation in Paris is typical in many 
 respects of the steps taken in other European cities, which 
 have finally resulted in the present methods of municipal 
 sewage disposal. 
 
 20. " Poudrette " from human excrement. — One of 
 the products sold under the name of " poudrette " is 
 prepared by the Liernur process, which consists in adding 
 to the excrement sufficient sulfuric acid to bind the am- 
 monia, after which the mass is evaporated in a vacuum 
 until it reaches such a consistency that it can be completely 
 
16 • FERTILIZERS 
 
 dried by other means and finally reduced to a powder. 
 It happened, unfortunately, that the tendency to introduce 
 foreign material, by way of adulteration, brought such 
 poudrette into more or less general ill repute. 
 
 21. Treatment of excrement with burned lime. — 
 Another but more wasteful process for the utilization 
 of human excrement consists in treating it with burned 
 lime. This method is said to have been first proposed by 
 Payen and then by A. Miiller, and upon it is based the 
 system of Mosselmann and Muller-Schiir. By this pro- 
 cess the ammonia which has been formed previously in 
 the mass is lost. It is therefore important that the excre- 
 ment be treated in as fresh a state as possible. Mossel- 
 mann used two parts by weight of burned lime to one of 
 moist excrement, and the final volume amounted to two 
 and one-half times that of the lime employed. In this 
 process 100 parts by weight of lime volatilize about 25 
 parts of water and bind chemically and mechanically 
 about 50 parts more, thus producing a product which is 
 so dry that it can be readily handled and transported, 
 and the heat generated is sufficient to destroy pathogenic 
 organisms. Such a system was in use recently in con- 
 nection with the disposal of the excrement from tenement 
 houses in certain manufacturing villages in Rhode Island, 
 and the following is the composition of the product thus 
 secured : — 
 
 Per Cent 
 
 Calcium oxid 11.28 
 
 Potassium oxid 0.09 
 
 Phosphoric acid 0.91 
 
 Nitrogen 0.43 
 
 One great objection to the material prepared by this 
 process is that it is so excessively rich in lime that if it 
 
NIGHT SOIL 17 
 
 were applied regularly in sufficient quantities to supply 
 the soil adequately with the other fertilizer ingredients, 
 it would result in liming to excess. It may, however, be 
 used frequently, for a time, on soils originally quite acid 
 or, more infrequently, on those only moderately in need of 
 liming. To meet this objection in part, basic slag meal, 
 potash salts, and other chemicals have sometimes been 
 incorporated with it before placing it on the market. 
 
 22. The " A. B. C." and other methods of conservation. 
 — In the absence of burned lime, alum, blood, and clay 
 have been added to the excrement, after which the solid 
 matter is dried, ground, and marketed under the name of 
 " native guano." This process takes its name " A. B- 
 C." from the first letter of the name of each of the materials 
 added to the excrement. A large number of other methods 
 for the disposal of human excrement, by its transformation 
 into poudrette, have been proposed from time to time. 
 Some of these, like that of Teuthorn, involve evaporation 
 and drying of the mass by natural means, whereas that 
 of Thon was based upon evaporation of the water by 
 means of artificial heat. The product as prepared by 
 Thon at Stuttgart had the following composition : — 
 
 Per Cent 
 
 Nitrogen . 4.5- 6.0 
 
 Phosphoric acid 10.0-12.0 
 
 Potash 1.5- 3.0 
 
 In connection with the many other processes which 
 have been employed for the same purpose at various 
 times, practically every conceivable absorbent and con- 
 serving material has been used. 
 
 23. The novel method of Sindermann. — Among all 
 of the methods proposed for the disposal of human excre- 
 ment, perhaps the most novel is that of A. Sindermann, 
 
18 ' FERTILIZERS 
 
 which was adopted in connection with a hotel in Breslau, 
 Germany. The excreta in this case were placed in a 
 retort, where they were not only dried, but also subjected 
 to dry distillation, in the course of which there were pro- 
 duced illuminating gas, carbon dioxid, tar, oil, and am- 
 monia. The valuable products were saved, as in the manu- 
 facture of gas from coal ; the gas, after the removal 
 of the carbon dioxid and subjection to other purification, 
 was used for illuminating purposes in the hotel. The 
 resulting ash, with a content of 5.57 per cent of water, 
 was found to contain 6.5 per cent of lime, 3 per cent of 
 magnesia, 5.5 per cent of potash, and 8.6 per cent of phos- 
 phoric acid. 
 
 24. Repeated use encourages undue leaf growth. — 
 In general, it may be said that the continued use of con- 
 siderable quantities of human excrement on land leads 
 to unusual leaf growth, and, in the case of grass land, 
 causes the lodging and consequent molding of some of the 
 crop. Its excessive use also results in delaying the fruiting 
 of other crops. The economical utilization of such mate- 
 rial depends, therefore, upon limiting the amount used to 
 that required to furnish the needed nitrogen, and on its 
 being supplemented by proper amounts of potash and 
 phosphoric acid. 
 
CHAPTER III 
 
 THE DUNG OF FARM ANIMALS AND ITS PRESERVATION 
 
 The term "farm manure " covers properly the dung of 
 all the domestic animals kept on the farm, including the 
 customary litter, night soil, peat, muck, leaf mold, other 
 vegetable refuse, and composts. Barn-yard manure, as 
 usually understood, relates to the dung of neat cattle 
 with the usual litter. Stable manure is a term at present 
 more commonly applied to the dung and litter from horse 
 stables. 
 
 25. Influence of feed and age of animal on dung. 
 
 It may be stated that in general the dung of mature 
 animals is of greater value than that of those which are 
 making rapid growth; similarly, the dung of cows not 
 with calf and especially of those not producing milk, is 
 richer than that of animals bearing their young or which 
 are yielding large volumes of milk. The reasons for this 
 are sufficiently obvious. It is assumed of course in such 
 instances that the feeds are of the same general character. 
 The dung of animals fed chiefly on grain, milk, and other 
 similar materials is richer than that of those which 
 subsist chiefly on coarse feeds, since it contains much 
 more nitrogen, the most costly of all the manurial ingre- 
 dients. 
 
 26. Influence of litter on manure. — The value of 
 dung, as it has to be dealt with in a practical way, is very 
 greatly affected by the kind and quantity of litter or 
 
 19 
 
20 FERTILIZERS 
 
 absorbents employed in the stables or yards. For ex- 
 ample, the manurial value of cacao refuse or of peat or 
 muck is of itself far greater than that of such materials 
 as sawdust, shavings, and cotton waste, which are ex- 
 ceedingly poor in nitrogen and in other less valuable 
 manurial ingredients. 
 
 27. Collecting and caring for dung. — The method of 
 collecting and of caring for the dung of the farm animals 
 may affect its value greatly. If it is thrown out under the 
 eaves of the stable, as was once a too common custom in 
 the United States, most of the liquid or more valuable 
 portion, representing about four-fifths of its total value, 
 is likely to be carried away in the rain water. If, on the 
 other hand, horse manure is allowed to lie in an undis- 
 turbed pile in a barn cellar and to undergo fermentation 
 until it reaches a " fire-f anged " condition, great loss of 
 nitrogen inevitably results. Serious, though less exten- 
 sive losses of nitrogen occur through volatilization of 
 ammonia either in the stable, cellar, or storage shed, on ac- 
 count of the failure to use chemical agents for its retention ; 
 but more particularly from leaving it either in small heaps 
 or spread upon the surface of the ground for some time 
 before the land is plowed. 
 
 28. Horse manure. — Because of the fact that the 
 horse has but one stomach, and hence does not ruminate, 
 it is not as well able as the sheep and cow to completely 
 disintegrate and digest coarse feeds. On this account, 
 and due to the presence of large amounts of fibrous 
 material, horse manure is especially open and porous in 
 character. 
 
 Subject to ready fermentation. — On account of the less 
 complete destruction of the organic compounds of the hay 
 and grain in the course of the process of digestion, horse 
 
THE DUNG OF FARM ANIMAL 8 21 
 
 manure furnishes abundant organic food for the many 
 microorganisms which promote decay, and hence it is 
 especially subject to fermentations of various kinds. This 
 fact is taken advantage of by its employment for the evolu- 
 tion of heat in greenhouses and cold-frames. Owing to 
 its loose physical character, horse manure is often mixed 
 with cow manure, for certain purposes, with distinct ad- 
 vantage to each. 
 
 The solid -portion. — The solid excrement of horses con- 
 sists chiefly of the undigested portions of the feed, as- 
 sociated with bacteria, minute quantities of biliary matter, 
 and epithelial tissue, arising from the normal destruction 
 of intestinal surfaces. The average composition of the 
 solid manure is as follows: nitrogen 0.55 percent, phos- 
 phoric acid 0.30 per cent, and potash 0.40 per cent. 
 
 The liquid portion. — The liquid excrement contains 
 soluble phosphates, potash salts, and the organic meta- 
 bolic products of the animal, such as urea, traces of crea- 
 tinin (C 4 H 7 N 3 0), and, in the case of horses at rest, small 
 quantities of hippuric acid. The urine of horses is more 
 concentrated than that of the bovine species, and it con- 
 stitutes about one-fourth of the weight of the total ex- 
 crement. The following represents the average analysis 
 of the liquid manure : nitrogen 1.35 per cent, phosphoric 
 acid a trace, potash 1.25 per cent. After being added to the 
 solid portion the mixture has the following composition : 
 nitrogen 0.7 per cent, phosphoric acid 0.25 per cent, and 
 potash 0.55 per cent. 
 
 Storage, and the use of litter. — Usually a greater percent- 
 age of litter (bedding) is used for horses than for cows, on 
 which account the manure as a whole is often of a more 
 strawy character. The value of the manure is usually 
 considered greater if straw or leaves are used for bedding 
 
22 FERTILIZERS 
 
 than if either shavings or sawdust is employed. This is, 
 however, more likely to be true if the shavings are made 
 from the wood of pine and of certain other coniferous trees. 
 Experiments are nevertheless on record, showing that cow 
 manure has been found to be equally as valuable with saw- 
 dust litter as with a litter of straw or chopped corn stalks, 
 when used for roses, carnations, chrysanthemums, and 
 sweet peas. For certain reasons, manure without litter 
 was preferred in special cases. 1 
 
 If horse manure is to be stored before its application to 
 the soil, it should be compacted at once as completely as 
 possible, and especial care should be taken to keep it moist. 
 
 Amount of manure produced per animal. — It is estimated 
 that every 100 pounds of dry matter in the feed of a horse 
 will produce about 210 pounds of manure, containing about 
 77.5 per cent of moisture. Allowing in addition 6.5 pounds 
 of bedding per day per horse, and allowing also for the 
 manure usually voided outside of the stall, there would be 
 available for use about five and one-fourth to six and one- 
 third tons of manure per horse per annum. 
 
 29. Cow manure. — The manure of neat cattle, owing 
 to their habit of ruminating and to the comparatively 
 complete digestion afforded by their four stomachs, is 
 far more compact than horse manure, and hence for many 
 purposes is improved by an admixture of the latter. 
 Nevertheless, in the preparation of soil for rose culture 
 under glass, and for certain other greenhouse, garden, and 
 farm purposes it is preferred, by many, unmixed with 
 horse manure. 
 
 Chemical composition. — The chemical composition of 
 cow manure is much like that of horse manure, though 
 
 !Pub. Int. Agr. Inst. (Rome), Ottawa Branch, Bui. 2, No. 6, July, 
 1912. 
 
THE DUNG OF FARM ANIMALS 23 
 
 it is less concentrated, and it contains about one per cent 
 of hippuric acid (C9H9NO3). 
 
 Quantity voided per cow. — The quantity of manure 
 voided by the cow is much greater than that produced 
 by the horse, which compensates in a measure for the more 
 dilute character of the liquid portion, when considering 
 the total value of the yearly product of each. The quan- 
 tity of manure excreted daily per cow, inclusive of the 
 customary quantity of absorbents, is from twenty-five to 
 thirty pounds greater than that produced by the horse. 
 One pound of dry matter in the feed will furnish about 
 3.84 pounds of manure. To this must be added the litter 
 in order to show the total amount of manure produced per 
 animal. An average cow, if properly fed, will excrete 
 approximately 65 pounds of manure per day, about 25 
 per cent of which is represented by the liquid portion. It 
 is obvious that there will be wide individual variations 
 from these figures, dependent upon the weight of the cow 
 and upon the character and digestibility of her feed. 
 
 Proportion of the nitrogen voided. — About one-fourth of 
 the nitrogen of the feed is appropriated by the cow for 
 the manufacture of her milk product, and to replace hair 
 and other waste, leaving another and less valuable fourth 
 in the solid excrement, and one-half in the liquid manure. 
 
 30. Sheep manure. — The value of the manure produced 
 by a single sheep in a year is small. The manure always 
 contains less water than that of other domestic animals, 
 the average content being about 74 per cent. Sheep 
 manure is especially prized by many florists for use in 
 greenhouses, due, doubtless, in part to its improvement of 
 the physical character of the soil ; it is also much sought 
 in some localities for application to lawns and for the pro- 
 duction of certain garden crops. Owing to the low water 
 
24 FERTILIZERS 
 
 content of sheep manure, it is liable to ferment easily and 
 to lose some of its nitrogen as ammonia. The average 
 composition of the mixed solid and liquid manure is as 
 follows : nitrogen 0.95 per cent, phosphoric acid 0.35 per 
 cent, and potash 1.00 per cent. 
 
 Amount of manure produced by sheep. — At the Cornell 
 agricultural experiment station, it was found that three 
 sheep fed for thirty-three and two-thirds days produced 
 a total of 723 pounds of solid and liquid excrement. The 
 average of a large number of German experiments shows 
 that for 100 pounds of dry matter of the feed there are 
 recovered 48.4 pounds of dry matter in the excrement. 
 In general, the multiplication of the dry matter of the feed 
 by 1.88 and the addition of the litter will give approxi- 
 mately the amount of manure. On the basis of 73 per cent 
 of water in sheep manure, 100 pounds of dry matter of the 
 feed would produce 183 pounds of manure ; or, in other 
 words, a sheep weighing about 60 pounds would consume 
 about 2 pounds of dry matter daily, which, with an amount 
 of litter such as is often used, would amount to about 1500 
 pounds of manure per year. 
 
 31. Hog manure. — As a rule, hog manure is of less 
 interest than that of other domestic animals, for the reason 
 that a large portion of it is often voided in the field. It 
 varies also so widely in composition, owing to the diversi- 
 fied character of the food consumed, that one cannot give 
 a value to it within very definite limits. Assuming the 
 food to be the same, hog manure will not vary widely from 
 the composition of the manure of other animals. The 
 average of a considerable number of experiments shows 
 that for every 100 pounds of dry matter in the feed con- 
 sumed there will be produced about 237 pounds of manure. 
 The liquid manure of hogs which have been well fed often 
 
THE DUNG OF FARM ANIMALS 25 
 
 contains as much as 2 per cent of nitrogen. The solid 
 excrement of hogs is very wet and decomposes less readily 
 than that of horses and of sheep. 
 
 A hog will void on the average from 12 to 15 pounds of 
 manure per day, which is equal to from two to three tons 
 per year. 
 
 There seems to have existed among farmers a certain 
 prejudice against the use of hog manure for certain crops, 
 although there seems to be no satisfactory experimental 
 basis at this time for definite statements on this point. 
 
 32. Hen and pigeon manure. — The manure of hens and 
 pigeons differs materially from that of the more common 
 farm animals, by reason of the fact that the excreta are 
 voided in one portion, rather than separately in solid and 
 liquid form. 
 
 Chemical composition. — A number of analyses of fresh 
 hen manure show the range in nitrogen content to be from 
 0.56 to 1.38 per cent; in phosphoric acid, from 0.35 to 
 1 per cent, with the majority ranging from about 0.47 
 to 0.92 per cent; and the range in potash is from 0.18 
 to 0.45 per cent, though the more common limits are 
 between 0.25 and 0.4 per cent. 
 
 Air-dry hen manure contains from 1.82 to 2.13 per cent 
 of nitrogen, from 0.85 to 2.21 per cent of phosphoric 
 acid, and from 0.35 to 1.11 per cent of potash. It is not 
 an ideally balanced manure for all purposes, and can usually 
 be supplemented profitably by 'the addition of a liberal 
 amount of acid phosphate and by a moderate quantity 
 of muriate of potash or of kainit. When so employed, 
 the results from its use, even in much smaller quantities 
 than otherwise, are excellent. 
 
 Both superior in their action. — The superior action of 
 pigeon and hen manure may readily be attributed in part 
 
26 FERTILIZERS 
 
 to the fact that the liquid and solid manure are voided 
 together, in consequence of which the metabolized nitro- 
 gen is less likely to suffer loss by leaching than in the case 
 of most other manures. Furthermore, it very quickly 
 undergoes nitrification after its application to the soil. 
 These manures are naturally richer in nitrogen and in 
 other fertilizer ingredients than certain coarser manures, 
 owing to the more concentrated character of the feeds 
 consumed. In view of the foregoing circumstance, these 
 manures contain less of the various organic materials 
 which characterize especially horse manure, and hence 
 furnish a smaller supply of the organic foods for the organ- 
 isms which are especially concerned in denitrification and 
 the liberation of nitrogen in a free state. 
 
 Both manures need supplementing. — The adaptability 
 of hen and pigeon manure to general trucking and garden- 
 ing purposes would often be much increased, and the 
 ammonia better conserved, if 12 to 15 pounds of acid phos- 
 phate and 18 to 20 pounds of kainit, or 4 to 5 pounds of 
 muriate of potash were added to every 100 pounds of the 
 fresh manure. It might be still further improved by add- 
 ing to each 100 pounds, 5 to 10 pounds of gypsum, or land 
 plaster. 
 
 33. Amounts of litter used as absorbents. — The quan- 
 tity of litter which should be used is not only dependent 
 upon the class of farm animals concerned, but also upon 
 the character of the food consumed ; since watery foods 
 and those containing a large amount of nitrogen cause 
 an increased flow of urine. It is generally desirable to 
 employ sufficient litter to keep the animals clean, by in- 
 suring the absorption of the liquid manure. To this end 
 it has been recommended that the amount for cattle per 
 day should be 9 pounds, for horses 6.5 pounds, and 
 
THE DUNG OF FARM ANIMALS 
 
 27 
 
 for sheep three-fifths pound. Stated in another way, the 
 litter should be equal, approximately, to one-third of the 
 dry matter consumed. 
 
 34. Comparative absorbent power of litters for water 
 and ammonia. — The ability of the litter to absorb liquid 
 may differ widely from its capacity to hold ammonia, as 
 shown in the following table : — 
 
 Kinds of Material 
 
 Water Retained 
 
 by 100 Pounds of 
 
 Material after 
 
 24 Hours 
 
 Pounds 
 
 Ammonia Absorbed 
 by 100 Pounds of 
 Different Ma- 
 terials 
 
 Pounds 
 
 Partially decomposed oak 
 leaves ....... 
 
 Peat 
 
 Needles of coniferous trees . 
 
 Spent tan 
 
 Air-dried humons soils 
 Mosses and forest leaves 
 
 220 
 
 285 
 280 
 
 162 
 200 
 600 
 175 
 435 
 450 
 50 
 275 
 
 25 
 
 0.17 
 
 i 
 
 1.10 
 0.05 
 0.66 
 0.86 
 
 1 Not determined. 
 
 It will be seen that in proportion to the amount of liquid 
 held, air-dried humous soil is a most efficient absorber of 
 ammonia. This is no doubt due in part to a chemical 
 union of the ammonia with organic acids present in the 
 humus, as well as to a similar union with zeolites and pos- 
 sibly other complex silicates of the mineral portion of the 
 
28 ' FERTILIZERS 
 
 soil. As absorbents of ammonia, peat, peat moss, and 
 humous soil take the first rank. 
 
 In so far as concerns ability to take up and hold 
 water, peat is superior to all of the other absorbents. 
 
 Both loam and peat may be used effectively in bedding, 
 as supplements to, and economizers of, straw. 
 
 In a series of tests made with cotton waste at the ex- 
 periment station of the Rhode Island State College, it was 
 found that 100 pounds of a dyed and quite clean sample 
 absorbed 435 pounds of water. The same quantity of an 
 undyed lot of similar character absorbed 550 pounds, and 
 two other lots, which contained considerable quantities 
 of fine foreign matter, absorbed but 267 and 231 pounds 
 of water, respectively. 
 
 35. The degree of conservation effected by litters. — 
 It was found by Muntz and Girard that where the loss of 
 nitrogen from the manure of cows amounted to 59 per 
 cent without the use of litter, its addition reduced the 
 losses to 50 per cent and 44 per cent. Where excessive 
 quantities of litter were employed, the losses were never- 
 theless 41 per cent. In their study of the relative effi- 
 ciency of straw and peat moss, in the preservation of horse 
 dung, it was found that the loss of nitrogen, when straw 
 was employed, was 58 per cent ; whereas with peat moss 
 it was but 44 per cent. Similar experiments with straw, 
 in the preservation of sheep manure, showed a loss of 
 50 per cent of the nitrogen, whereas by the substitution of 
 a litter of earth, the loss was reduced below 26 per cent. 
 
 36. Losses of manure lessened by packing and tram- 
 pling. — Since very early times it has been a common prac- 
 tice to pack horse manure, in order to prevent its rapid 
 fermentation and consequent " fire-fanging," which, if 
 unchecked, results in the loss of most of its nitrogen. 
 
THE DUNG OF FARM ANIMALS 29 
 
 Similar packing in the case of other manures also mini- 
 mizes the loss of nitrogen, as has been shown by numerous 
 experiments. 
 
 The compacting of horse manure and cow manure is 
 often accomplished in this country and in Europe by con- 
 fining swine or other farm animals within the inclosure 
 where the manure is stored. 
 
 In Europe it is a common practice to place the farm ani- 
 mals in deep stalls, having cemented sides and bottoms. 
 They are then littered generously and allowed to remain 
 in the stalls for several months on the accumulations of 
 manure and litter. When such methods are practiced, 
 the usual losses of nitrogen range from about 13 to 18 per 
 cent. This loss is occasioned not only through the direct 
 volatilization of ammonia, but by the transformation of 
 considerable quantities of the more readily soluble and 
 available nitrogen into less available forms, through bac- 
 terial agencies. The change of available nitrogen into 
 more inert forms also accompanies the process of denitri- 
 fication; whereby also much of the nitrogen of nitrates 
 may, under certain conditions, be liberated as gaseous 
 nitrogen. The nitrogen thus rendered inert is transformed 
 into what is commonly classified as humous nitrogen, 
 a direct product in this case of the destruction of the or- 
 ganisms of which it became at first a constituent part. 
 
 It is cited by Hall that in experiments made by Russell 
 and Goodwin, 43.83 pounds of digestible nitrogen were fed, 
 and but 3.07 pounds of it were retained by the animal 
 which consumed the feed containing it. The remainder, 
 represented by 40.76 pounds, was voided as urea. Upon 
 subsequent examination of the dung, it was found, how- 
 ever, that but 28.6 pounds of nitrogen remained in the 
 shape of ammonia and amids, and that, aside from a direct 
 
30 FERTILIZERS 
 
 loss of 7.38 pounds of nitrogen, 4.78 pounds had been 
 converted, during the fermentation, into proteins and 
 other insoluble compounds. 
 
 It has been found by Maercker and Schneidewind, in 
 experiments with steers, that manure properly trampled 
 suffers an average loss of about 15 per cent of its nitrogen, 
 but that the loss will readily rise to from 30 to 40 per cent, 
 if the manure is thrown out into piles daily, or at quite 
 frequent intervals. 
 
 The richer the manure in soluble or immediately avail- 
 able nitrogen, the greater is likely to be the percentage loss 
 of nitrogen during the making and storage, and hence such 
 manures should receive most careful attention. 
 
 37. Soil a powerful absorbent of ammonia. — In ex- 
 periments performed by Muntz and Girard it was found 
 that uncovered cow manure suffered a loss of 142 milligrams 
 of ammonia, but that, under otherwise like conditions, 
 when covered with soil to a depth of about three-quarters 
 of an inch (2 cm.) the loss was but 10 milligrams. Simi- 
 larly the loss of ammonia from uncovered sheep manure 
 amounted to 1642 milligrams, but with a covering of soil 
 like that used with the cow manure, the loss was but 128 
 milligrams. In experiments with air-dried sandy soil, 
 as a litter for sheep, the loss of nitrogen amounted to but 
 25.7 per cent of that consumed in the feed, as compared 
 with a loss of 50.2 per cent, when straw was substituted 
 for the soil. 
 
 How the soil acts in retaining ammonia. — The reten- 
 tion of ammonia by soil is probably due chiefly to three 
 causes. The first and least important is its direct absorp- 
 tion and retention by the moisture held on the surface of 
 the soil particles ; the second is its combination with or- 
 ganic acids, arising in the course of the decomposition of 
 
THE BUNG OF FARM ANIMALS 31 
 
 vegetable debris ; and the third is its entering into com- 
 bination with zeolites or similar complex silicates. In 
 this form it lends itself, nevertheless, very readily to sub- 
 sequent nitrification. It is also known that dry soil will 
 absorb gases of various kinds by condensation on the sur- 
 face of the particles, analogous to the condensation of 
 oxygen on platinum black, and of nitrogen on porous 
 copper oxid. 
 
 38. Muntz and Girard's results on the absorption of 
 ammonia. — The following data from Miintz and Girard 
 show the relative amounts of ammonia absorbed by soil 
 and other substances : — 
 
 Ammonia absorbed, per Kilogram op Dry Matter, 
 by Different Sorts of Material 
 
 Grams 
 
 Wheat straw 1.70 
 
 Pine sawdust 0.46 
 
 Mossy peat from Holland 8.63 
 
 Powdered peat 11.03 
 
 Siliceous earth 0.66 
 
 Calcareous earth 1.80 
 
 Argillaceous forest soil . 2.24 
 
 Garden soil 5.38 
 
 Peaty soil 6.60 
 
 It will be observed that the highest absorptive power is 
 possessed by peat and by soils rich in humus, whereas 
 siliceous soil and sawdust both stand low in the list. At- 
 tention has been called by Hilgard to the remarkable ab- 
 sorptive power, both for ammonia and carbon dioxid, 
 possessed by certain highly ferruginous soils of Hawaii, 
 which appear to exceed all others in this respect. These 
 soils were found to contain as much as 40 per cent of 
 ferric oxid accompanied by 3.5 per cent of humus. 
 
32 FERTILIZERS 
 
 39. The action of gypsum as a preservative of manures. 
 — Gypsum, or land plaster, has long been considered one 
 of the most important chemical substances for use in the 
 preservation of animal manures. Its value is based upon 
 its ability to transform the unstable ammonium carbonate 
 into ammonium sulfate, whereby its volatilization is 
 prevented. This reaction is expressed by the following 
 equation : — 
 
 (NH 4 ) 2 C0 3 + CaS0 4 • 2H 2 = (NH 4 ) 2 S0 4 + CaC0 3 4- 2H 2 
 
 ammonium gypsum ammonium calcium water 
 
 carbonate sulfate carbonate 
 
 It requires about 400 parts of water to dissolve 1 part 
 of gypsum, although its solubility may be somewhat 
 greater in the liquid manure. In order to be effective, 
 the manure pile must be kept quite moist in order that the 
 solution and transformation, and the consequent fixation, 
 may take place promptly and efficiently. 
 
 40. Reasons for using gypsum in excess. — In con- 
 sequence of the fact that the reverse reaction to that 
 mentioned above is possible, far more than the theoretical 
 quantity of gypsum must be used in order to insure the 
 fixation of even the chief part of the ammonia. Further- 
 more, if the mater'al loses its moisture, some of the am- 
 monia of the ammonium sulfate will be changed again into 
 ammonium carbonate. Theoretically, 10 to 12 pounds 
 of gypsum should be used per ton of dung, but in actual 
 practice from 100 to 120 pounds should be employed. 
 Another reason for the employment of more than the 
 theoretical quantity of gypsum is that potassium carbonate 
 and sodium carbonate are present in the urine, which also 
 react with gypsum in the same manner as the ammonium 
 carbonate. Still another reason for using a generous 
 
THE DUNG OF FARM ANIMALS 33 
 
 amount of gypsum is that under the most ideal conditions 
 for the storage of manure, requiring exclusion of air, con- 
 ditions are created favorable to certain anaerobic bacteria, 
 which may reduce the sulfate to sulfid. This in turn 
 readily reacts with carbonic acid to form calcium carbon- 
 ate, with simultaneous liberation of hydrogen sulfid. In 
 this way, therefore, some of the gypsum is destroyed and 
 its efficiency as a fixer of ammonia is consequently lost. 
 
 41. Gypsum safe to use. — As a manure preservative, 
 gypsum possesses the distinct advantage of being a safe 
 substance to use under the cows, in contrast to most or 
 all of the other materials ; for many of them are likely to 
 injure the feet of the cattle unless their use is restricted 
 solely to the gutters, or preferably to the manure as it 
 leaves the stable. 
 
 42. Gypsum compared with other chemical preserva- 
 tives. — It was found by Muntz and Girard, in the course 
 of their experiments, that not only gypsum, but sulfate of 
 iron, kainit, superphosphate, and calcium carbonate, had 
 but slight efficiency as preservatives of dung, a result 
 supported by the work of Julie and others. More re- 
 cently, however, Severin, in laboratory experiments with 
 unsterilized manure, as well as with sterilized manure 
 subsequently inoculated with either watery extracts of 
 manure or with pure cultures of organisms capable of 
 causing ammoniacal fermentation, found that the addi- 
 tion of 4 per cent of gypsum to the manure increased the 
 decomposition 10 to 20 per cent. It did, however, at the 
 same time effect the preservation of the ammoniacal 
 nitrogen which had been produced. 
 
 The efficiency of superphosphate as a preservative of 
 manure depends primarily upon the gypsum associated 
 with it. Its effect may be heightened in some cases by 
 
 D 
 
34 FERTILIZERS 
 
 the presence of small quantities of sulfuric acid which 
 may have been used in excess, or by the presence of small 
 amounts of free phosphoric acid. The solubility of the 
 phosphoric acid of the acid phosphate is, however, greatly 
 lessened when added to the manure, supposedly due to the 
 appropriation of the phosphorus by the microorganisms 
 present in the mass. 
 
 Further substances which have been employed at various 
 times as preservatives of manure are kieserite (crude 
 sulfate of magnesia), kainit, sulfuric acid, and moss im- 
 pregnated with dilute sulfuric acid. Sulfuric acid has 
 also been used for the preservation of liquid manure in 
 the cisterns or receptacles in which it is sometimes col- 
 lected and stored prior to its application to the land 
 The sulfates, and even sulfuric acid, are all subject to the 
 same reduction and transformation through the agency 
 of anaerobic bacteria as gypsum, on which account they 
 have sometimes proved disappointing as preservatives. 
 
 43. Preservation by antiseptics. — In order to stay or 
 prevent fermentation in manures, the use of antiseptic 
 substances has been proposed. Among these are carbon 
 disulfid and soluble fluorids, but they are too expensive 
 to justify the attempted saving in the manure. (See in 
 a later chapter a discussion of the effect of carbon disulfid 
 on soils.) An important consideration in this connection 
 is that manures, to be sufficiently effective for the growing 
 of early garden crops and for many other purposes, must 
 have undergone a certain amount of fermentation of the 
 proper kind and under proper control, before they are 
 applied to the soil. It must be obvious, therefore, that 
 the treatment of the manures with antiseptic substances 
 may in the end interfere with the fulfillment of their 
 most important function. 
 
CHAPTER IV 
 
 THE ORGANISMS AND FERMENTATION OF DUNG 
 
 It is but recently that the enormous numbers of micro- 
 organisms, and hence the great significances of varying 
 conditions upon the changes in animal excrement, have 
 been fully recognized. 
 
 44. The number of microorganisms present in cow and 
 horse manures. — When the solid excrement is voided, 
 it is already swarming with microorganisms. In one gram 
 (about one twenty-ninth of an ounce) of cow dung, which 
 had been voided but one day, Wiitrich and von Freuden- 
 reich found from 7,000,000 to 375,000,000 of organisms. 
 The number reported more recently by other investigators 
 has ranged from 7,000,000 to 90,000,000. In the dung of 
 cows kept in the stall, Guper l found from 1,000,000 to 
 120,000,000 of organisms per gram, in contrast to but from 
 1,000,000 to 4,000,000 when they were at pasture. 
 
 Better perfected methods show still greater numbers. — 
 It has also been claimed that the methods of the investi- 
 gators just mentioned were such as to give figures below, 
 rather than above, the truth, for by the later and better 
 perfected methods, W. Huttemann found in 0.1 c.c. of 
 the intestinal content of cattle 1,000,000,000,000 micro- 
 organisms. In comparisons of the feces of cattle and horses, 
 Stoklasa 2 found in a gram of the former 60,000,000 to 
 
 1 Centralb. f. Bakt., II Abt., 22 (1909), 415. 
 2 Fuhling's Landw. Ztg., 56 (1907), 411. 
 35 
 
36 FERTILIZERS 
 
 90,000,000 of microorganisms, and in the same quantity 
 of the latter, from 100,000,000 to 150,000,000. 
 
 Microorganisms in human feces. — In human feces, 
 Matzuschita 1 found as high as 18,000,000,000 per gram. 
 According to Nothnagel, the microorganisms in the feces 
 of man often constitute the chief mass of the material, 
 and J. Strasburger found that human feces contained 
 from 17 to 68 per cent of these organisms. On the dung 
 of sheep, List observed lumps consisting of many thou- 
 sands of them. Still other investigators substantiate these 
 high percentages. 
 
 45. Significance of microorganisms in manure. — It is 
 evident from what has preceded that animal excrement 
 can no longer be looked upon as a mere storehouse of plant 
 food, but as a mass teeming with the most abundant life, 
 and capable of undergoing quite different forms of de- 
 composition and of yielding widely different products, ac- 
 cording to the moisture, temperature, reaction, and the 
 kinds and amounts of undigested and metabolic residues 
 remaining therein. 
 
 46. Microorganisms in litter. — The number of micro- 
 organisms in straw litter has been found to range from 
 10,000,000 to 400,000,000 per gram. In peat, used for 
 litter, Backhaus and Cronheim have reported from 2,000,- 
 000 to 3,250,000 of microorganisms per gram. 
 
 47. Urine, when voided, essentially free from micro- 
 organisms. — The urine of healthy animals, when it is 
 voided, is either sterile or essentially germ-free. Its in- 
 fection, however, results immediately upon being voided, 
 and, being a good medium for promoting bacterial growth, 
 it is soon teeming with millions of living forms. The ad- 
 dition of the liquid to the solid excrement results in a 
 
 1 Archiv f. Hyg., 41 (1901), 210-255. 
 
ORGANISMS OF DUNG 37 
 
 rapid increase in the organisms, which give rise to the 
 formation of ammonia. 
 
 48. The numbers of bacteria decrease gradually. — 
 Mixtures consisting of litter and of solid and liquid ex- 
 crement are exceedingly rich in living organisms, although 
 their numbers finally show a decrease. In manure four- 
 teen years old, which had remained without chemical 
 treatment and which had shrunk greatly in volume, there 
 were found 12,500,000 microorganisms per gram ; whereas 
 in identical material, which had been treated with 
 kainit and the gypsum residue from the manufacture 
 of double superphosphate (" superphosphatgyps "), but 
 3,750,000 organisms were found per gram of manure. 
 
 49. The disadvantage of antiseptics. — The employ- 
 ment of distinctly antiseptic materials as additions to dung 
 would still further lessen the number of microorganisms, 
 or destroy some of them completely ; and this fact, as 
 mentioned in Section 43, has often been advanced as an 
 argument against their use as preservatives of stable 
 manure, since the value of the dung for certain purposes 
 is enhanced by properly regulated bacterial activity of 
 the right sort. To what extent and for how long this 
 would hold true for the various antiseptic substances, 
 provided the dung were reinoculated with suitable or- 
 ganisms, remains to be determined. 
 
 50. Types of microorganisms present in manure. — 
 The micrococci and streptococci are generally less numer- 
 ous in stable manure than the rod-shaped forms (true 
 bacteria) . In moist, well-composted manure, in which the 
 conditions for anaerobic fermentation are good, the in- 
 testinal streptococci are marked biochemical factors. 
 The importance of the micrococci under such conditions 
 
38 FERTILIZERS 
 
 is certainly small, and Severin 1 observed that the micro- 
 cocci in horse manure which was kept under anaerobic 
 conditions were soon destroyed. 
 
 In fresh cow dung Backhaus and Cronheim 2 found the 
 relation of liquefying to non-liquefying forms of bacteria 
 as 1 to 5.5 ; but after maintaining the material for two 
 days at 18° C, the proportion was found to be as 1 to 3.5. 
 In the fresh dung of other animals, however, the non-spore- 
 forming, short-rod forms, belonging normally and chiefly 
 to the coli-aerogenes group, were prominent. The fluo- 
 rescens and proteus forms are both frequent among the 
 liquefying groups. The brown to black fluorescens and 
 putidum types are characteristic of manure. These are 
 not only of importance in connection with the formation 
 of ammonia, but they are also active, together with other 
 closely related forms, in effecting denitrification. 
 
 51. Aerobic forms. — Aerobic, spore-forming bacteria 
 of the mycoides, subtilis, and mesentericus groups are 
 present in great numbers in both litter and solid excrement. 
 These are also of importance in the formation of ammonia. 
 Included in the foregoing groups are also some of the most 
 powerful decomposers of urea, as well as the organisms 
 responsible for the development of high temperatures in 
 loose, open manure. Among the latter may be men- 
 tioned B. subtilis, which continues active in horse manure 
 until it reaches a temperature of 71° C. In stable manure 
 at 60° to 70° C, Dupont 3 found B. mesentericus ruber, 
 but chiefly B. thermophilus grignoni. Neither attacked 
 cellulose, but both decomposed the proteins energetically. 
 The former attacked starch, sugar, and wood gum, whereas 
 
 1 Oentralb. f. Bakt., II Abt., 1 (1895), 804. 
 
 2 Ber. landw. Inst. Konigsberg, 2 (1898), 23, cited from Lohnis. 
 
 3 Ann. Agron., 27, 1902. 
 
ORGANISMS OF DUNG 39 
 
 the latter attacked sugar but slightly and starch and wood 
 gum not at all. 
 
 52. Spore-forming anaerobic forms. — The spore-form- 
 ing anaerobic bacteria may be considered as regular in- 
 habitants of the manure pile, although their presence, 
 or at least their number, is dependent to a considerable 
 extent upon the character of the food consumed by the 
 animal producing the manure. Other forms, though 
 frequently found in the liquid leachings of manure, are 
 not of special agricultural importance. 
 
 53. Actinomycetes. — The actinomycetes are also found 
 in stable manure, certain of which are capable of enduring 
 high temperatures, and others, such as the " Strahlen- 
 pilze " are of importance in connection with the forma- 
 tion and decomposition of humous substances. 
 
 54. The yeasts. — Among the yeasts the monilia species 
 and Torulacese and even the true saccharomycetes are 
 present. 
 
 55. The molds and other organisms. — The molds 
 often develop in manure to a serious extent, and at least 
 Oidium lactis passes readily through the digestive tract 
 uninjured, in which respect it differs widely from the 
 yeasts. The molds are powerful destroyers of both ni- 
 trogenous and non-nitrogenous constituents of manure. 
 This is especially true of very dry horse and sheep manure. 
 In the former their growth is the chief cause of the phe- 
 nomenon known as " fire-fanging." 
 
 Other organisms which occasionally develop upon fer- 
 mented manures, in storage, but which are of relatively 
 less agricultural importance, are the myxomycetes. 
 
 56. Animal organisms destroy bacteria. — The pro- 
 tozoa may possibly play an equally or even more important 
 part in manure than the molds and yeasts, although their 
 
40 FERTILIZERS 
 
 action is but just beginning to be understood. The recent 
 work of Russell and Hutchinson at the Rothamsted ex- 
 periment station appears to show that in the soil at least 
 amebe and perhaps certain other protozoa feed on living 
 bacteria, in some cases to such a serious extent as to greatly 
 affect the fertility of the soil. On this account such soils 
 may be improved by heating and by the application of 
 carbon disulfid, toluene, tricresol, chlorid of lime, and other 
 substances which destroy the protozoa and give the bac- 
 teria a chance to gain the ascendency. 1 
 
 The idea of the activity of microorganisms in the de- 
 composition of stable manure is not new, for special at- 
 tention was called to it by Kette in 1865. 2 
 
 57. The effect of heating and of antiseptics on manure. 
 — It was shown by Deherain that the addition of chloro- 
 form to stable manure very largely, but not completely, 
 prevented the formation of carbon dioxid, and that heat- 
 ing to a temperature of 85° C. caused the formation of 
 methane to cease. 
 
 The elder and younger Schloesing found that stable 
 manure heated at temperatures of from 70° to 80° C. 
 continued to yield small quantities of hydrogen and carbon 
 dioxid ; but less than were produced after heating to tem- 
 peratures below 70° C. 
 
 It has been shown by Severin, 3 that in completely 
 sterilized manures the formation of ammonia ceased 
 entirely, though losses of ammonia by volatilization and 
 as a result of the reaction of sulfurous acid on amids, 
 were nevertheless possible, due to chemico-physical phe- 
 nomena. 
 
 1 Science, 32 (1910), 370. 
 
 2 Die Fermentationstheorie, etc., 2d ed., p. 58 et seq. 
 
 3 Centralb. f. Bakt., II Abt., 1 (1895), 165 and 809. 
 
 
ORGANISMS OF DUNG 41 
 
 58. Destructive changes in the non-nitrogenous matter 
 of dung. — In the processes of decomposition taking place 
 in animal manures, fats and carbohydrates are destroyed 
 in large quantities. The loss of these substances is rarely, 
 if ever, less than 10 per cent, and is often in excess of 50 
 per cent. 
 
 According to Stoklasa, 1 the dry matter of stable manure 
 may contain 30 to 40 per cent of cellulose and 20 to 30 
 per cent of pentosans. In the dry matter of sheep manure 
 and straw litter the amount of pentosans has been found 
 by Duhring to be 20 and 29 per cent, respectively, and the 
 corresponding percentages of cellulose were found to be 
 21 and 38. It seems probable that there may be wide 
 variations in these percentages according to the character 
 of the food consumed, for in the air-dry dung of sheep 
 Weiser and Zaitschek. report 3.6 per cent of pentosans 
 and 3.2 per cent of starch ; in the dung of swine they 
 found under the same conditions 3.7 per cent of pentosans 
 and 3.2 per cent of starch ; and in the air-dry dung of oxen, 
 2.6 per cent of pentosans and 10.5 per cent of starch. 
 
 59. Losses not confined to the cellulose. — Certain 
 earlier investigators were inclined to the belief that the 
 chief loss of carbohydrates during the decomposition of 
 animal manures was confined to the cellulose ; yet more 
 recent investigations by Miller show that 21.7 per cent of 
 the original sugar was lost, also 18.6 per cent of the original 
 pentosans, and but 8.7 per cent of the original cellulose. 
 It was observed by Sjollema and De Ruyter de Wild, at a 
 temperature of 35° C, that under anaerobic conditions 
 the pentosans suffered heavy losses ; however, they 
 remark that this fact enhances greatly the final value of 
 the manure. 
 
 1 FUhling's Landw. Ztg., 56 (1907), 41. 
 
42 FERTILIZERS 
 
 According to Schloesing, organic matter loses more 
 carbon than oxygen, but the hydrogen content remains 
 unchanged when organic matter decomposes under ex- 
 clusion of air. 
 
 60. Most of the aerobic and anaerobic organisms in 
 dung are active. — The majority of the aerobic and 
 anaerobic organisms present in horse and cow manures, 
 have to do with the decomposition of the carbohydrates. 
 Prominent among these are the aerobacter and amylo- 
 bacter groups which give rise to volatile and non-volatile 
 fatty acids, and to extensive gas production, the latter 
 of which represents material losses of vegetable matter. 
 B. pimctatum has also been found to be a strong gas 
 producer, and B. fluorescens is a powerful liquefier of 
 starch. 
 
 61. Diastatic action. — Stable manure contains many 
 organisms which exert a diastatic action, among which 
 are the molds and the actinomycetes. Certain of the 
 bacteria belonging to the mycoides, subtilis, and mesen- 
 tericus groups act similarly at certain stages, but the 
 yeasts have no diastatic effect whatsoever. 
 
 62. The decomposition of starch. — Starch is transformed 
 by B. mesentericus ruber into carbon dioxid, formic acid, 
 and valerianic acid ; also sugar into carbon dioxid, acetic 
 acid, and butyric acid. B. suaveolens, one of the proteus 
 group, transforms starch into sugar, dextrin, alcohol, 
 aldehyd, formic acid, acetic acid, and butyric acid. The 
 action of the butyric acid bacteria upon starch has been 
 found to result in the production of small quantities of 
 ethyl alcohol, 35 per cent of butyric acid, and 9 per cent 
 of acetic acid. This action, however, depends upon 
 varying conditions, and certain members of this group 
 may even fail to attack starch at all. 
 
ORGANISMS OF DUNG 43 
 
 63. The decomposition of pectin. — Among the organ- 
 isms effecting the destruction of the pectin of straw and 
 manure may be mentioned the aerobic form B. mesen- 
 tericus ruber. The organisms chiefly responsible for the 
 destruction of pectin are, nevertheless, aided by high 
 temperatures and the exclusion of air. 
 
 64. The decomposition of cellulose. — Cellulose ap- 
 pears to be capable of destruction by anaerobi organisms, 
 denitrifying bacteria, and also by certain aerobic bacteria 
 and molds. In manure, however, owing to the lack of oxy- 
 gen and nitrates in the interior of the piles, the anaerobic 
 bacteria become the chief factors in breaking up th e cellulose. 
 
 It has been shown by the work of Omelianski and of 
 Van Senus that certain organisms which are active in the 
 formation of butyric acid (the group of B. amylobacter, 
 Van Tiegham), which were supposed to destroy cellulose, 
 do not attack it, or at least only when it is present in 
 amounts not in excess of one per cent. In the latter case 
 several of the fatty acids were formed, together with 
 traces of higher alcohols and other substances, but the 
 gases consisted of C0 2 and H, while CH 4 was entirely 
 lacking. This hydrogen fermentation, produced by B. 
 fermentationis cellulosce is therefore different from the 
 methane fermentation produced by B. methanigenes (Ome- 
 lianski), Lehm and Neum, yet both acetic acid and n-bu- 
 tyric acid are produced by the latter. Whether the methane 
 fermentation or the hydrogen fermentation shall dominate, 
 seems to depend upon the existent conditions, but usually 
 the methane fermentation is the first to develop. Both 
 sets of organisms are, however, present in the intestinal 
 tract of domestic animals and are therefore found in the 
 dung when it is voided. It appears probable from ex- 
 periments with other materials that the methane fer- 
 
44 ' FERTILIZERS 
 
 mentation may take place more readily in a neutral than 
 in an alkaline medium. In this respect the conditions 
 are quite the contrary of those favorable to the hydrogen 
 fermentation. It is probable also that in open, strongly 
 heated manure certain thermophilic decomposers of cellu- 
 lose may be present. Furthermore, the particular kind 
 and source of the cellulose may likewise be, to a certain 
 extent, a factor in determining the nature of the result- 
 ing fermentations. 
 
 65. The decomposition of fats and waxes. — In so far 
 as concerns the fats and the waxes, it appears probable 
 that at least some of them may, under certain circum- 
 stances, undergo at least a partial breaking up by an- 
 aerobic organisms. Their destruction, which takes place 
 readily in the presence of oxygen, is quickly affected 
 by exclusion of air. The glycerine which is produced as 
 a result of the process is itself quickly destroyed. This 
 destruction may be caused by B. boocopricus, an organism 
 present in cow dung, and give rise to methyl alcohol, and 
 butyric, acetic, and formic acids. 1 In any event, the 
 decomposition of the fats and waxes in the manure, when 
 it is properly stored, takes place too slowly to have any 
 great practical significance. 
 
 66. The decomposition of urea. — One of the first 
 changes taking place in stable manure is the breaking up 
 of the urea into ammonium carbonate and this finally 
 into ammonia, carbon dioxid, and water, as indicated 
 below : — 
 
 CO(NH 2 ) 2 = 2 H 2 + (NH 4 ) 2 C0 3 
 
 urea water ammonium carbonate 
 
 (NH 4 ) 2 C0 3 = 2 NH 3 + C0 2 + H 2 
 
 ammonium ammonia carbon water 
 carbonate dioxid 
 
 1 O. Emmerling, Ber. d. d. chem. Gesell., 29 (1896), 2726. 
 
ORGANISMS OF DUNG 45 
 
 This transformation of urea into ammonia is usually prac- 
 tically completed in manure piles in from four to five 
 days. 
 
 The discoverers of urea, Fourcroy and Vauquelin, 1 
 attributed the formation of ammonia to the fermentative 
 action of certain slimy substances. That bacteria play a 
 prominent part in this change was shown by the investi- 
 gations of Alexander Muller 2 and Pasteur. 3 Many later 
 investigators have studied the subject, until now the 
 number of organisms known to effect the change of urea 
 into ammonia is not only very great but also quite varied in 
 character, embracing molds and particularly members of 
 the various subdivisions of the Coccacese and Bacteriacese. 
 Among the latter are embraced the non-spore-producing 
 forms such as proteus, coli, and fluorescens, and certain 
 of the red and yellow bacteria. Among the most power- 
 ful transformers of urea are some of the spore-producing 
 bacteria, one of which, Urobacillus pasteuri Miquel, is 
 capable of transforming three grams of urea per liter in a 
 single hour. Included in the list of the more common forms 
 found in stable manure are micrococci, B. pasteuri freuden- 
 reichii; also members of the fluorescens, proteus, and coli 
 groups. Of these B. pasteuri requires nitrogen from other 
 sources than urea, though many of them are fully able to 
 depend upon urea for their nitrogen and as a source of 
 energy, provided there are also at disposal small quan- 
 tities of carbohydrates or salts of organic acids. In the 
 case of B. erythrogenes, Sohngen found that, for every 20 
 milligrams of carbon supplied in suitable form, 500 milli- 
 
 1 Annal. de Chemie, 31 (1799), 65. 
 
 2 Jour. f. prakt. Chem., 81 (1860), 469 et seq.; (1863), 217 et seq. 
 3 Comptes rend. (Paris), 50 (1860), 849-854; Ann. de chemie et de 
 
 phys., (3), 64 (1862), 50-57. 
 
46 FERTILIZERS 
 
 grams of urea were transformed into ammonia ; and in the 
 case of Urobacillus jakschii, Sohng., the relation was that 
 of 10 of carbon to 1800 of urea transformed. 
 
 There seems to be a wide diversity of opinion as to the 
 role of enzymes in the transformation of urea. 
 
 The mass of bacteria required to transform a given 
 quantity of urea is surprisingly small, since Miquel has 
 shown that one part by weight of a culture of Urobacillus 
 duclauxii was capable of changing 4000 parts of urea into 
 ammonia, and Burchard, in experiments with Microc. 
 ureoB liquefaciens, found it capable of transforming urea 
 into ammonia to the extent of from 180 to 1200 times its 
 own weight. Not only is the change rapid, and also great, 
 in proportion to the mass of organisms acting, but it is 
 likewise often practically absolute. 
 
 67. The decomposition of hippuric acid. — As com- 
 pared with urea, hippuric acid is decomposed with much 
 difficulty, the resulting products being glycocoll and ben- 
 zoic acid, according to the following chemical equation : — 
 
 C 6 H 5 CO • NH • CH 2 COOH + H 2 = 
 
 hippuric acid water 
 
 CH 2 (NH 2 )COOH + C 6 H 5 -COOH 
 
 glycocoll benzoic acid 
 
 The same organisms which actively promote this trans- 
 formation also promote the formation of ammonia from 
 the glycocoll. ' 
 
 Many of the organisms which produce ammonia from 
 urea have the same action upon hippuric acid. Never- 
 theless, certain organisms which decompose the one do not 
 appear to act strongly on the other. There are, in fact, 
 certain specific decomposers of urea, hippuric acid, and of 
 uric acid. 
 
ORGANISMS OF DUNG 47 
 
 68. Changes produced in uric acid. — Under the in- 
 fluence of B. arce and of B. fluorescens liquefaciens, both 
 urea and ammonia are produced. 1 
 
 It was found by Giglioli that in a case of spontaneous 
 infection of a solution of uric acid, only urea and carbon 
 dioxid were formed, though Schellmann encountered 
 under similar circumstances organisms capable of decom- 
 posing both uric acid and urea. 
 
 By the action of Penicillium glaucum uric acid is 
 transformed into ammonia, although Aspergillus amidase 
 has no effect upon it. Without attempting to go into the 
 details of the subject, it suffices to state that uric acid 
 very readily yields ammonia under the conditions of fer- 
 mentation usually existent in dung heaps. 
 
 69. Ammonification of solid manure and litter. — 
 Under the conditions accompanying the usual normal 
 fermentation of stable manure, the quantity of ammonia 
 actually produced from the nitrogenous substances of 
 the solid excrement and of the litter is very small. It 
 has been shown repeatedly that a condition most favora- 
 ble to the formation of ammonia from such substances is 
 exclusion of air. In an experiment by Jentys 2 only one 
 •per cent of the nitrogen of solid excrement was changed 
 into ammonia in the course of one month under free access 
 of air, but, in an artificial atmosphere of nitrogen, 11 per 
 cent of nitrogen was changed into ammonia in the same 
 period of time. In experiments with a mixture of ma- 
 nure and straw, Dietzell 3 found that but 3 per cent of the 
 nitrogen was changed into ammonia at the end of six 
 
 1 F. and L. Sestini, Landw. Vers-Sta., 38 (1890), 157-164. 
 
 2 Anzeiger d. Akad. d Wissench., Krakau (1892), 194; cited from 
 Lohnis. 
 
 8 Landw. Vers-Sta., 48 (1897), 163 et seq. 
 
48 FERTILIZERS 
 
 months, in case care was taken to secure good aeration ; 
 but that under exclusion of air about 20 per cent of the 
 nitrogen had been changed into ammonia. The conditions 
 therefore best suited to the formation of ammonia from 
 urea are, according to the authorities just mentioned, 
 quite the opposite of those essential to the production of 
 ammonia from the solid excrement. On this point, how- 
 ever, Deherain and Dupont l disagree with the other in- 
 vestigators, for they hold that under anaerobic conditions 
 the transformation of the albuminoid substances of the 
 solid excrement and of the litter into ammonia is very- 
 slight, and that it takes place far more readily in the pres- 
 ence of air. 
 
 The reasons for the slowness of the formation of am- 
 monia in the solid excrement are made perhaps more 
 appreciable when one recalls that it is composed, to the 
 extent of one-half of its nitrogen content, of the materials 
 which have already resisted the action of the digestive fer- 
 ments of the stomach or stomachs and of the intestines ; 
 and that approximately the other half of the nitrogen is 
 in the bacteria and other lower organisms voided with 
 the manure. The importance of this point is further 
 emphasized by the fact that the organisms mentioned are 
 rich in nuclein compounds, and in chitin, all of which 
 are highly resistant to decomposition. Furthermore, the 
 antienzymes present in the living organisms afford a 
 certain resistance to their decomposition and destruction, 
 even for a considerable time after their life-functions have 
 ceased. 
 
 70. Terms used in discussing the decomposition of 
 dung. — Most of the earlier writers have attempted to 
 
 « Ann. Agron., 27 (1901), 401-427; Abs., Zentralb. f. Agr. Chem., 81, 
 240. 
 
ORGANISMS OF DUNG 49 
 
 classiiy the different stages or conditions of the decomposi- 
 tion ot animal manures, as fermentation, eremacausis, 
 molding, or putrefaction, but no definite lines of demarca- 
 tion of these processes, resting upon a scientific basis, has 
 been found possible. It is, however, quite customary 
 to consider the last two processes as taking place under 
 exclusion of air, and by many the last is held to relate 
 chiefly to the changes in animal matter, though certain 
 writers apply it equally to the changes in the vegetable 
 proteins. For the promotion of eremacausis, on the con- 
 trary, free access of air is an absolute necessity. The 
 production of ammonia was considered by W. Eber : 
 as a sure indication of putrefaction, whereas others have 
 considered that the formation of skatol, indol, ammonia, 
 hydrogen sulfid, or aromatic substances gave such indi- 
 cations. Some writers, in agreement with Pasteur, 2 con- 
 sider the term applicable only to the decomposition of 
 the protein bodies under anaerobic conditions and as 
 inapplicable to their decomposition when caused by cer- 
 tain aerobic organisms (proteus forms). It has been 
 proposed by Hiller 3 that, in place of the previous indefinite 
 terms, there should be substituted hydration, reduction, 
 and oxidation. It has been pointed out also that it 
 depends upon the existing conditions whether the changes 
 that take place in a given lot of manure shall receive the 
 one or the other designation. As these changes cannot 
 be based on definite chemical or biochemical processes, 
 owing to the variations in the character of the materials 
 at different times and in different parts of a pile of 
 manure, there seems to be little gained in attempting 
 
 1 Zeits. f. Fleisch und Milchhyg., / (1891), 118. 
 
 2 Comptes rend. (Paris), 56 (1863), 1189-1194. 
 
 3 Die lehre von der Faulniss (1879), 18-33 and 47. 
 £ 
 
50 FERTILIZERS 
 
 to give to these terms more than their original very 
 general significance. One should, therefore, by all means 
 avoid their use wherever definite scientific terms can be 
 employed. 
 
 71. The nature and cause of the losses occurring in 
 manure. — It should be borne in mind that the change of 
 urea into ammonia is the result of two stages of transforma- 
 tion ; first, to ammonium carbonate, and then to ammonia 
 and carbon dioxid. If the reaction could be stopped at 
 the end of the first stage by maintaining plenty of mois- 
 ture and an excess of carbon dioxid, and if the exclusion 
 of the air could also be accomplished, the second stage 
 would not readily follow. Under the usual conditions, 
 however, not only in urine itself, but also in the usual dung 
 heap, the free movement of the air causes the removal 
 of the excess of carbon dioxid, thus creating conditions 
 favorable to the dissociation of a part of the ammonium 
 carbonate. In addition to the direct volatilization of 
 ammonia due to the previous loss of carbon dioxid, am- 
 monia is also subject to direct oxidation into nitrogen gas 
 and water. This change is readily effected by bacterial 
 action when the manure pile is open and loose, so that the 
 air gains free access. Even though the production of 
 carbon dioxid takes place abundantly under such condi- 
 tions, it is naturally dissipated into the air, thus rendering 
 little aid in preventing the dissociation of the ammonium 
 carbonate and the consequent loss of ammonia. 
 
 72. Losses less by fermentation when moist and com- 
 pact. — In cases where the manure is kept very moist 
 and well trampled from the outset, the aerobic processes 
 just described are replaced, after the consumption of the 
 small volume of oxygen in the mass, by those of an anaero- 
 bic character, giving rise to abundant hydrogen and carbon 
 
ORGANISMS OF LUNG 51 
 
 dioxid, under conditions which preclude the ready escape 
 of ammonia. Following the period of the more rapid 
 evolution of hydrogen (which is determined by the con- 
 tinued presence of oxygen and the time required to effect 
 the destruction of the more readily decomposable carbo- 
 hydrates), the evolution of methane increases greatly, 
 accompanied also by evolution of carbon dioxid, the for- 
 mation of water, and the destruction of much of the cellu- 
 lose. The rise of the temperature of the pile, due to the 
 changes induced by the utilization of the oxygen by the 
 aerobic bacteria present in the mass, is soon followed by a 
 material drop in the temperature. 
 
 73. Losses increased by bacteria from intestinal tract. 
 
 — Aside from the changes which have been mentioned, 
 still others initiated by bacteria from the intestinal tract 
 (among which is B. coli communis), aided by micro- 
 organisms present in the air, bring about the destruction 
 of the proteins and effect their transformation into amids, 
 amino-acids, and eventually ammonia. These changes 
 are accompanied by the formation of various fatty acids, 
 chief among which is butyric acid. 
 
 74. Losses smaller in the later stages of decomposition. 
 
 — It is a notable fact that in the later stages of the fer- 
 mentation of stable manure, only small direct losses of 
 ammonia take place. This is readily understood, in view 
 of the enormous numbers of bacteria and other organisms 
 involved in the many transformations taking place in the 
 nitrogenous and non-nitrogenous portions of the litter 
 and manure ; for considerable quantities of the ammonia 
 are built up into the structure of the organisms themselves, 
 whereby it becomes less subject to material loss, though 
 depreciating greatly its immediate manurial efficiency. 
 In other words, the ammonia becomes transformed, by 
 
52 FERTILIZERS 
 
 this process, into combinations similar to those existing 
 in the soil humus. 
 
 As a result not only of the fermentation of the carbohy- 
 drates, but also of the proteins of the dung and litter, 
 organic acids are formed, which are neutralized by the 
 ammonia. Carbonates of the alkalies are likewise pro- 
 duced in the course of the destructive processes, and these, 
 by their solvent action upon the dead bacteria, give rise 
 to the dark liquors which are characteristic of the leachings 
 of old dung heaps. 
 
 Least when only the ammoniacal stage has been reached. — 
 The best results are to be expected from manure which 
 has passed only to the second or ammoniacal stage, rather 
 than from that which has reached the most advanced stage 
 of decomposition, for the ammonia is then ready to undergo 
 immediate nitrification as soon as the manure is brought 
 into the soil. Furthermore, at this stage the vegetable 
 matter is so far destroyed as not to have a serious effect 
 upon plants or to greatly promote the destruction of ni- 
 trates in the soil. At the same time, also, there is much 
 material still present in forms suitable for promoting the 
 growth of such organisms as assimilate nitrogen directly 
 from the air, which, in their turn, add to the store of nitro- 
 gen in the soil. 
 
 75. Fresh manure lacks immediate effectiveness. — 
 The idea has been handed down from early in the last cen- 
 tury that fresh stable manure can be employed with the 
 best results only when considerable time elapses between 
 its application and the date of planting. The effect of 
 fresh manure is said to be worse in light soils than in 
 those which are heavy. Many writers insist that the straw 
 in the litter should be quite well broken up by the processes 
 of decomposition before its application. The time nee- 
 
ORGANISMS OF DUNG 53 
 
 essary for the accomplishment of this varies greatly with 
 the location and the season. It would naturally take place 
 more quickly in a moist, warm climate than in one which 
 is dry and cold. In the winter these desired changes may 
 require a period ranging from eight to twenty weeks. 
 
 76. The great necessity of moisture in heaps of solid 
 manure. — From what has preceded, it appears that the 
 best condition for the preservation of solid manure is that 
 it should be kept moist by the liquid excrement, or, if this 
 is insufficient, by additions of water. This is well recog- 
 nized in France and other European countries where the 
 manure is kept under cover, and is so situated that any 
 seepage from it may be pumped back again upon the top 
 of the pile. If in such cases a considerable loss of liquid 
 results by evaporation, water is added to replace it. For 
 a similar reason it is a more or less common practice among 
 gardeners who buy large quantities of stable manure, to 
 be stored in piles in the field, to have the tops of the piles 
 incline towards the center so that they w r ill catch rather 
 than shed the rainfall. This prevents too rapid changes 
 and the losses due to the presence of oxygen and the con- 
 sequent rapid multiplication of undesirable classes of 
 microorganisms. 
 
 77. The preservation of the liquid manure. — It is 
 important in the preservation of the liquid manure that it 
 be subjected to both the chemical and physical absorbent 
 action of the litter. If the liquid manure is collected in a 
 cistern or reservoir by itself, the receptacle should be 
 closed tightly in order to prevent the passage of air cur- 
 rents over it, for the ideal condition for the preservation 
 of liquid manure is to have it covered with a layer of carbon 
 dioxid gas which prevents the rapid dissociation of the 
 ammonium carbonate. It is probably safe to assert that 
 
54 FERTILIZERS 
 
 even if the greatest care is taken to preserve the liquid 
 manure as completely as possible by itself, there is never- 
 theless more loss than if it is mixed with the solid manure 
 and is then spread on the soil at once or at frequent 
 intervals. 
 
CHAPTER V 
 
 THE PRACTICAL UTILIZATION OF MANURES 
 
 The important feature in connection with manures is 
 that what has been learned in relation to their fermentation 
 and conservation be applied in a practical way, and these 
 matters will now be discussed in detail. 
 
 78. Storage versus direct application of manure. — 
 It is still a much discussed subject whether stable manure 
 should be allowed to lie in the stable or under a shed until 
 needed, or whether it should be hauled to the field and 
 spread as rapidly as it is produced. At all events, if the 
 choice lies between its remaining for several days or weeks 
 in a loose heap before it can be spread, especially in the 
 summer time, or its being trampled down and preserved 
 at once, together with the liquid manure, no doubt the 
 latter is by far the better method of storage. If, however, 
 the manure can be hauled out daily and incorporated with 
 the soil at once, the greatest possible conservation of the 
 nitrogen will result. If the manure is spread broadcast 
 in the field just prior to a rain, the soluble portion will be 
 carried into the soil, and the loss of nitrogen will then be 
 reduced nearly to a minimum. 
 
 The danger of the loss of manure on ordinary slopes, 
 under usual conditions, by surface leaching, is not great 
 unless the soil is exceptionally impervious and the rainfall 
 unusually heavy and long continued . Applications should , 
 however, never be made on such locations when the land 
 is frozen deeply or when it is covered with a thick bed of ice. 
 
 55 
 
56 FERTILIZERS 
 
 When the ground is fairly level and is not frozen mate- 
 rially, even if covered with light or moderate amounts of 
 snow, the dung of horses and cattle can be applied with 
 much safety. 
 
 There is much to be said from a practical business 
 standpoint in favor of the direct application of such 
 manures to the land, even aside from the prevention of 
 manurial losses. If they are not applied as produced, the 
 farmer finds himself seriously handicapped in the spring by 
 the necessity of hauling them out when the planting should 
 be in progress, and thus a series of delays and consequent 
 losses often follow throughout the year. 
 
 79. Immediate incorporation of manure with the soil. 
 — From the standpoint of the conservation of the am- 
 monia, probably no more rational advice could be given 
 than that by Deherain, to the effect that a shallow furrow 
 should be turned over the manure, if possible, as rapidly 
 as it is applied to the land. In view, however, of the great 
 cost of labor in the United States, a second plowing of the 
 land, such as would be required by this method, would 
 hardly make it an economical proposition. On light soils, 
 it would be more advisable to turn the manure under in 
 one operation, to the usual depth of plowing, and on heavy 
 soils to spread it after plowing and then incorporate it 
 with the soil by immediate harrowing. 
 
 80. Losses occurring in heaps in the field and if broad- 
 casted. — If well fermented manure must be hauled to the 
 field a considerable time before it can be incorporated with 
 the soil, either by plowing or harrowing, the ammonia 
 will be best conserved if it is placed in large piles. In case 
 it is left in small heaps, as was formerly the common prac- 
 tice in New England, until it is convenient to spread it, 
 the sun dries out the liquid, the winds carry away the car- 
 
THE PRACTICAL UTILIZATION OF MANURES 57 
 
 bon dioxid, the dissociation of the ammonium carbonate 
 is thus facilitated, and the ammonia is rapidly volatilized. 
 One of the most serious wastes which can occur is from 
 leaving such manure spread for a long time upon the surface 
 of the ground in pleasant weather, exposed to the sun and 
 wind. Under such conditions, great losses of ammonia 
 are inevitable. As compared with the losses which may 
 result in this manner, those due to the usual application 
 of fresh manure directly to the soil are probably very small. 
 
 81. The time to spread manure on fields. — If on any 
 account partially fermented manure must be allowed to lie 
 on the surface of fields for some time before it can be in- 
 corporated with the soil, its application should preferably 
 take place just prior to or during a fall of rain, or upon a 
 light, fresh fall of snow, in order that the ammonium 
 carbonate may be carried directly into the soil, for, as 
 explained previously, the soil readily absorbs and holds 
 ammonia, excepting under conditions not commonly met 
 with in agricultural practice. 
 
 82. Certain vegetable substances aid denilrification in 
 manures. — The scientific study of the management of 
 animal manures was taken up a few years ago with re- 
 newed interest as a result of inducements offered by the 
 Deutsche Landwirtschafts Gesellschaft (German Agricul- 
 tural Society). In the course of this work it was found by 
 several German investigators that the solid excrement of 
 certain farm animals was worse than useless, for, by its 
 incorporation with the soil, crops were lessened rather than 
 increased. This led to a study of the action of straw in 
 order to learn if it, or solely the solid excrement with which 
 it was commonly associated, was responsible for this 
 effect. As a result, it was found that straw also, when 
 incorporated with the soil, often lessened rather than in- 
 
58 FERTILIZERS 
 
 creased the yields. The further pursuit of the problem 
 led to the discovery that the ill effects resulting from the 
 employment of the straw and the fresh excrement of farm 
 animals, in large quantities, were caused chiefly by the 
 destruction of the nitrates within the soil, whereby a large 
 portion of their nitrogen was liberated from the soil as 
 free nitrogen gas, and in consequence the plants suffered 
 from nitrogen hunger. It was also believed for a time that 
 this ill effect of straw was because of its being a possible 
 carrier of the denitrifying organisms and that its malign 
 influence was directly attributable thereto. 
 
 83. Losses by denitrification less serious if used moder- 
 ately. — As a protest against the foregoing results and 
 against the conclusions drawn therefrom, attention should 
 be called to the common experience of farmers and also 
 to the long-continued experiments with animal manures 
 at Rothamsted, England, from which their immediate, as 
 well as their long-enduring, effects are evident. Further- 
 more, at Rothamsted the yields were greatly increased by 
 supplementing the barn-yard manure with nitrates, from 
 which it is evident that the latter were probably not 
 wholly destroyed. In this connection much credit is due 
 to Deherain for pointing out the fact that in many of the 
 German experiments, which were mostly conducted in 
 pots, boxes, or small soil receptacles of various kinds, the 
 ratio of the manure and straw to the soil was far greater 
 than is customary in actual field practice, where, except- 
 ing in truck farming, only from four to ten cords of manure 
 per acre are usually employed. It was also pointed out 
 by Deherain that with all of the other conditions uniform, 
 starch and other carbohydrates, including the pentosans, 
 became the determining factors in causing the destruction 
 of nitrates. In fact, it was shown conclusively that by the 
 
THE PRACTICAL UTILIZATION OF MANURES 59 
 
 use of unduly large amounts of straw and of solid manure, 
 the soil became well supplied with the carbohydrate foods 
 required by the denitrifying organisms, whereby their 
 multiplication in the soil and their activity as destroyers 
 of nitrates were greatly increased. 
 
 From what has preceded it appears that the greatest econ- 
 omy in the use of coarse animal manures in the field is prob- 
 ably effected by the use of small or moderate applications, 
 rather than by large ones. These observations also show 
 another reason why partially rotted manure is much su- 
 perior, for inducing quick growth, to comparatively fresh 
 manure ; for the former is much more heavily charged with 
 food for the denitrifying organisms than that which has 
 undergone a greater amount of fermentation. 
 
 84. Other factors affecting losses by denitrification. — 
 It is obvious, also, that the manure of animals which have 
 digested their food the most thoroughly is less likely to 
 induce denitrification than that which is less completely 
 acted upon by the digestive agents. The effect of manure 
 in inducing denitrification is obviously determined, to some 
 extent, by the character of the food consumed. 
 
 It has been shown experimentally that if a given amount 
 of vegetable matter is introduced into the soil in a coarse 
 condition and in a manner which does not admit of a com- 
 plete admixture with the soil, it is less serious by way of 
 inducing the destruction of nitrates than when the same 
 material is ground and carefully mixed with the entire 
 mass of the soil. The explanation is that in the latter 
 case food is present at every point in the soil for the denitri- 
 fying organisms, which insures their general distribution 
 and consequent greater destruction of nitrates than would 
 be possible if they were only distributed here and there 
 wherever the coarse portions of vegetable matter happened 
 
60 ' FERTILIZERS 
 
 to be present. Herein is found a partial explanation of 
 the alleged better results secured on certain soils by plow- 
 ing under the manure than by harrowing it into the soil 
 in a thorough manner. 
 
 85. The lasting effect of stable manure. — Notwith- 
 standing all that has been said about the immediate action 
 of large quantities of litter and of solid manure by way of 
 favoring denitrification, their beneficial after effects in the 
 soil are of long duration, as the Rothamsted experiments 
 have fully demonstrated. In this connection Director 
 Hall of the Rothamsted station gives the results on grass 
 where stable manure was applied at the rate of 14 tons per 
 acre per annum for eight successive years (1856-1863), 
 the land then being left in grass without manure or fer- 
 tilizer for forty years. These results are compared with 
 those secured on a similar field to which no manure was 
 applied. The greatest increase over the unmanured area 
 was in 1865, two years after the last application was made. 
 The gain in that year amounted to 120 per cent. In the 
 decade from 1866 to 1875, and for the three decades there- 
 after, the average increase in the produce, due to previous 
 applications of manure, was 57, 24, 6, and 15 per cent, re- 
 spectively. 
 
 In connection with the Rothamsted barley experiments, 
 one plat received 14 tons per acre of stable manure for 
 each of the twenty years from 1852 to 1871 ; a second plat 
 has received the same amount per annum continuously; 
 and a third has had none. The results show that the 
 yields are still more than twice as great on the plat which 
 received the manure for the twenty years as where none 
 hag been applied. The yields are now, nevertheless, only 
 about 40 per cent of what they are where the application 
 of manure has been continuous. Attention is called, 
 
THE PRACTICAL UTILIZATION OF MANURES 61 
 
 however, by Hall to the fact that such a long duration of 
 the effect of residues of farm-yard manure would not be 
 perceptible in ordinary farm practice, and that they only 
 become apparent when the soils are cropped to a state 
 of exhaustion which is most unusual. 
 
 86. Manure profitably supplemented by chemical 
 fertilizers. — Where farm-yard manure commands a high 
 price, or where the cost of hauling is great, it is usually 
 better economy to employ only moderate amounts and to 
 supplement it with chemicals, than to place entire de- 
 pendence upon it. This is well shown by experiments 
 at Rothamsted in which the use of 200 pounds of nitro- 
 gen in stable manure resulted in a yield of but 27.2 tons 
 of mangel wurzels, as compared with a yield of 33 tons 
 where but 86 pounds of nitrogen were applied in nitrate 
 of soda, which was properly supplemented with potash 
 and phosphoric acid. The farm-yard manure used with 
 the same amount of nitrate of soda gave a yield of 41.4 
 tons, and when further supplemented by potash and phos- 
 phoric acid, the yield was only increased about 0.1 ton. 
 Had the precaution not been taken to add potash salts 
 with the manure and nitrate of soda, there would have 
 been reason for concluding that the differences in yields 
 were possibly attributable to the soda of the nitrate of 
 soda, rather than to the nitrogen. This is evident from 
 the experiments conducted at the Rhode Island station, 
 in which it was found that the yield of mangel wurzels 
 could be doubled by the employment of either sodium 
 carbonate or sodium chlorid, even when as much as 330 
 pounds per acre of muriate of potash, or its equivalent 
 of potassium carbonate, had already been used in the 
 manures. In this case, however, it was found to have 
 been probably due not alone to possible liberation of pot- 
 
62 FERTILIZERS 
 
 ash from the soil, but to direct substitution of the soda, for 
 at least a part of the potash, in connection with the require- 
 ments for bases, or in one or more of the physiological 
 functions of the plants. 
 
 87. Factors governing use of manure and chemicals. — 
 If, in the operations of the farm, the products can be fed 
 at a good profit, so that the farm-yard manure can be 
 secured as a costless by-product in sufficient quantities to 
 meet the entire manurial needs of the farm, it should be 
 used as generally as possible even for the top-dressing of 
 grass land. It may even be used in connection with the 
 potato crop, under favorable conditions, provided the 
 " seed " tubers are properly treated with formalin or 
 corrosive sublimate solution for the prevention of scab. 
 
 If the supply of manure is small, the potato crop is one 
 for which chemical fertilizers can usually be substituted 
 to good advantage, particularly as the fertilizers are more 
 likely to produce a crop free from scab and from insect 
 injury. 
 
 88. The use of coarse manures. — If the manure is 
 coarse, by virtue of being mixed with bulky litter, it is 
 poorly adapted to the top-dressing of grass land. For such 
 purposes the employment of fresh manure during the late 
 autumn and in the winter months may be permissible, 
 if there is no better use for it elsewhere. For spring top- 
 dressing the manure should by all means be fine, and, if 
 applied at such times as to avoid excessive losses of am- 
 monia, it may be well rotted. The application of coarse 
 manure may not only smother the grass, but there is also 
 danger that some of the material will finally be raked up 
 with the hay. On account of the fact that the soluble 
 ingredients of manures diffuse but little laterally in the 
 soil, it is important that top-dressings be very evenly 
 
THE PRACTICAL UTILIZATION OF MANURE 63 
 
 distributed, but this is difficult of accomplishment if the 
 manure is excessively coarse. 
 
 If the manure is coarse and it is used on light soils, it 
 may be plowed under, but if it is fine and it is to be applied 
 to rather heavy soils, it is usually considered preferable to 
 harrow it into the soil. As a general rule, farm-yard 
 manure should be applied to hoed crops. 
 
 89. Reason for even spreading of manure. — The 
 failure of fertilizers and manures to move laterally in the 
 soil has been abundantly observed at Rothamsted, and it 
 may be readily seen where a soluble chemical fertilizer is 
 applied to grass land, for even after abundant rains the 
 effect is often hardly visible for more than an inch or two 
 beyond the limit to which it has been spread. 
 
 90. Manure favors the disintegration of old soil. — 
 In breaking up old grass fields, the soil of which is in poor 
 tilth, it is advisable to spread a small amount of stable 
 manure broadcast before plowing, since it will serve as an 
 efficient aid in hastening the decomposition of the turf, 
 which is one of the first and most important steps in the 
 line of effective soil improvement. This may be followed, 
 if required, by an application of lime, which should be 
 most thoroughly harrowed into the soil. Support for 
 this proposed method of using stable manure is afforded 
 by the recent experiments of A. Koch, 1 who inoculated 
 mixtures of soil and cellulose, with ordinary soil, compost, 
 barn-yard manure, and sewer slime. The average amount 
 of cellulose consumed in six months amounted to 1.2 
 grams when soil was employed, to 3.85 grams with com- 
 post, to 10.35 grams with farm-yard manure, and to 1.85 
 grams with sewer slime. The average amount of nitrogen 
 finally present in each, in milligrams per 100 grams of 
 
 1 Abs. E.S.R. 27 (1910), 429. 
 
64 ' FERTILIZERS 
 
 dry soil, was 10.73 with soil, 92.05 with compost, 117.27 
 with stable manure, and 87.15 with sewer slime. From 
 this it will be seen that the organisms present in the stable 
 manure rendered possible the use of the cellulose as a 
 source of energy in connection with the fixation of atmos- 
 pheric nitrogen. Thus the introduction of stable manure 
 into the soil, even in small quantities, may not only aid 
 the decomposition of the excess of grass roots, whereby 
 the general tilth is improved, but it may also aid materi- 
 ally by encouraging the growth of those organisms which 
 assimilate atmospheric nitrogen, quite independent of the 
 growth of legumes. 
 
CHAPTER VI 
 
 SEA-WEEDS 
 
 Under the name of sea-weeds are sometimes grouped not 
 only the marine algse, but occasionally other marine plants, 
 one of the most 
 common of 
 which, on cer- 
 tain coasts, is 
 the eel-grass, 
 or grass-wrack 
 (Zostera ma- 
 rina), which be- 
 longs to the 
 Naidacse or 
 Pond- we e d 
 family. 
 
 The number 
 of marine 
 plants which 
 are not algae is 
 very small on 
 the New Eng- 
 land coast, and 
 is said to hardly 
 exceed half a 
 dozen. 
 
 91. The value of sea-weed known to the ancients. — 
 The use of sea-weed as a manure was already well known to 
 f 65 
 
 Fig. 2. — Sea-weed for Fertilizing. 
 Ribbon-weed, kelp, tangle {Lamina ria saccharina). 
 
66 
 
 FERTILIZERS 
 
 the early Romans, as is shown by the writings of Palla- 
 dium, who stated that after washing with fresh water, it, 
 with other substances, can take the place of manure. 
 Sea-weed has long been used for manurial purposes in the 
 islands of Thanet and Jersey ; also in the Hebrides, Scot- 
 land, England, Ireland, Wales, Sweden, and elsewhere. 
 
 Percentage Composition of Sea-weeds 1 
 
 
 
 
 Phos- 
 
 
 
 
 
 Water 
 
 Nitro- 
 
 phoric 
 
 Pot- 
 
 Lime 
 
 Mag- 
 
 
 
 gen 
 
 Acid 
 
 ash 
 
 
 nesia 
 
 Ribbon-weed, kelp, or tan- 
 
 
 
 
 
 
 
 gle {Laminaria saccha- 
 
 
 
 
 
 
 
 
 SS.O 
 
 0.17 
 
 0.05 
 
 0.16 
 
 0.38 
 
 0.17 
 
 Broad ribbon-weed, broad- 
 
 
 
 
 
 
 
 leafed kelp, devil's 
 
 
 
 
 
 
 
 apron, or tangle (Lami- 
 
 
 
 
 
 
 
 naria digitata) 2 
 
 87.5 
 
 0.23 
 
 0.06 
 
 0.31 
 
 0.41 
 
 0.22 
 
 Dulse, or dillisk (Rhody- 
 
 
 
 
 
 
 
 menia palmata) 2 . . . 
 
 86.3 
 
 0.37 
 
 0.09 
 
 1.07 
 
 0.46 
 
 0.09 
 
 Round-stalked rock-weed 
 
 
 
 
 
 
 
 (Ascophyllum (Fucus) 
 
 
 
 
 
 
 
 
 77.3 
 
 0.24 
 
 0.08 
 
 0.64 
 
 0.48 
 
 0.35 
 
 Flat-stalked rock-weed 
 
 
 
 
 
 
 
 (Fucus vesiculosus) 2 . 
 
 76.6 
 
 0.38 
 
 0.12 
 
 0.65 
 
 0.45 
 
 0.31 
 
 Phyllophora membranifolia 2 
 
 66.2 
 
 1.0S 
 
 0.14 
 
 0.96 
 
 5.11 « 
 
 0.69 
 
 Irish, or Carrageen, moss 
 
 
 
 
 
 
 
 (Chondrus crispus) 2 . 
 
 76.0 
 
 0.57 
 
 0.13 
 
 1.02 
 
 0.49 
 
 0.33 
 
 Cladoslephus verlicillatus 3 . 
 
 71.2 
 
 0.45 
 
 0.22 
 
 1.42 
 
 0.87 
 
 0.36 
 
 Polyides rotundus 3 . . . 
 
 58.5 
 
 0.70 
 
 0.16 
 
 1.45 
 
 0.37 
 
 0.46 
 
 Ahnfeldtia plicata 3 . . . 
 
 59.0 
 
 1.35 
 
 0.25 
 
 0.59 
 
 0.98 
 
 0.29 
 
 Eel-grass, or grass-wrack 
 
 
 
 
 
 
 
 (Zostera marina) 2 
 
 81.2 
 
 0.35 
 
 0.07 
 
 0.32 
 
 0.51 
 
 0.32 
 
 1 A tabulation of analyses of sea-weeds by a number of analysts, in 
 several different countries, all of which are reduced to a dry basis, may 
 be found in Bulletin No. 21, Rhode Island agricultural experiment 
 station, pp. 34-36. 
 
 2 Average of samples taken in January, March, and September. 
 ' 3 Samples taken in September. 
 
 4 More or less small shells adhered to the plants, which explains the 
 exceptionally high lime content. 
 
SEA-WEEDS 
 
 C7 
 
 92. Chemical composition of sea-weeds. — Most of 
 the earlier analyses of sea-weed were of the ash rather than 
 of the entire plant. In many cases either the moisture con- 
 tent of the original 
 plant was not given, or 
 no distinction was made 
 between " pure " and 
 " crude " ash, on which 
 account it is impossible 
 to calculate the com- 
 position of the plants 
 from which the ash was 
 secured. On this ac- 
 count the number of 
 analyses of sea-weeds 
 in their natural condi- 
 tion is small, a fact that 
 is regrettable for the 
 reason that most of the 
 sea-weeds used for 
 manurial purposes, at 
 least in the United 
 States, are applied to 
 the soil without drying, 
 composting, or burning. 
 
 The analyses on the 
 opposite page by 
 Wheeler and Hartwell 
 show the composition of several different varieties, fol- 
 lowing the rinsing off of the salt water and the removal 
 of the superficial moisture. 
 
 93. The composition varies at different seasons. — 
 With but few exceptions, samples of sea-weed brought up 
 
 Fig. 3. — Sea-weed for Fertilizing. 
 
 Broad ribbon-weed, broad-leafed kelp, 
 
 devil's apron, tangle (Latninaria digitata). 
 
68 FERTILIZERS 
 
 by the tide and collected on the shore in January and 
 March were found to be richer in nitrogen, potash, and 
 phosphoric acid than those collected in September. This 
 may possibly be accounted for in part by previous partial 
 drying in the warmer month of September, on account of 
 
 Fig. 4. — Sea-weed for Fertilizing. 
 Dulse, dillisk (Rhodymenia palmata). 
 
 which the specimens suffered some loss by leaching either 
 in the sea-water or by falling rain. 
 
 94. Sea-weeds of chief importance in New England. — 
 Among the sea-weeds which are most abundant on the 
 New England coast, the Irish moss is one of the best. 
 This is followed in value by the dulse (dillisk), the flat- 
 stalked rock-weed, the round-stalked rock-weed, and 
 finally by the kelps. The other varieties of the algse 
 
SEA-WEEDS 
 
 69 
 
 mentioned are found in such small quantities as to be of 
 only minor agricultural importance. 
 
 95. The value of eel-grass. — The eel-grass, unlike 
 the algse, decomposes very slowly, and hence is not suitable 
 for the top-dressing of meadows. For the same reason 
 
 Fig. 5. — Sea-weed fob Fertilizing. 
 
 Round-stalked rock-weed (Ascophyllum, or Fucus, 
 
 nodosum). 
 
 it is less valuable when turned under as a manure, and it 
 may even act injuriously in such cases if used in large 
 quantities in a dry season. The best method of using it 
 is as litter for swine or other farm animals. 
 
 96. Value limited by distance of land. — The usual 
 limit of distance to which sea-weed has been carted inland 
 in the United States is from eight to ten miles, but even 
 
70 FERTILIZERS 
 
 then in some cases it is not profitable, if the teams and 
 laborers can be employed economically for other pur- 
 poses. 
 
 97. Practical utilization. — Such sea-weeds as decom- 
 pose most readily can be used for the autumn and winter 
 top-dressing of grass lands, provided they are not em- 
 ployed in such quantities as to smother the grass. As a 
 rule, however, they "can be used to the best advantage on 
 land which is about to be plowed. Sea-weeds are generally 
 considered preferable to stable manure in so far as con- 
 cerns their effect upon the smoothness of the potato crop ; 
 but in regard to the cooking qualities of the tubers, un- 
 favorable results from their use have been reported. It 
 has in fact been shown by experiments at the agricultural 
 experiment station in Rhode Island that the difference in 
 the smoothness of the tubers is due to the alkaline effect 
 of the farm-yard manure on the one hand, which creates 
 conditions favorable to the development of potato scab, 
 whereas common salt and other chlorids, such as are 
 associated with sea-weed, have the opposite tendency. 
 Furthermore, sea-weed itself would not exert an immediate 
 alkaline effect, like farm-yard manures. 
 
 98. Effect on the quality of certain crops. — As con- 
 cerns the effect of sea- weeds on the cooking quality and 
 the composition of the potato, it must be borne in mind 
 that if not leached they carry common salt, and that 
 Schultz (of Lupitz), Salfeld, and other German experimen- 
 ters have shown conclusively that the application of chlo- 
 rids, just before planting the potato crop, results in a 
 depression of the starch cont'ent of the tubers, increasing 
 at the same time their nitrogen content, and causing the 
 frequent development of a disagreeable soapy taste. 
 
 On account of the adhering sea- water, sea- weed may also 
 
SEA-WEEDS 71 
 
 be injurious to hops, to the burning quality of tobacco, 
 and it may depress the sugar content of beets. It is be- 
 cause of this well-recognized action that it has become 
 customary, in certain countries, to allow the sea-weed to 
 be leached by rains before carting it upon the land used for 
 farming purposes. The same result is often accomplished 
 in part on the coast of New England, without thought of 
 
 Fig. 6. — Sea-weed for Fertilizing. 
 Flat-stalked rock-weed (Fucus vesiculosus) . 
 
 this feature, by the practice in times of storm of carting 
 the sea-weed into piles a short distance from the shore, 
 until a favorable opportunity is presented for hauling it 
 away. This possible danger from the use of sea-weed 
 may be very largely or wholly obviated by applying it 
 either the autumn or winter previous to the time when 
 crops subject to such injury are to be grown. 
 
 99. Sea-weed quick in its action. — Owing to its 
 undergoing ready decomposition, sea-weed is to be classed 
 
72 FERTILIZERS 
 
 as a quickly acting manure, which exerts its chief effects 
 the first season. 
 
 100. Sea-weed compared with farm-yard manure. — 
 In the Western Islands, a load of farm-yard manure is 
 considered as being equal to two and one-half loads of 
 fresh sea-weed, or to one and three-fourths loads of sea- 
 weed which has lain in a pile for two months. 
 
 101. Sea-weed not a well-balanced manure. — It is 
 well recognized that sea-weed is not a well-balanced ma- 
 nure for all soils and crops, and that to supply the needed 
 amounts of phosphoric acid in sea-weed, in all cases, 
 would result in a frequent waste of potash or nitrogen, or 
 of both. On this account, sea-weed should be supple- 
 mented, especially where the cost of hauling is great, by 
 bone meal, basic slag meal, acid phosphate, or other phos- 
 phatic fertilizers. 
 
 102. Sea-weed as affecting the need of liming. — In 
 case sea-weeds are used frequently and they carry, attached 
 to them, a considerable quantity of the shells of mollusks, 
 these will supply more or less carbonate of lime, and 
 thus render liming unnecessary, whereas if they are very 
 free from shells, they may ultimately have the opposite 
 effect. 
 
 103. Freedom from weed seeds a great advantage. — 
 A strong point in favor of sea-weeds, as compared with 
 farm-yard manure, is their freedom from weed seeds. It 
 is stated that on this account farmers in certain sections 
 apply the farm-yard manure to their grass lands and re- 
 serve the sea-weed for their hoed crops. It is indeed 
 related by M. Herve Mangon l that on an island off the 
 coast of France (Noirmoutiers) cattle are kept in large 
 numbers, but the dung is dried and used as fuel ; the ashes 
 
 1 Comptes rend., 49 (Paris, 1859), 322. 
 
SEA-WEEDS 
 
 73 
 
 of the dung and the native sea-weeds being the only ma- 
 nures used there for centuries. 
 
 104. Composting sea-weeds. — The composting of sea- 
 weeds, as is frequently recommended in Europe, especially 
 in Sweden and other cold countries, is not usually con- 
 sidered economical in the United States on account of 
 the cost of labor involved in handling them. Sea-weeds 
 
 Fig. 7. — Sea-weed for Fertilizing. 
 Irish, or Carrageen, moss {Chondrus crispus). 
 
 are composted to a considerable extent on the coast of 
 Brittany, France ; and Turner tells of their being com- 
 posted in Devonshire, England, where they are often piled 
 in layers, each from 6 to 8 inches deep, with a quantity 
 of lime scattered between. The pile is then turned over 
 occasionally, and at the end of from two to three months, 
 when well rotted, it is ready for use. Sea-weeds are also 
 often composted with stable manure, but whatever the 
 method followed it is a wise plan to keep the pile covered 
 
74 FERTILIZERS 
 
 with at least a thin layer of moist soil, in order to prevent 
 the possible loss of ammonia. 
 
 105. Size and rapidity of growth of sea-weeds. — A 
 good idea of the rapidity of the growth of sea-weed is 
 furnished by an instance in Scotland where a rock, which 
 was uncovered only during the lowest tides, was chiseled 
 smooth in November and was thickly covered by the 
 following May with sea-weeds ranging in length from 2 
 to 6 feet. The growth of certain of the giant sea-weeds 
 of the Pacific coast and elsewhere must be exceedingly 
 rapid, for some of these plants are said to be annuals 
 propagated from spores ; and specimens of Nereocystis 
 luetkeana (Mertens) Postels and Ruprecht, for example, 
 have been observed, that were over 300 feet long. Further- 
 more, McFarland (Fertilizer Resources of the United 
 States, Senate Document No. 190, 62d Congress, 2d 
 Session) also reports them 100 feet in length. 
 
 The giant kelp (Macrocystis purifera, Turner) (Agardh.) 
 is said to be attached to the bottom by a holdfast which 
 reaches three feet in diameter. The stem at first branches 
 equally, but the later divisions grow to unequal lengths, 
 some of which often extend to from 300 to 700 feet ; and 
 in exceptional instances the total length of some of these 
 plants has been said to be fully 1500 feet. 
 
CHAPTER VII 
 
 GUANOS 
 
 The name "guano" is derived from the Spanish word 
 " Huano " which means dung. Its use for agricultural 
 purposes dates, according to Garcilaso de la Vega, from 
 the twelfth century, and in the year 1154 it is known to 
 have been carried to Edrisi in Arabia. The European 
 travelers Feuille, in 1710; Frezier, in 1713; and Ullao, 
 in 1740, all speak of the great value of guano as a manure. 
 
 106. Experimental trials of guano. — In 1804 Alexander 
 von Humboldt took some guano to Germany, where it 
 was examined chemically. At the instance of Sir John B. 
 Lawes experiments were conducted with it by General 
 Beatson at St. Helena in connection with the growth of 
 potatoes, with most beneficial results. In 1824 Skinner 
 of Baltimore received two casks of guano which served 
 to demonstrate its value in the United States. 
 
 107. Commercial introduction into Europe. — The first 
 attempts at the introduction of guano into Europe, in a 
 commercial way, in 1835 resulted in failure ; nevertheless 
 in 1840 Quiros Allier & Co. of Lima made a shipment to 
 Liverpool which was given a trial by the Royal Agricul- 
 tural Society. The results were so good that the company 
 made a six-year contract with the Peruvian government 
 for the exclusive export of guano. The contract was 
 signed on December 17, 1840, and in March of the follow- 
 ing year the shipment was begun. It was continued 
 
 75 
 
76 FERTILIZERS 
 
 with such success that by October of that year twenty- 
 three ship-loads had been sent to Europe. One of these 
 vessels carried to Germany the first consignments made 
 to that country. This was followed by a vessel load in 
 February, 1842. 
 
 Reports of the high prices received for the guano in 
 England soon caused the Peruvian government to with- 
 draw its contract and to enter into more favorable four- 
 year contracts with several firms. 
 
 108. The general nature of guano. — Guano is pop- 
 ularly supposed to consist exclusively of the excrement of 
 sea-fowl which roost upon the islands or mainlands in 
 great numbers, especially at night. Other common con- 
 stituents are the feathers, bones, and bodies of the birds 
 themselves, and the excrement and remains of large 
 marine animals, which not only visit the shores frequently, 
 but often die there by thousands, as may be seen by their 
 skeletons scattered over the guano. 
 
 109. The chemical composition of guanos. — The 
 frequent, penetrating odor of guano is due to the presence 
 of ammonia and of certain organic acids. Guano consists 
 chiefly of uric acid, oxalic acid, fatty acids, resinous 
 matter, guanin, organic matter rich in sulfur, phos- 
 
 Per Cent 
 
 Total nitrogen . 16.34 
 
 Ammonia already formed 14.08 
 
 Tricaleium phosphate 32.30 
 
 Potash 1.94 
 
 Lime 5.11 
 
 Magnesia 3.69 
 
 Sulfuric aeid 0.62 
 
 Chlorin 1.04 
 
 Soda 0.54 
 
 Iron oxid 0.18 
 
 Sand and silica 1.45 
 
 Water 17.13 
 
GUANOS 77 
 
 phoric acid united with lime and magnesia, ammonium 
 sulfate, potassium sulfate, sodium chlorid, potassium 
 chlorid, silicic acid, and sand. The table on the opposite 
 page is an analysis of guano by Karmrodt. 
 
 Guano differs widely from the dung of domestic fowl 
 in its greater percentages of nitrogen and of phosphoric 
 acid. This is caused by the fact that the sea-birds live 
 exclusively on .fish, which are rich in nitrogen and in 
 phosphate of lime, whereas the food of domestic birds con- 
 sists chiefly of cereals, which are relatively poor in these 
 ingredients. 
 
 110. Chemical composition affected by climatic con- 
 ditions. — The great variations in the composition of 
 guano are due to the widely varying climatic conditions 
 to which it is exposed. In a practically rainless climate 
 the naturally moist excrement dries quickly without under- 
 going material decomposition, in consequence of which 
 its natural content of nitrogen and of phosphoric acid is 
 still further increased. Such guanos usually contain 
 from 12 to 15 per cent of nitrogen and from 12 to 15 per 
 cent of phosphoric acid. The next poorer group generally 
 ranges in nitrogen from 5 to 7 per cent and in phosphoric 
 acid from 15 to 20 per cent. Finally, there is a group 
 with from 3 to 5 per cent of nitrogen and from 20 to 25 
 per cent of phosphoric acid. In regions of occasional 
 rainfall the nitrogen, which in the excrement is chiefly 
 in the form of uric acid, is changed by the action of mi- 
 croorganisms very largely into ammonia and ammonium 
 salts, which are readily leached away, together with the 
 potassium salts. In consequence, there finally results 
 a guano having a very low percentage of nitrogen and a 
 high percentage of phosphate of lime, such, for example, 
 as the Baker and Mejillones guanos. In humid regions 
 
78 FERTILIZERS 
 
 the process even goes so far that the nitrogeneous ma- 
 terials are not only entirely removed, but in some cases 
 a considerable part of the phosphoric acid undergoes 
 solution and subsequent transformation into phosphates 
 of iron and aluminum, as, for example, on the island of 
 Redonda. 
 
 111. Color and physical character. — The color of 
 guano is grayish-brown to yellowish-brown, the upper 
 layers being lighter and the deeper ones darker, the in- 
 tensity increasing usually with the depth. 
 
 The physical character of guano varies more or less in 
 different localities. 
 
 112. Chincha Island guano. — The Chincha Island 
 guano is said to be quite uniform and somewhat pulveru- 
 lent, but it contains many irregular pieces and lumps 
 ranging from three to, four inches in diameter down to 
 particles no larger than rape seed. These lumps, which 
 are whitish, grayish-white, reddish, or brownish, may 
 have a dull, crumbling, fatty, or crystalline appearance. 
 They are essentially concretionary in character, and from 
 their analysis it appears that they consist of potassium 
 sulfate; of ammonium, sodium, and potassium phos- 
 phates; calcium sulfate, ammonium urate, ammonium 
 oxalate, nitrogenous organic matter, and water. Some 
 of the lighter and softer specimens of non-crystalline 
 character have been found to contain as much as 14.8 
 per cent of nitrogen. In some cases they consist chiefly 
 of common salt and in others of ammonium phosphate. 
 It sometimes happens, also, that small accumulations of 
 whitish ammonium bicarbonate are found. These ma- 
 terials indicate the brief periodic existence of conditions 
 favorable to decomposition, such, for example, as might 
 be caused by an occasional slight fall of rain. 
 
GUANOS 79 
 
 113. Significance of oxalic acid and of oxalates in 
 guano. — The presence in guano of oxalic acid, usually- 
 combined as ammonium oxalate, is readily accounted for 
 by the fact that it is a decomposition product of uric 
 acid. For this reason when the uric acid content of guano 
 is high, the percentage of oxalic acid is usually low, and 
 vice versa. It was suggested by Liebig that the am- 
 monium oxalate might be an important factor, in con- 
 nection with ammonium sulfate, in effecting the solution of 
 the tricalcium phosphate of the guano ; whereby calcium 
 oxalate and ammonium phosphate would result. This 
 conclusion is justified, according to Heiden, only by labo- 
 ratory reactions. He does not consider it likely to take 
 place in this manner in the soil itself, owing to the absorp- 
 tive property of the soil for phosphoric acid and the tend- 
 ency of the latter to unite with iron and aluminum oxids, 
 which are normal constituents of most soils. 
 
 114. Influence on the physical character of soils. — 
 It cannot be expected that guano will have any long- 
 continued and marked influence upon the physical char- 
 acter of the soil, owing not only to the small amount 
 employed per acre, but also to the nature of the organic 
 matter which it contains. In this respect guano greatly 
 resembles human excrement. 
 
 115. The distribution and sources of guano. — The 
 chief source of guano has been the mainland and especially 
 a number of islands near the coast of Peru. These guanos 
 have been called Peruvian guanos, or else they have 
 received special names signifying the islands or the loca- 
 tions on the coast from which they were obtained. Promi- 
 nent among these islands are the Chinchas, Guanape, 
 Balestas Lobos, Potillos, and Macabi. Some of the 
 principal points on the mainland from which guanos have 
 
80 FERTILIZERS 
 
 been procured are Chipana, Huanillos, Pabellon de Pica, 
 Punta de Patillos, and Punta de Lobos. The many other 
 islands and inland points from which guano has been 
 secured are far too numerous to permit of their enumera- 
 tion. 
 
 From the shores and islands of Venezuela, Ecuador, 
 and Colombia, guano was exported at an earlier date under 
 the name of Colombian guano. Prominent among these 
 guanos were the " Monks " and " Maracaibo " guano, 
 from the coast of Venezuela, and the " Galapagos " 
 guano from the island of that name off the coast of 
 Ecuador. 
 
 From Bolivia (now a part of Chili) came the Bolivian 
 or Mejillones and several other guanos. 
 
 Guano is found on the islands of Roza and Patos on 
 the coast of Mexico and California, and in the Gulf of 
 Mexico on the islands of Curacoa, Aruba, and Navassa ; 
 also in the West Indies and in Labrador. On the west 
 coast of Africa guano is found in a number of places, 
 one of the best known of which is the island of Ichaboe 
 (Itschabo) ; it occurs also in Australia, Asia, and between 
 China and Japan, likewise at several points in Europe, 
 on the Jarvis and Baker islands, as well as on a large 
 number of islands belonging to other groups in the Pacific 
 Ocean. 
 
 The size -of some of these islands is very small. For 
 example, Baker Island is only 1914 yards long by 1210 
 yards wide, and it is less than 25 feet above sea level. 
 Jarvis Island is but 1870 yards in its greatest dimension 
 and but 1487 yards in the other, and it is but 30 feet above 
 sea level. These islands are nevertheless visited by enor- 
 mous numbers of birds, prominent among which are va- 
 rious species of Pelacanus. 
 
GUANOS 81 
 
 Recently, after supplying the needs of Cape Colony, 
 there have been occasional exportations of Ichaboe guano. 
 The material, however, is that which has been deposited 
 within the limits of a year and contains many undecom- 
 posed feathers. Its nitrogen content is about 8 per cent, 
 but it contains less phosphoric acid than similar grades 
 of Peruvian guano; it is also not so free as the latter 
 from foreign matter. In recent years considerable guano 
 ostensibly from the Chincha group of islands and from 
 the island of Lobos has been imported into the United 
 States, doubtless from the accumulations of recent years. 
 
 116. Adulteration of guano. — In the early days of 
 the trade in guano, many unprincipled middlemen found it 
 highly profitable to adulterate it. The following are some 
 of the materials which were employed for this purpose: 
 viz. water, carbonate of lime, gypsum, magnesium sul- 
 fate, sawdust, rice meal, common salt, sand, yellow loam, 
 and other materials of such a character as to prevent 
 their easy superficial recognition. In some cases low- 
 grade guano was mixed with the good grades. Owing to 
 the fact that there was at the outset no official inspection 
 of such materials, the way of the transgressor was exceed- 
 ingly easy. 
 
 117. "Rectified" or "dissolved" guano. — When gua- 
 nos are shipped to countries having a humid climate, 
 there is more or less danger, especially in the case of those 
 very rich in nitrogen, that they will absorb sufficient 
 moisture to induce fermentation and the formation of 
 ammonia. In the course of shipment, also, cargoes fre- 
 quently become moistened by sea-water with the result 
 that the urates become more or less broken down, a change 
 accompanied by the formation of ammonium carbonate, 
 which then undergoes ready dissociation, and consequent 
 
82 FERTILIZERS 
 
 loss of ammonia. In recognition of this loss and the lesser 
 value of such guano, its sale was for a long time forbidden 
 under the regulations of the Peruvian government. In 
 consequence, enormous quantities of it accumulated on 
 the docks, especially at Hamburg and Rotterdam. 
 
 Another reason for suppressing the sale of the damaged 
 guano was that the importers, whose trade depended 
 upon maintaining a high grade, hesitated to throw the 
 damaged product into the hands of middlemen who 
 would have been likely to sell it for, and in competition 
 with, the uninjured material ; thus destroying the con- 
 fidence of consumers and demoralizing the market. 
 
 In 1864 Ahlendorff & Co. made a contract with the 
 importers to handle this discarded material, and it was 
 dried by a process which was said to accomplish the reten- 
 tion of the ammonia. Soon after, this process was re- 
 placed by treatment with sulfuric acid, and for the first 
 time in the history of the sale of guano this firm offered 
 it under a fixed guaranty of nitrogen and phosphoric acid. 
 This treatment not only resulted in conserving the am- 
 monia, but it also increased the availability of the phos- 
 phoric acid. Both of these factors, and the definite 
 assurance as to its composition, together with the frequent 
 adulteration of the raw guano, soon resulted in its nearly 
 driving the raw guano from the market, and the demand 
 for the " rectified " product grew rapidly. 
 
 118. The manner of using guano. — Owing to its 
 ready decomposition and the consequent danger of losing 
 ammonia, the raw guano is better adapted for use where 
 it can be incorporated with the soil at the time of its 
 application, than as a top-dressing for grass or other 
 growing crops. The rectified guano is ideal, for the last- 
 mentioned purpose, for the reason that its ammonia is 
 
GUANOS 83 
 
 fixed by union with sulfuric acid, and much of the phos- 
 phoric acid is also capable of being readily dissolved and 
 carried into the soil. 
 
 119. Guano a poorly balanced manure. — Such guano 
 as is found in rainless regions is especially adapted to 
 agricultural needs for the reason that it contains not only 
 all three of the so-called essential elements, but, in addi- 
 tion, lime, magnesia, iron, sulfuric acid, and other ingre- 
 dients also occasionally of agricultural value. It is never- 
 theless true that the proportion of potash is often too low 
 to give the best results, for in the high-grade guano of 
 the Chincha group of islands, which contains about 12 
 to 16 per cent of nitrogen and 9 to 12 per cent of phos- 
 phoric acid, the content of potash ranges only from about 
 2.25 to 3.5 per cent. In the case of such guano, also, 
 the ratio of phosphoric acid to nitrogen is too low to 
 make the most economical and best-balanced manure for 
 certain crops and soils. Again, the Lobos guano frequently 
 contains as much as from 24 to 27 per cent of phosphoric 
 acid and as little as from 2 to 3 per cent of nitrogen, with 
 even less potash than is contained in the Chincha guano ; 
 hence it is obvious that considerable additions of nitrogen 
 and potash must be made in order to make it an ideal 
 fertilizer for most crops and conditions. 
 
 120. Bat guano unlike Peruvian and other guanos. — 
 The so-called bat guano should not be confused with 
 Peruvian guano, since, on account of the character of the 
 food of the animal producing it (a mammal), it differs 
 widely, even under the most favorable conditions, from 
 the guano produced by birds living exclusively on fish. 
 
 121. Appearance of bat guano. — The fresh excrement 
 of the European bat resembles in form that of the mouse, 
 but it is not so compact, and it presents a glistening appear- 
 
84 FERTILIZERS 
 
 ance on account of the presence in it of undigested insect 
 wings and other residues. Bat guanos are usually pul- 
 verulent and are ordinarily quite dry and odorous ; some- 
 times, however, they occur as heavy, doughy, inodorous 
 masses. 
 
 122. Where bat guano is found. — The bat is a vora- 
 cious eater and hence accumulates large quantities of 
 dung in caves, grottos, church steeples, and similar dark 
 and obscure places to which it can gain access. 
 
 123. Chemical composition of bat guano. — The fresh 
 dung is said by Hardy to contain about 60 per cent of 
 water, but in bat guano the amount of water usually 
 ranges from 12 to 25 per cent. The content of nitrogen 
 may range from 1 to 12 per cent, the greater portion of it 
 being present in ammonium salts associated with small, 
 or occasional large, quantities of nitrates and more or less 
 nitrogen in organic matter. The quantity of phos- 
 phoric acid is also widely variable, the minimum being 
 about 2.5 per cent, and the maximum about 16 per cent. 
 The presence of large amounts of nitrates, in some cases, is 
 attributed to the material having rested on limestone 
 rock at points where there is ready access of air and at 
 least a fair amount of moisture. Like all such materials, 
 they often contain considerable earthy matter. 
 
 124. Distribution of bat guano. — Deposits of bat 
 guano are widely distributed in North America, the 
 West Indies, Spain, Sardinia, France, the islands of the 
 Indian Ocean, and elsewhere. Some of the most extensive 
 deposits in the United States have been found in Texas 
 and Arkansas ; a single deposit in some of these cases 
 amounting to as much as 20,000 tons. 
 
 125. Precautions in the use and purchase of bat guano. 
 — From what has preceded it will be seen that bat guano 
 
GUANOS 
 
 85 
 
 varies as widely in composition as the ordinary guanos 
 from the rainless and more or less rainy regions. The 
 best specimens approach in nitrogen content the Chin- 
 cha and other high-grade guanos, whereas the poorest 
 contain even less nitrogen than the Lobos guano. The 
 usual amount of phosphoric acid present is from 3 to 7 
 per cent, although it sometimes reaches an upper limit of 
 16 per cent, as, for example, in a quite fresh deposit in 
 Arkansas. The content of potash is usually very low, 
 rarely exceeding 2 per cent, and it is frequently less than 
 1 per cent. The following are averages given by Goess- 
 mann : — 
 
 Nitrogen . . 
 Potash . . . 
 Phosphoric acid 
 
 Average of Nine 
 
 Samples of Bat 
 
 Guano from Texas 
 
 6.47 
 1.31 
 3.76 
 
 Average of Two 
 
 Samples of Bat 
 
 Guano from Florida 
 
 9.74 
 1.77 
 3.35 
 
 It is evident from the foregoing that such guano should 
 be bought and sold solely on the basis of its chemical 
 analysis. 
 
 126. Bat guano needs supplementing. — In most cases 
 these guanos must be supplemented by applications of 
 potassium salts and by readily available phosphatic 
 fertilizers, if they are to be used in the most economical 
 way. 
 
CHAPTER VIII 
 
 FISH, CRAB, LOBSTER, AND SIMILAR WASTES 
 
 The term " fish guano " is often applied to fish and 
 fish wastes, but since it is in no strict sense guano, as im- 
 plied by the Spanish origin of the name, it is more properly 
 considered under a separate chapter. 
 
 127. Fish long used as a fertilizer. — The use of fish 
 and of fish waste as a fertilizer by people living near the 
 ocean, or wherever fisheries flourish, has long been prac- 
 ticed. In fact, the American Indian was no exception, for 
 he had already learned to apply fish as a fertilizer for his 
 maize when the Europeans first landed on the shores of 
 North America. 
 
 128. Early catching of fish for fertilizer purposes. — 
 As early as 1872 the catching of fish, which were employed 
 for fertilizing the soil for both wheat and hops, had become 
 quite an industry on the coasts of Essex, Kent, and Sussex, 
 in England. The fish, which were very small, were a 
 variety of herring (Clupea sprattus). They were sub- 
 jected to a stamping and crushing process and were ap- 
 plied to the soil without further preparation. 
 
 129. Special processes for preparing fish for fertilizer 
 uses. — In 1853 Petlitt patented a process for the prep- 
 aration of a fertilizer from herring. The nitrogen con- 
 tent of this prepared material ranged from about 11.2 to 
 13.8 per cent. 
 
 Shortly after the middle of the preceding century 
 Ch. de Molon, who had already convinced himself by 
 
 86 
 
FISH, CRAB, LOBSTER, AND SIMILAR WASTES 87 
 
 practical trials on his estate on the coast of Brittany of 
 the manurial value of the wastes from the sardine fisheries, 
 conceived the idea of treating the material in such a way 
 as to prevent its rapid decomposition and render it trans- 
 portable to long distances. To this end De Molon as- 
 sociated with himself Thurneyssen, and they erected a 
 factory near Brest, in which to carry out the process. 
 This, in brief, consisted in heating the fish with steam 
 applied between the walls of a double-walled kettle at a 
 pressure of three and one-half atmospheres (140° C), 
 after which it was pressed. In this process the amount 
 of oil recovered from the top of the waste liquors repre- 
 sented about 2 to 2.5 per cent of the fresh fish. The 
 waste liquors, because of their high nitrogen content, some- 
 times created a nuisance, on which account they were 
 often evaporated, whereby the solid matter was saved. 
 The remaining cake was passed through a machine which 
 rubbed it into a thick dough, in which state it was taken 
 to the drying room and subjected to a temperature of 
 from 48° to 56° R., until it was ready for grinding, in 
 final preparation for shipment. The dry product ready 
 for marketing represented about 22 per cent of the original 
 weight of fish. 
 
 130. Fish wastes in Japan. — In Japan herring are 
 likewise utilized for the manufacture of oil and fish-scrap, 
 the latter being used without further manipulation, in 
 fertilizing tea plants, tobacco, cotton, and other crops. 
 
 131. Fish wastes in Newfoundland. — In connection 
 with the Newfoundland cod fisheries, the heads, entrails, 
 bones, and other waste portions of the fish, to the amount 
 of 700,000 tons annually, were cast into the sea until De 
 Molon sent his younger brother to the Island to erect a 
 factory for the preparation of fish guano for export. 
 
88 FERTILIZERS 
 
 132. Norwegian wastes from cod and whales. — In 
 Norway fish guano is prepared from the wastes of the cod- 
 fishing industry and from whales. The number of cod- 
 fish said to be taken annually in that country amounts to 
 from 18,000,000 to 20,000,000. A considerable number 
 of factories are engaged in the preparation of the waste 
 for fertilizing purposes. The finished product has a white 
 to brown color and usually contains from 8.5 to 11 per 
 cent of water, 8 to 10 per cent of nitrogen, and 12 to 14 
 per cent of phosphoric acid. 
 
 133. Methods of handling Menhaden in the United 
 States. — The method of handling the Menhaden (a sort 
 of herring also called pogys, Aha menhaden) now prac- 
 ticed in the United States, varies somewhat in the differ- 
 ent works. In some places the former method of unloading 
 from vessels by means of tubs holding 3| barrels, or about 
 1000 fish, is still in vogue. By that method from 80,000 
 to 100,000 fish can be discharged per hour. The tubs are 
 raised by means of a steam hoister installed on the steamer 
 and used in raising to the deck the fish caught in the seines. 
 In certain instances, also, they are raised by hoisters located 
 at the dock. From the tubs the fish are passed to a re- 
 ceiving box, from which they are taken into cars. They 
 are then hauled up an inclined track by another hoister 
 and delivered into wooden vats, well provided with steam 
 pipes. Each of these vats holds about 20,000 fish. Here 
 they are cooked until they are ready for pressing in power- 
 ful hydraulic presses which leave a product containing 
 from 50 to 60 per cent of moisture. The scrap is then 
 either treated with sulfuric acid, in order to prevent its 
 decomposition, or it is sun-dried on platforms. At present 
 most of the factories are equipped with elevators which 
 transfer the fish to the receiving boxes and conveyors at 
 
FISH, CRAB, LOBSTER, AND SIMILAR WASTES 89 
 
 the rate of 250,000 or more per hour, for each elevator in 
 operation. From the elevator the fish are carried into 
 iron cookers of various sizes, which are from 20 to 30 feet 
 long, and from 2 to 3 feet in diameter. The fish pass 
 through these cylinders, subjected to a continual steam 
 pressure of 100 pounds to the square inch, at the rate of 
 from 100,000 to 150,000 per hour ; they then pass, by a 
 conveyor, directly into screw presses of various sizes. 
 The larger presses now in use have a capacity of 150,000 
 fish per hour. Upon leaving the presses the scrap is 
 carried, largely by means of conveyors of various types, 
 to the acidulated scrap storage or to the dryers, as desired. 
 In some cases the scrap is treated with sulfuric acid and is 
 then transferred directly to vessels lying alongside of 
 those which are discharging the fish. 
 
 134. Fish waste treated with sulfuric acid. — Attempts 
 have been made to treat the fish waste with considerable 
 quantities of sulfuric acid, but this has proved to be a very 
 difficult operation ; and in but few instances is the char- 
 acter of the fish products such that this treatment is 
 considered practical. The amount of water in such treated 
 material may range from 13 to 18 per cent, the total nitro- 
 gen from 7 to 9 per cent, and the total phosphoric acid 
 often from 1 1 to 12 per cent. By this treatment two-thirds 
 of the phosphoric acid is rendered immediately soluble in 
 water. A part of the nitrogen may be changed into 
 ammonia, and, under the usual conditions, about one-third 
 of it is thus changed. 
 
 135. Chemical composition and utilization of whale 
 products. — Fresh whale-meat contains about 44 per cent 
 of water, 23 per cent of fat, 32 per cent of flesh, and 1 per 
 cent of ash. In its undried condition it contains about 
 4.8 per cent of nitrogen, but when fully dried the nitrogen 
 
90 FERTILIZERS 
 
 content is about 8.7 per cent. The whale-bone, with a 
 content of 3.84 per cent of water, contains 1.3 per cent of 
 fat, 34.6 per cent of organic matter, and 60.2 per cent of 
 ash. The nitrogen amounts to 3.5 per cent. In the man- 
 ufacture of fertilizer from the bones and meat of whales, 
 the fat content is so great that many difficulties are met 
 in making the separation. The whale glue which is 
 unfit for other purposes finds its way into fertilizers. It 
 contains approximately 8.4 per cent of nitrogen and 3.2 
 per cent of phosphoric acid. Whale flesh, when dried and 
 freed from fat, contains from 14 to 15 per cent of nitrogen. 
 A so-called " whale guano," with from 7 to 8 per cent of 
 nitrogen and 9 to 10 per cent of phosphoric acid, and whale- 
 bone meal with 4 per cent of nitrogen and 21 per cent of 
 phosphoric acid, have been offered in the market. 
 
 136. Availability and use of fish guano. — The avail- 
 ability of the nitrogen of fish guano stands close to that of 
 dried blood. Like all such organic nitrogenous materials, 
 the nitrogen is not so quick in its action as that in nitrate 
 of soda, potassium nitrate, or even in sulfate of ammonia. 
 There are several important conditions upon which its 
 transformation into nitrates and its consequent efficiency 
 very largely depends; as, for example, the temperature, 
 moisture, soil reaction, the fungi, and the bacterial flora 
 of the soil. Because of the several conditions necessary 
 to the transformation of the nitrogen of such materials 
 into ammonia and eventually into nitric acid, it is 
 usually best to incorporate it with the soil rather than 
 to use it as a top-dressing. Though not absolutely nec- 
 essary, it is desirable that fertilizer ingredients of this 
 • character, if applied in large quantities, should be incorpo- 
 rated with the soil several days before the seed is planted. 
 In this way possible injury to the plant seedlings, which 
 
FISH, CRAB, LOBSTER, AND SIMILAR WASTES 01 
 
 might arise in connection with the processes of fermenta- 
 tion, may be avoided. 
 
 137. Fish guano requires supplementing. — Owing to 
 the high percentage of nitrogen present in fish guano, it 
 should usually be applied in conjunction with bone, or 
 preferably with basic slag meal or with acid phosphate, or 
 other superphosphates. It is usually important, also, that 
 it be properly supplemented with suitable potassium salts. 
 
 138. Fish scrap may be employed without further 
 treatment. — As a rule the fish scrap is sold directly to 
 fertilizer manufacturers, but whenever it and the waste 
 untreated fish or parts of fish are obtainable at low cost, 
 near where they can be utilized, they can be employed 
 advantageously bj r spreading them on the surface of 
 the land and plowing them under as one would use 
 stable manure. 
 
 139. The value of fish waste depends on the climate 
 and soil. — It is reported by Kellner that in certain parts 
 of Japan fish scrap, owing to the warm climate, moisture, 
 and other conditions favorable to decomposition, is a 
 quick-acting fertilizer ; but in very cold countries, where 
 the reverse conditions prevail, its action is slow and is 
 especially unsatisfactory early in the spring. For many 
 reasons such material is much better adapted for use on 
 sandy or naturally open soils than on compact silts and 
 clays. 
 
 140. Shrimps. — Along the coast of the North Sea 
 there are found millions of shrimps (Crangon vulgaris), 
 which, though prized as a great delicacy for human food, 
 are used at times in great quantities in the manufacture 
 of fertilizer. Since the product is relatively poor in phos- 
 phoric acid, it is often supplemented by additions of bone 
 or of other phosphatic fertilizers. 
 
92 FERTILIZERS 
 
 141. The king-crab. — In the United States the king- 
 crab (also known as horse-foot or horse-shoe ; Limulus 
 Americanus) has not only been utilized directly as a fer- 
 tilizer, but it has also been dried, ground, and sold under 
 the name of " horse-foot guano." It has often been used 
 as an ingredient of various commercial fertilizers. In 
 a dry state this material contains, as found by Voorhees, 
 about 10 per cent of nitrogen, which apparently possesses 
 a high degree of availability. According to Storer, it is 
 necessarily poor in phosphoric acid, as is shown by the 
 fact that the dried shells, after being freed of the flesh 
 attached to the upper portions and to the legs, contained 
 but 0.26 per cent of phosphoric acid. They contain only 
 0.06 per cent of potash, but the content of nitrogen has 
 been found to be equal to as much as 12.55 per cent. 
 
 142. The common crab. — According to Storer, the 
 common crab (Lupa dicantha Milne-Edwards) collected 
 on the shore of Massachusetts was found to contain 3.6 
 per cent of phosphoric acid, 0.2 per cent of potash, and 
 1.95 per cent of nitrogen. 
 
 143. Lobster refuse. — The shells of cooked lobsters 
 (Homarus Americanus Milne-Edwards), are reported by 
 Voorhees as containing, when dry, an average of 3 per 
 cent of phosphoric acid, 20 per cent of lime, and 4 per 
 cent of nitrogen. An analysis of lobster shells reported 
 by Goessmann, shows that they contained 7.3 per cent of 
 water, 4.5 per cent of nitrogen, 3.5 per cent of phosphoric 
 acid, 22.2 per cent of lime, and 1.3 per cent of magnesia. 
 
 144. Star-fish. — In the case of fresh star-fish examined 
 at the Rhode Island experiment station it was found, after 
 rinsing with fresh water and removing the superficial 
 moisture, that they lost, upon drying, 64.4 per cent of 
 their weight. The mineral matter remaining after they 
 
FISH, CRAB, LOBSTER, AND SIMILAR WASTES 
 
 93 
 
 were incinerated, amounted to 20.3 per cent. The fresh 
 undried star-fish contained 9.62 per cent of lime, 0.23 per 
 cent of potash, 0.20 per cent of phosphoric acid, and 1.8 
 per cent of nitrogen. The value of these ingredients in a 
 ton of fresh star-fish, based upon the recent ruling prices 
 for lime and the other ingredients, would range from about 
 $6 to $7.50 per ton. 
 
 It is reported that on the French and Belgian coasts of 
 the North Sea a mixture of certain mollusks with star-fish 
 is employed as a manure, under the name " Coquilles 
 animalisees." 
 
CHAPTER IX 
 
 COMMON SLAUGHTER-HOUSE NITROGENOUS WASTE 
 PRODUCTS 
 
 The number of waste nitrogenous animal substances is 
 so large, and they are so important, that they demand 
 individual mention. 
 
 145. Dried meat meal. — Among the trade names which 
 have been applied to various preparations of dried meat 
 meal are " animal matter," " dried meat," " azotin," and 
 " ammonite." These materials are produced in the process 
 of rendering dead animals, meat refuse, and as a waste 
 product from the manufacture of meat extract. In the 
 preparation of such extracts much of the phosphoric 
 acid is removed, on which account certain Australian prod- 
 ucts have been placed on the market mixed with bone 
 meal. These contain about 6 per cent of nitrogen and 
 about 13 per cent of phosphoric acid. 
 
 The rendering process. — In the rendering process refuse 
 bones and meat are placed in steel tanks where they are 
 subjected for a few hours to a steam pressure of from 40 
 to 60 pounds, or higher. As a result of this treatment the 
 fat is separated and the bones are rendered highly friable, 
 in consequence of which they can be easily ground. After 
 the removal of the hot liquors the fat rises to the surface 
 of the liquid, where it solidifies upon cooling ; the meat is 
 also separated from the bones, after which it is dried and 
 ground. 
 
 94 
 
SLAUGHTER-HOUSE WASTE PRODUCTS 95 
 
 146. All readily utilized by fertilizer manufacturers. — 
 Before the manufacture of fertilizers had grown to its 
 present proportions, these meat residues were readily avail- 
 able to the farmer, but now that the supply fails to keep 
 pace with the demands, the manufacturers of " complete " 
 fertilizers readily absorb the entire supply. 
 
 147. Chemical composition of meat meal. — The 
 amount of nitrogen in the best of the meat meals ranges 
 usually from 13 to 14 per cent ; though they may contain 
 as little as 10 per cent, according to the amount of im- 
 purities and moisture present. In addition to nitrogen 
 the meat meals contain varying percentages of phosphoric 
 acid, depending in amount upon their origin and the quan- 
 tity of bone associated with the meat. 
 
 148. Availability of meat meal. — In the availability 
 of their nitrogen, these waste meat materials stand, accord- 
 ing to Wagner, somewhat behind dried blood, horn meal, 
 and tender plants, and on about the same plane as nitrogen 
 in fish guano, bone, and bone tankage ; hence they stand 
 in the next to the best group of organic nitrogenous ma- 
 nures. 
 
 149. The nature of bone tankage. — Bone tankage 
 consists of rendered or steamed bone associated with a 
 considerable quantity of meat, cartilaginous matter, and 
 other substances. It is prepared from the animal refuse 
 secured from slaughter-houses and meat markets. 
 
 150. Composition of bone tankage. — Its nitrogen 
 content may range from 4 to 12 per cent and its content 
 of phosphoric acid from 7 per cent to approximately 20 
 per cent. In the United States six commercial grades are 
 often recognized with 18, 16, 13.5, 11.5, 9, and 7 per cent 
 as the respective minimum percentages of phosphoric acid. 
 It is obvious that these are mere arbitrary subdivisions, 
 
96 FERTILIZERS 
 
 and that any one grade must range up to the next higher 
 just as the highest of the bone tankages range up to the 
 minimum of what is recognized in the trade as bone. 
 
 151. Value of bone tankage as a fertilizer. — The value 
 of bone tankage as a fertilizer depends to a considerable 
 extent upon its degree of fineness. The importance of 
 this feature is greater, the larger the quantity of bone, 
 and consequently the higher the percentage of phosphoric 
 acid. It is probable that the fertilizing value of the nitro- 
 gen in bone tankage does not differ materially from that 
 in bone, fish, and meat meal, and it should logically stand 
 between the first two. 
 
 152. Method of employment. — The best method for 
 the employment of bone tankage is to introduce it into the 
 soil in finely ground form, rather than to use it in a coarse 
 condition or to employ it as a top-dressing. 
 
 153. Chemical composition of red dried blood. — The 
 red dried blood, which differs from the black blood in its 
 method of preparation, possesses ordinarily the higher 
 commercial value, and usually contains from 13 to 14 per 
 cent of nitrogen, though if imperfectly dried it may con- 
 tain much smaller percentages. 
 
 154. Chemical composition of black dried blood. — 
 Black dried blood as commonly offered in the market may 
 range in nitrogen content from 5.5 to 12 per cent, and es- 
 pecially good lots have been found to contain over 13 per 
 cent. 
 
 155. Reasons for occasional low nitrogen content of 
 blood. — The low content of nitrogen sometimes found in 
 dried blood may be due to. the incidental or intentional 
 introduction, in the course of its handling and manufac- 
 ture, of more or less bone and tankage. It may also be 
 due to its adulteration with pulverized roasted leather, 
 
SLAUGHTER-HOUSE WASTE PRODUCTS 97 
 
 pulverized peat, or other substances, the detection of 
 which, by casual inspection, and even in some cases by 
 chemical or other means, has heretofore been difficult or 
 impossible. If the blood contains much tankage or bone, 
 there will be much more phosphoric acid present than the 
 small quantity normally associated with pure blood. 
 
 156. Chemical composition of the better commercial 
 blood. — The better grades of commercial dried blood 
 usually contain from 13 to 14 per cent of water, from 10 
 to 13 per cent of nitrogen, 0.5 to 1.5 per cent of phos- 
 phoric acid, and from 0.6 to 0.8 per cent of potash, 
 though it is ordinarily sold without reference to any- 
 thing but its nitrogen content. 
 
 157. Crystallized blood. — What is known as "crys- 
 tallized " dried blood is produced by evaporation at a 
 temperature of about 60° C, and it is capable of being 
 redissolved. Owing to its cost, it is usually employed for 
 industrial rather than fertilizing purposes. 
 
 158. Certain processes of preparing dried blood. — In 
 the process of transforming blood into the dried market- 
 able material, it is agitated vigorously and is at the same 
 time treated with steam in a vessel with a perforated false 
 bottom. As a result of the raised temperature, coagula- 
 tion of the fibrin and albumen takes place, after which the 
 slightly reddish liquid portion is withdrawn. After dry- 
 ing, the blood is milled to a proper degree of fineness. 
 The yield of dried blood is above 20 pounds per 100 pounds 
 of the original material. The coagulation is often has- 
 tened by the addition of a small amount of concentrated 
 sulfuric acid. Sometimes from 2 to 3 per cent of pul- 
 verized quicklime is added to the blood before flocculating. 
 In consequence of this addition, any ammonia in the waste 
 water is disengaged, and the material can then be dried in 
 
98 FERTILIZERS 
 
 the air, if desired, with the result that a practically odor- 
 less fine powder is produced. 
 
 If blood is allowed to stand for some time, after adding 
 from 1.3 to 3 per cent of lime, the mass will solidify and 
 can be subsequently air-dried with ease and without under- 
 going decomposition. 
 
 In the process of drying and preparing dried blood, a 
 mixture of iron sulfate, sulfuric acid, and sodium nitrate 
 is often added. The coagulation in such cases is very 
 rapid, and the material gives off no bad odors during the 
 process of drying. It is not practical for this purpose to 
 use solely the commercial iron sulfate, for if this is done 
 there results a pasty mass which does not dry readily. 
 In order to obviate this difficulty, a mixture of sulfate of 
 iron and of alum is sometimes employed ; also treatment 
 of the blood with calcium carbonate (chalk) and peat ; 
 and precipitation with alkaline sulfates or phosphates 
 and acid ferric sulfate. 
 
 159. Dried blood, if very fine, is highly hygroscopic. — 
 The finer the blood is ground, the more hygroscopic it 
 becomes, and when made excessively fine the water con- 
 tent has been known to reach 27 per cent. This high 
 moisture content is, however, not desirable in material 
 which must be stored, for too much moisture is likely to 
 lead to changes resulting finally in a loss of ammonia. 
 
 160. Availability of blood dependent upon soil condi- 
 tions. — Dried blood is the best, or one of the best, organic 
 nitrogenous fertilizers, but like others it is dependent for 
 its efficiency upon the character of the soil. This is well 
 shown by experiments made with it on upland silt loam 
 soil, at the Rhode Island experiment station, in which the 
 availability of the nitrogen in an excellent lot of black 
 dried blood, containing slightly over 13 per cent of nitro- 
 
SLAUGHTER-HOUSE WASTE PRODUCTS 99 
 
 gen, was considerably less than one-half as great as in 
 nitrate of soda, whereas after liming the soil, the avail- 
 ability of the nitrogen rose to over 90 per cent of that in 
 nitrate of soda. 
 
 161. Processes of preparing horn meal and hoof meal. 
 — In the various manufacturing establishments where 
 horn is employed, there is a large lot of waste material. 
 The preparation of such horn waste, and of hoofs, for fer- 
 tilizing purposes, is sometimes accomplished by subjecting 
 them for about twelve hours to steam pressure, after which 
 the material is dried and ground to a fine powder. It is 
 then sold as horn meal and hoof meal. Another method 
 of manufacture is to subject the materials to high tempera- 
 tures, even frequently to the extent of slight roasting, 
 after which they can be easily pulverized. In consequence 
 of the loss of water in this process the nitrogen content is 
 raised materially. 
 
 162. The chemical composition of horn meal. — A 
 very pure sample of horn meal is reported as containing 
 9.5 per cent of water, 87.4 per cent of organic matter, and 
 1.69 per cent of ash, in addition to small amounts of 
 impurities. 
 
 The amount of nitrogen present in horn (in keratin) is 
 about 14.1 per cent, phosphoric acid 0.28 per cent, and lime 
 0.48 per cent. 
 
 Certain English writers report the range of nitrogen in 
 commercial samples of horn meal to be from 7 to 15 per 
 cent. 
 
 163. Chemical composition of horn and hoof meal. — 
 A sample of mixed horn and hoof meal, from a lot in which 
 hoofs were used which had a small amount of bone adher- 
 ing to them, was found by C. Peterson to contain 13 per 
 cent of nitrogen and 5.5 per cent of phosphoric acid. 
 
100 FERTILIZERS 
 
 Samples are reported from France as containing from 16 
 to 17 per cent of nitrogen. The analyses of three different 
 lots of hoof and horn meal are reported by Goessmann in 
 which the minimum of nitrogen was 1 1 per cent and the 
 maximum 15.5 per cent. 
 
 164. The nitrogen content of hoof meal. — The average 
 nitrogen content of hoof meal is generally held to be about 
 12 per cent. 
 
 165. The efficiency of hoof meal. — Hoof meal in its 
 natural condition is held by Voorhees, Murray, and others 
 as being of little value, even though finely ground ; and 
 some authorities assert that even after steaming, the value 
 of the nitrogen is still far below that in blood and tankage. 
 It is nevertheless superior to leather, wool waste, and hair, 
 and Heiden ranks it as a very effective nitrogenous fer- 
 tilizer (Dtingerlehre, 2, 746). 
 
 166. The adulteration of horn and hoof meals. — It is 
 reported that horn meal and hoof meal are sometimes 
 adulterated with ground nut shells and other difficultly 
 recognizable sustances. On this account, in purchasing 
 such materials, one should buy only on the basis of a 
 guaranteed analysis. The adulteration may explain 
 much of the discordant testimony as to the agricultural 
 value of these materials, for it does not appear that the 
 genuineness of the lots employed in certain experiments 
 was always determined. 
 
 167. Preparatory treatment of waste leather. — Large 
 quantities of leather waste are now said to be employed 
 in the manufacture of ready-mixed fertilizers. In its 
 preparation for such use a wet acid or " chamber " pro- 
 cess, involving a simultaneous treatment of raw phosphates, 
 is applicable, as it is under certain conditions to many of 
 the other waste nitrogenous materials. Waste leather is 
 
SLAUGHTER-HOUSE WASTE PRODUCTS 101 
 
 also treated with steam, in the same way as hoof meal and 
 horn meal. It is then dried and ground, or in lieu of 
 steaming it is often roasted and ground. The value of 
 such prepared leather, unless it is subjected to the " cham- 
 ber " process, is very small in any case, although it is 
 slightly greater if steamed than if roasted. Owing to the 
 destruction of the tannin in the roasting process, the 
 leather thus prepared is said to be selected as an adulter- 
 ant of dried blood and of certain other high-grade nitro- 
 genous substances, on account of the difficulty of its 
 recognition. 
 
 168. The chemical composition of prepared leather 
 waste. — The leather meal prepared by the steaming or 
 roasting processes contains from 7 to 9 per cent of nitro- 
 gen and from 0.5 to 1 per cent of phosphoric acid; al- 
 though it may sometimes range slightly above or below 
 these figures. 
 
 169. The availability of nitrogen in leather. — If em- 
 ployed on a soil in which the conditions for nitrification 
 are poor, the value of the nitrogen of roasted leather may 
 be even less than one-hundredth as great as that of the 
 same quantity in nitrate of soda ; if, however, the condi- 
 tions for nitrification are ideal, its value may rise to from 
 13 to 20 on the basis of 100 for the nitrogen in nitrate of 
 soda. At all events, such leather is one of the least valu- 
 able of the nitrogenous fertilizers. It is obvious, therefore, 
 that roasted or steamed leather meal, if employed directly 
 as a fertilizer, is not worth the cost of transporting to very 
 great distances. It is, however, probable that by the sul- 
 furic acid or " chamber " process a considerable part of 
 the nitrogen is changed into sulfate of ammonia and that 
 the organic residues remaining are also rendered still more 
 available to plants. 
 
102 FERTILIZERS 
 
 170. Treatment of leather with carbonates of the al- 
 kalies. — It has been proposed by Reichardt to treat 
 waste leather with carbonates of the alkalies. Before 
 being subjected to such treatment, powdered leather was 
 found to be soluble in hot water to the extent of but 15.8 
 per cent, but after being left in contact with a 5 per cent 
 solution of sodium carbonate for several days, it was 
 soluble to the extent of 28.8 per cent. This method of 
 treatment has, however, apparently never found any exten- 
 sive application in practice. 
 
 171. Leather really not so valuable as it appears. — 
 The inefficiency of the nitrogen in leather meal, as com- 
 pared with that in the better class of nitrogenous materials, 
 is not shown adequately by merely the smaller weights of 
 the resultant crops, since crops grown with the aid of an 
 abundance of readily available nitrogen are often richer 
 in that element, and hence possess a greater feeding value 
 than those grown with poorer and less available materials, 
 like leather. This is well illustrated by experiments by 
 S. W. Johnson in which nitrogen in blood, at the rate of 
 20 pounds per acre, gave four times as great an increase 
 in crop as the same amount of nitrogen in horn. The in- 
 crease of nitrogen in the crop was also nearly twice as great 
 in the former as in the latter case. With 40 and 60 pounds 
 of nitrogen per acre, the same principle held true, although 
 the proportionate increases were not the same as in the 
 first instance. 
 
CHAPTER X 
 
 OTHER MISCELLANEOUS NITROGENOUS SUBSTANCES 
 
 A considerable number of plant residues and of other 
 miscellaneous materials of somewhat uncommon occur- 
 rence are often used for manurial purposes. These will 
 now be considered. 
 
 172. Feathers. — Clean feathers, according to the analy- 
 ses of Payen and Boussingault, contain 15.3 per cent of 
 nitrogen. The sweepings from a feather warehouse, how- 
 ever, contained but 6.25 per cent of nitrogen, indicating 
 the presence of much foreign matter. 
 
 Feathers decompose slowly in the soil, and hence they 
 have a small positive value as a fertilizer, even without 
 special treatment. 
 
 173. Hair bristles and wool. — The hair of various 
 animals, the bristles of swine, and wool all contain es- 
 sentially the same amounts of nitrogen as feathers. In 
 other words, if free from all impurities, they contain from 
 14 to 15 per cent of nitrogen. After drying at 250° F., 
 human hair has been found to contain 17 per cent of 
 nitrogen. 
 
 174. Tannery hair. — Hair from tanneries contains more 
 or less foreign matter and water, which lessen the nitro- 
 gen content. The amount of nitrogen found in such hair 
 ranges from 5.5 to 8 per cent, the average being about 6.5 
 per cent. Certain of the calcareous wastes of the tanner- 
 ies, charged with organic matter derived from the cleans- 
 
 103 
 
104 FEETIL1ZEE8 
 
 ing and preparation of hides, contain from 2.8 to 3.4 per 
 cent of nitrogen. 
 
 175. Waste silk. — The nitrogen content of waste silk 
 and silk rags ranges from 8 to 11 per cent of nitrogen, 
 depending upon the purity of the materials. 
 
 176. Wastes from hares and rabbits. — In the prep- 
 aration of the hair of hares and rabbits for the manufac- 
 ture of hats, the ears, tails, legs, and irregular parts of 
 the skin often accumulate in considerable quantities as 
 waste matter. This material, according to C. Thiel, has 
 been found to contain 7 per cent of nitrogen, 0.6 per cent 
 of potash, and 1.7 to 3.1 per cent of phosphoric acid. 
 
 177. Chemical composition of waste wool. — Wool 
 waste may contain from 0.5 to 7 per cent of nitrogen, 
 dependent upon the amount of water and of foreign matter 
 which is present. The range in the water content is 
 usually from 15 to 50 per cent. Various methods have 
 been proposed for utilizing this and other nitrogenous 
 materials. 
 
 178. Wool waste as a manure. — Wool waste has long 
 been used in its natural condition as a manure for hoed 
 crops and in preparation for seeding to grass ; and, like 
 coarse stable manure, it is best to spread it broadcast 
 and turn it under with a plow. Its use is seldom to be 
 recommended, excepting where the transportation charges 
 and the cost of application are small. 
 
 179. Effect of superheated steam on wool waste. — 
 When wool waste is subjected to high steam pressure, 
 it assumes a liquid condition. Upon subsequent evapora- 
 tion there remains a dark brown powder said to be very 
 largely soluble in water and supposed to consist of leucin 
 (C 6 Hi3N0 2 ), tyrosin (C 9 HnN0 3 ), and other related amid 
 compounds. 
 
MISCELLANEOUS NITROGENOUS SUBSTANCES 105 
 
 180. Concerning Petermann's tests of availability. — 
 Experiments by Petermann, conducted in the field and in 
 pots, have appeared to show that notwithstanding that 
 the nitrogen of wool is rendered more available by the 
 process of steaming, it is still much inferior to nitrogen 
 in nitrate of soda. These experiments were made with 
 spring wheat and with beets in conjunction, in certain 
 cases, with phosphates, but without potassium salts. It 
 is interesting, in view of the omission of potash, to note 
 that the nitrogen in nitrate of soda appeared to possess 
 relatively greater superiority for the beets than for the 
 wheat. This, in the light of observations made by Hell- 
 riegel, Wilfarth and others in Germany, and by Wheeler 
 and Hartwell at the Rhode Island experiment station, 
 indicates a probable direct or indirect manurial effect of 
 the soda, the first or both of which would be expected to 
 be greater in connection with beets than with wheat. 
 Owing to this failure to provide an abundance of potash 
 and to recognize the possible beneficial alkaline effects 
 arising from the residual sodium carbonate formed from 
 the nitrate, too great value was doubtless attached to the 
 nitrogen in nitrate of soda, and too little to the effect of 
 steaming as a means of increasing the efficiency of the 
 nitrogen of the wool waste. 
 
 181. Soluble wool waste not subject to loss by leaching. 
 — It was found by Petermann that practically none of 
 the soluble nitrogenous organic matter was lost from the 
 soil by leaching, in which respect it possesses certain dis- 
 tinct advantages in open soils. 
 
 182. Benefit from steaming not equally applicable 
 to all other nitrogenous wastes. — Attention has been 
 called by S. W. Johnson to the fact that the availability 
 of certain materials, such as bones, tendons, and hide, 
 
10G FERTILIZERS 
 
 which yield glue, may be injured by steaming, incase the 
 glue is not removed. This is said to be due to the cement- 
 ing action of the glue, on account of which the decomposi- 
 tion of the material in the soil is hindered ; nevertheless, 
 horn, hoof, hair, wool, and certain other materials are 
 benefited by the treatment. 
 
 183. The production of garbage tankage. — Garbage 
 tankage is the product derived from the treatment of 
 kitchen wastes, and it may be composed of materials of 
 both vegetable and animal origin. The refuse is treated 
 with steam at high pressure, as a result of which it is 
 completely disinfected, and much of the water is expelled. 
 This product is then extracted by benzene, which is sub- 
 sequently recovered and used for the repeated extraction of 
 new lots of material. The extracted residue is then screened, 
 in order to permit of the recovery of the bones and of other 
 miscellaneous materials, in separate portions. It is said 
 by Storer that 30,000 pounds of kitchen waste have been 
 found to yield by this process 1800 pounds of grease and 
 12,000 pounds of garbage tankage. In this process the 
 vapors are condensed and passed into the sewers, and the 
 various operations are said to be practically unaccom- 
 panied by odors. 
 
 184. The fertilizer value of garbage tankage low. — 
 Such garbage tankage is of rather low value as a manure. 
 It is used by a few fertilizer manufacturers, some of 
 whom fortunately submit it to the so-called " wet cham- 
 ber " process, by which its value as a fertilizer is at least 
 somewhat improved. 
 
 It usually contains from 2.5 to 3 per cent of nitrogen, 
 1.5 to 3 per cent of phosphoric acid, and from 0.7 to 1.5 per 
 cent of potash. 
 
 185. The character of shoddy and felt refuse. — The 
 
MISCELLANEOUS NITROGENOUS SUBSTANCES 107 
 
 term "shoddy," as formerly used, referred to short frag- 
 ments of wool rejected in various woolen industries. Now, 
 however, the name is often applied to wastes of both silk 
 and wool. 
 
 186. Chemical composition of shoddy and felt. — 
 Shoddy usually contains from 4 to 12 per cent of nitrogen, 
 the average content being about 6.5 per cent. 
 
 A felt refuse examined by Goessmann was found to 
 contain "5.26 per cent of nitrogen. It may therefore be 
 classed as of about the same general character as 
 shoddy. 
 
 187. The use of felt and shoddy wastes as manures. — 
 Felt and shoddy wastes are highly esteemed as a manure 
 for grapes and certain other fruits, and especially for 
 hops. This is supposedly due to the fact that these crops 
 do not require a large amount of nitrogen at any given 
 time, but thrive best where the supply, though small, 
 is continuous throughout the season. For such pur- 
 poses shoddy is considered as one of the best substi- 
 tutes for farm-yard manure, and in many cases it is 
 even chosen in preference to the manure. From 1 to 
 2.5 tons of shoddy are considered equal to 20 tons of 
 farm-yard manure. 
 
 Shoddy not only exerts a direct manurial action, due 
 to its high content of nitrogen, but it also improves very 
 greatly the physical condition of certain soils. 
 
 188. The character of soot. — Soot consists chiefly of 
 finely divided particles of carbon which are deposited in 
 chimneys during the imperfect processes of combustion. 
 On account of its finely divided physical condition, it 
 condenses gases upon its particles to a high degree, and 
 hence often becomes rich in ammonia which it has ab- 
 sorbed from the gaseous products of combustion. 
 
108 FERTILIZERS 
 
 189. The chemical composition of soot. — The nitrogen 
 content of soot may range from about 0.5 to 6 per cent, 
 the average being about 3.2 per cent. 
 
 190. Soot benefits physically. — Owing to its dark 
 color, soot is supposed to cause soils upon which it is spread 
 to absorb more heat, thus forcing the crop and creating 
 conditions favorable to bacterial activity. When it is 
 introduced into soils it also improves their physical con- 
 dition, especially if they are of a clayey texture. 
 
 191. Soot rarely toxic. — A sample of soot has been 
 reported in Europe which was found to be toxic to plants, 
 due to the presence of pyridin or similar compounds, 
 yet the almost universal indorsement of soot as a ferti- 
 lizer shows that the presence of poisonous substances must 
 be considered as most exceptional. 
 
 192. Light soot best. — The best soot is usually that 
 which is the lightest in weight, and heavy weight indicates 
 contamination with mineral matter of questionable value. 
 The usual weight of a bushel of soot is about 28 pounds. 
 
 193. Insects and cocoons. — It has been found that 
 certain insects yield as much as 19 per cent of fat, and that 
 in their natural state they may contain from 3.2 to 8.41 
 per cent of nitrogen. In addition, the content of phos- 
 phoric acid has been found to range from 0.6 to 1.5 per 
 cent and the potash from 0.5 to 0.96 per cent. Certain 
 of the richer of these insects, after the removal of the fat 
 and complete dessication, yield a product containing as 
 much as 14 per cent of nitrogen. 
 
 The cocoons of the silk worm have been found to con- 
 tain 1.82 per cent of phosphoric acid, 1.08 per cent of 
 potash, and 9.42 per cent of nitrogen. 
 
 194. Peat and muck. — Peat and muck, though con- 
 taining all of the usual mineral elements of agricultural 
 
MISCELLANEOUS NITROGENOUS SUBSTANCES 109 
 
 importance, nevertheless contain too little of any of them 
 to be of practical significance as manures. Such vege- 
 table residues are valuable as soil amendments by virtue 
 of the large volume of organic matter which they contain, 
 and on account of their nitrogen, although the latter is 
 but very slowly available. The composition of muck and 
 peat varies widely, dependent upon whether they are 
 derived from trees, shrubs, grasses, mosses, or other forms 
 of plant life and also according to the quantities and kinds 
 of mineral matter which they contain. Air-dry peat may 
 be assumed to range in nitrogen content from 1 to 2.5 
 per cent, according to the materials of which it was formed. 
 
 195. Peat and muck especially valuable on light soils. — 
 Peat and muck are especially applicable for use on light, 
 sandy, and gravelly soils which leach badly and lack 
 vegetable matter. On such lands these materials may 
 effect a veritable transformation in productiveness, es- 
 pecially in seasons when the rainfall is light, or when it is 
 unevenly distributed, but not always if excessively dry. 
 
 196. Salt and fresh muds. — Dried mussel mud is 
 reported by Goessmann as containing 0.72 per cent of 
 nitrogen and 0.35 per cent of phosphoric acid. Another 
 sample of salt mud, with 53 per cent of water and 41 per 
 cent of ash ingredients, contained 0.4 per cent of nitrogen. 
 Fresh-water mud, with a moisture content of 40 per cent, 
 contained 1.37 per cent of nitrogen, 0.22 per cent of 
 potash, and 0.26 per cent of phosphoric acid. 
 
 None of these materials is sufficiently valuable to 
 justify hauling to a considerable distance, and they are 
 often chiefly of use in improving the physical condition of 
 sandy or gravelly soils. 
 
 197. Cereal and other seed by-products. — Among 
 the various cereal and other seed by-products, cotton- 
 
110 FERTILIZERS 
 
 seed meal is probably the most important, from the fer- 
 tilizer standpoint, of any which are extensively used in 
 the United States. Notwithstanding the high feeding 
 value of cotton-seed meal and the wisdom from the stand- 
 point of national economy of feeding it first, and of using 
 the resultant dung as a manure, enormous quantities of 
 it are used separately for special manurial purposes and 
 also as an ingredient of ready-mixed commercial ferti- 
 lizers. It is used extensively, especially in the South, not 
 only as a manure for cotton and sugar cane, but also for 
 other crops, and it is one of the favorite sources of organic 
 nitrogen, especially for tobacco. For this latter purpose 
 enormous quantities of it are used in the Connecticut 
 Valley, in the states of Connecticut and Massachusetts. 
 
 198. The composition of cotton-seed meal. — Owing 
 to changes in the method of removing the oil, cotton-seed 
 meal is not usually as rich in nitrogen as formerly, the 
 lower limit for the decorticated meal being about 6 per 
 cent, and the upper limit 7 per cent. The undecorticated 
 cotton-seed meal contains about 4 per cent of nitrogen. 
 In addition to nitrogen, cotton-seed meal contains about 
 2.5 per cent of phosphoric acid, and about 1.7 per cent of 
 potash. 
 
 199. The composition of linseed meal. — Linseed meal 
 and cake contain from 4.9 to 5.8 per cent of nitrogen, 1.2 
 per cent of potash, and 1.8 per cent of phosphoric acid. 
 
 200. The composition of malt sprouts. — Malt sprouts 
 reach a limit of from 3.5 to 4 per cent of nitrogen, 2 per 
 cent of potash, and 1.3 per cent of phosphoric acid. 
 
 201. The composition of castor pomace. — Castor 
 pomace contains from 5.5 to 5.75 per cent of nitrogen, 
 from 0.6 to 3.4 per cent of potash, and from 1.5 to 2.25 
 per cent of phosphoric acid. 
 
MISCELLANEOUS NITROGENOUS SUBSTANCES 111 
 
 202. The composition of wet brewer's grains. — Wet 
 brewer's grains contain 76 per cent or more of water, 1.2 
 per cent of ash, 0.9 per cent of nitrogen, 0.5 per cent of 
 phosphoric acid, and 0.05 per cent of potash. 
 
 203. The composition of gluten feed. — Gluten feed 
 contains usually from 4 to 5 per cent of nitrogen, but only 
 0.75 per cent of ash. 
 
 204. The utilization of the spent wash of distilleries. — 
 The spent wash of distilleries of various kinds contains 
 notable quantities of nitrogen. This represents a loss of 
 1 to 1.25 pounds of nitrogen, per 10 gallons of 100 per cent 
 alcohol produced. The wastes from the distillation of 
 beet sugar, molasses, and sucrate liquors contains 1.4 
 per cent of nitrogen and 0.9 per cent of salts. Attempts 
 to recover these wastes by dry distillation are complicated 
 by the tars and other products, difficult of purification. 
 Many other methods of treating these liquors have like- 
 wise been tested. 
 
 205. The process of Vasseux. — The process of Vas- 
 seux, which is employed with gratifying results in France 
 and Spain, consists in concentrating the wash and adding 
 sulfuric acid, whereupon the potassium sulfate crystal- 
 lizes out in the mass and is separated by decantation, 
 filtration, and centrifugal treatment, yielding finally a 
 product containing 75 to 80 per cent of potassium sulfate. 
 The drying of the liquor is completed in vacuo, where- 
 upon it is poured into trucks. After cooling, this residue 
 is crushed and prepared for agricultural use. The final 
 product contains 6 to 7 per cent of nitrogen and 6 to 7 
 per cent of potash. It is almost wholly soluble in 
 water, and is said to be an excellent fertilizer. The 
 usual yield is 300 pounds of fertilizer per tori of the 
 molasses treated. 
 
112 FERTILIZERS 
 
 206. The process of Effront. — A process devised by 
 Effront consists in converting the organic nitrogen of 
 these spent liquors into ammonia by the employment of 
 amidase in an alkaline medium. The ferment is then 
 separated for further use, and the ammonia is won by dis- 
 tillation. A butyric acid ferment and others separated 
 from a garden soil have been similarly employed by 
 Effront in treating spent wash. By this method there was 
 secured from 814 gallons of molasses, not only the cus- 
 tomary 22 gallons of alcohol, but also 77 pounds of pure 
 volatile fatty acids. 
 
CHAPTER XI 
 
 THE AVAILABILITY OF ORGANIC NITROGEN AND FACTORS 
 AFFECTING IT 
 
 In determining the availability of organic nitrogenous 
 substances, the efficiency of their nitrogen is usually com- 
 pared with that in nitrate of soda, which for the sake of 
 convenience is usually placed at 100. 
 
 207. The factors of temperature and moisture. In 
 such work temperature and moisture conditions, as well 
 as the texture and chemical reaction of the soil, are im- 
 portant factors, for it is well recognized that in warm 
 climates, especially on open soils, and for plants having a 
 long period of growth, comparatively inert forms of nitro- 
 gen act much better than in temperate climates and on 
 compact soils. 
 
 208. Effect on the soil reaction. — It is coming to be 
 more generally appreciated than formerly that soils are 
 rendered less acidic or more alkaline by sodium nitrate, 
 whereas certain organic nitrogenous substances may exert 
 an appreciable ultimate acidic effect upon the soil by 
 virtue of the nitric acid resulting in the course of their de- 
 composition. 
 
 209. Effect of large applications at the outset. In 
 case a very heavy application of nitrate of soda is made 
 at the outset, it may in some cases interfere, for a time, 
 with the physiological functions of the plant to such an 
 extent that even if it actually takes up more nitrogen, 
 
 T 113 
 
114 FERTILIZERS 
 
 the total quantity of dry matter may finally be less than 
 that produced by a like amount of nitrogen in certain 
 organic materials, which are more slowly available. For 
 this reason deductions as to the availability of the nitro- 
 gen should properly be based upon the nitrogen actually 
 taken up by the plants, rather than merely upon the total 
 dry matter produced. 
 
 210. Employment of different amounts of nitrogen. — 
 It is also important in making such availability tests to 
 use two or three series of experiments in which different 
 amounts of nitrogen are employed. 
 
 211. Other elements must be supplied generously. — 
 Care should also be taken to determine definitely by 
 experiment whether enough of all the other fertilizing 
 ingredients has been employed to insure that nitrogen 
 is really made the factor which limits growth. The 
 point just mentioned is especially important in view of 
 the now well-recognized physiological and other func- 
 tions, performed by sodium salts when potash is lacking, 
 for if the supply of potash were insufficient, the greater 
 yield produced by nitrate of soda, in comparison with 
 organic nitrogen, might be due to a considerable extent 
 to the soda having performed some part of some of the 
 functions of potash. If this were not guarded against 
 or anticipated, the conclusion might be drawn that the 
 nitrogen in other materials was relatively much more in- 
 ferior in comparison with that in nitrate of soda than the 
 actual facts would justify. 
 
 212. False conclusions a result of neglect of con- 
 ditions. — A careful study of the literature of the subject 
 reveals cases in which comparisons of nitrogenous sub- 
 stances have been made in which no potassic fertilizers 
 whatever were employed, nor was evidence sought to 
 
THE AVAILABILITY OF ORGANIC NITROGEN 115 
 
 show that sufficient was already present in the soil to 
 meet the maximum plant requirements. To this and to 
 similar oversights may be attributed some part of cer- 
 tain of the discrepancies concerning especially the value 
 of hoof meal and horn meal, although they may also have 
 been due to the different methods of preparing the ma- 
 terials used by the different experimenters ; and to the 
 occasional unrecognized adulteration with substances of 
 highly inferior character. 
 
 213. Results by Eckenbrecher. — A study of the effi- 
 ciency of certain organic substances was made by Ecken- 
 brecher, for a single season, in " sterile " sand from which, 
 based upon nitrate of soda at 100, he classified the effi- 
 ciency of the nitrogen in certain substances as follows : — 
 
 Bone meal 
 Horn meal 
 Dried blood 
 Crude guano 
 
 Fob the Production 
 of Straw 
 
 100 
 91 
 
 86 
 6 
 
 For the Production 
 of Grain 
 
 77 
 
 56 
 
 65 
 
 6 
 
 It is evident that very different results might have been 
 secured in normal soil. 
 
 214. Results by Kellner. — It was found by Kellner, 
 in the warm climate of certain parts of Japan, that organic 
 nitrogen was superior to nitrogen in sulfate of ammonia, 
 due, presumably, to the rapid nitrification of the former, 
 and to its loss by drainage before the plants could utilize it. 
 
 215. Results by Petermann. — Many experiments on 
 the availability of organic nitrogen were made by A. Peter- 
 mann in Belgium from which he concluded that nitrate 
 
116 FERTILIZERS 
 
 of soda should be given the highest rank. This was fol- 
 lowed in efficiency by dried blood, then by wool which 
 had been treated with sulfuric acid, next by bone meal, 
 then by untreated wool, and finally by leather meal. 
 
 216. Precautions suggested by Wagner and Dorsch. — 
 Extended studies of availability by Wagner and Dorsch 1 
 led them to lay down the following rules for such tests : 
 (1) The experiments must cover several successive years. 
 The same lots of soil must also be used throughout the 
 whole period, and the same fertilization must be repeated 
 annually. This is to aid in arriving at any cumulative 
 effect of the organic fertilizers, in contrast to the supposed 
 more temporary action of the nitrogen in nitrates. Con- 
 cerning this recommendation, it may be said that its im- 
 portance seems to have been somewhat overestimated in 
 view of the many cases on record in which but relatively 
 little effect is noticed, the second year, from heavy appli- 
 cations of organic nitrogen ; furthermore, the cumulative 
 effect of nitrate of soda in an acid soil, due to its basic 
 properties and to the possibility of its nitrogen being partly 
 transformed into " humous " combinations, may also be 
 much greater than is sometimes recognized. 
 
 (2) The soil must contain sufficient lime to insure that 
 there will be neither delay nor cessation of the process of 
 nitrification. 
 
 (3) In selecting the soil, one should neither use one that 
 is extremely favorable as concerns its physical character, 
 nor one which is exceedingly poor, but rather a soil that 
 would be ranked as medium in this respect. Later, if 
 desired, the results may be studied under extreme con- 
 ditions. 
 
 J Die Stickstoffdungung der Landwirtschaftlichen Kulturpflanzen, 
 Erster Theil, Berlin, 1892, pp. 242-258. 
 
THE AVAILABILITY OF ORGANIC NITROGEN 117 
 
 (4) One should introduce as many different organic ni- 
 trogenous fertilizers into the experiment as possible, in order 
 that the results with a given substance may appear in their 
 proper relation to those secured with other substances. 
 
 12 3 4 5 
 
 Fig. 8. — Barley, "Unlimed." 
 1. No nitrogen. 2. Ammonium sulfate. 3. Leather. 
 
 4. Dried blood. 5. Nitrate of soda. Same amounts of pot- 
 ash, phosphoric acid, and nitrogen used in each case. Same 
 as Fig. 9, except for the omission of lime. 
 
 (5) None of the fertilizers should be applied until spring, 
 in order to avoid possible loss during the winter. 
 
 (6) In case a substance contains some other fertilizer 
 ingredients than nitrogen, care must be taken, by the addi- 
 tion of an assured excess of all of them, to eliminate the 
 possibility of their having influenced the result. 
 
118 
 
 FERTILIZERS 
 
 (7) All of the lots of soil must receive even slightly 
 more of all the necessary fertilizers, other than nitrogen, 
 than are necessary to the production of a maximum crop. 
 
 (8) Less nitrogen should be used in all cases than is 
 necessary to the production of a maximum crop, in order 
 that the best forms may exert their full effect. 
 
 (9) In order to make sure that the conditions under (7) 
 and (8) have been surely met, nitrogen must be applied 
 in at least two different amounts. 
 
 12 3 4 5 6 
 
 Fig. 9. — Barley, "Limed" (except 1). 
 
 1. No nitrogen, no lime. 2. No nitrogen. 3. Ammonium sulfate. 
 4. Leather. 5. Dried blood. 6. Nitrate of soda. All received like 
 amounts of potash, phosphoric acid, and nitrogen. Like Fig. 8, excepting 
 that lime was used for all but No. 1. 
 
 (10) The nitrogen content of the soil which is selected 
 should be so low that fairly large applications of nitrogen 
 may be made, for the accuracy of the results will be in- 
 creased thereby. 
 
 (11) One should use relatively larger amounts of the 
 less available substances than of the more active ones, in 
 order that the experimental error may be made as nearly 
 alike in all cases as possible. 
 
 (12) The experiments should be conducted on land 
 
THE AVAILABILITY OF ORGANIC NITROGEN 119 
 
 in its natural condition, as well as in pots ; since the former 
 provides against any possible errors due to higher tem- 
 peratures in the pots, and the use of the latter insures 
 against losses by drainage. 
 
 217 Results of tests by Wagner and Dorsch. — Ine 
 experiments by Wagner and Dorsch were conducted with 
 due recognition of the foregoing precautions, including 
 tests in pots and in soil in its natural location. These 
 experimenters call attention to the variation in the 
 chemical and physical character of such nitrogenous 
 materials from time to time; also to the wide variations 
 in soil temperature, moisture content, and other factors 
 that may modify results. Finally, as representative 
 average figures expressive of the efficiency of the nitrogen 
 in various materials, based upon nitrate of soda at 100, 
 they give the following : — 
 
 Relative Value 
 
 Nitrogen in nitrate of soda „„ 
 
 Nitrogen in sulfate of ammonia •••;•/; 
 Nitrogen in dried blood, horn meal, and green (not 
 
 yet woody) plant substance • •"• 
 
 Nitrogen in fine ground bone meal, meat meal (azo- 
 
 tin), and dry ground fish Jj" 
 
 Nitrogen in stable manure ^ 
 
 Nitrogen in wool waste j*" 
 
 Nitrogen in leather meal 
 
 218. Results by Wheeler and Hartwell. — In experi- 
 ments by Wheeler and Hartwell made in " Miami " silt 
 loam, in deep pots set in the ground so as to make the 
 interior and exterior soil level, sulfate of ammonia was 
 found to be highly toxic, if employed without lime, but 
 when used with lime its efficiency rose to 92 on the basis 
 of 100 for the nitrogen in nitrate of soda. Similarly, on 
 the unlimed soil the efficiency of the nitrogen in dried 
 blood was but 45.5 on the same basis, whereas after liming 
 
120 FERTILIZERS 
 
 it was 90.3. Steamed, ground leather had an efficiency 
 on the unlimed soil of but 0.9 ; but after liming the effi- 
 ciency rose to 13.8, or to essentially the same figure noted 
 by Wagner in many of his individual experiments. 
 
 219. Results by Voorhees. — In a series of experi- 
 ments by Voorhees at the New Jersey experiment station 
 it was found that the nitrogen of nitrate of soda was more 
 available than that in any other materials. It was also 
 found, when nitrate of soda was employed, that the crop 
 was able to secure even a larger proportion of the soluble 
 nitrogen derived from the soil and from the manures which 
 had been added to it, than when no nitrate was used. 
 Placing the value of the nitrogen in nitrate of soda at 100, 
 the following seasonal variations in the efficiency of the 
 nitrogen in other substances were observed by Voorhees : 
 the value of the sulfate of ammonia was 99.5 in the year 
 1898, 77.9 in 1899, and 87.8 in 1900. The corresponding 
 values found for dried blood in the three years were, respec- 
 tively, 95.4, 61.3, and 73.1. 
 
 It was also shown by Voorhees that the soluble nitrogen 
 in liquid manure possesses a high value. The insoluble 
 nitrogen in fresh and leached barn-yard manures was 
 found to become gradually soluble ; and its value was much 
 greater as the length of the period of growth was in- 
 creased. 
 
 Views of Lawes. — In the climate of England, Lawes 
 considered the nitrogen of shoddy and of most other or- 
 ganic substances as being only from one-half to two-thirds 
 as efficient as that in nitrate of soda, sulfate of ammonia, 
 and guano. 
 
 220. Results by Kellner on wet soil. — It has been 
 shown by Kellner that in the wet rice fields of Japan am- 
 monia, instead of nitrates, is formed from organic nitrog- 
 
THE AVAILABILITY OF ORGANIC NITROGEN 121 
 
 enous substances. In his experiments with rice he used 
 in one series twice as much nitrogen as in the other, and in 
 both cases liberal quantities of phosphoric acid and potash. 
 The applications were also made some days in advance of 
 the setting of the rice plants in order to avoid toxic effects 
 from a too rapid formation of ammonia at the outset. 
 The natural soil, when air-dried, contained 0.61 per cent 
 of nitrogen. Under such circumstances, in the warm 
 climate which prevailed, the relative efficiency of the vari- 
 ous materials, based upon the mean of the gain in crop, and 
 of the nitrogen recovered, was found to be as follows : — 
 
 Relative Efficiency 
 
 No manure 
 
 Sulfate of ammonia 100 
 
 Bone meal, steamed 142 
 
 Fish-scrap, 9.9 per cent of nitrogen 135 
 
 Fish-scrap, 9.5 per cent of nitrogen 133 
 
 Blood meal 130 
 
 Bone meal, raw 120 
 
 Distillery slop, dried 118 
 
 Horn meal • 116 
 
 Peruvian guano 116 
 
 Press cake 104 
 
 Rape cake 106 
 
 Night soil 106 
 
 Farm manure 88 
 
 Rice husks 48 
 
 Green plants 42 
 
 Owing to the fact that irrigation waters were used on 
 the lands where the foregoing tests were made, the mate- 
 rials containing nitrogen which was wholly or partly sol- 
 uble were at a great disadvantage, as compared with the 
 materials from which the nitrogen could not be so readily 
 dissolved and carried away. This applies particularly 
 to the sulfate of ammonia, farm-yard manure, night soil, 
 guano, and materials of similar character. It is obvious, 
 therefore, that the figures in the preceding table are ap- 
 
122 FERTILIZERS 
 
 plicable only to similar conditions and not to those usually 
 existent on farm lands. 
 
 221. Results by Seyffert. — In experiments by Seyf- 
 fert with kohl-rabi, in which identical amounts of nitrogen 
 were used in all cases, in the various materials, the fol- 
 lowing results were secured : — 
 
 Grams of Crop 
 
 No nitrogenous fertilizer 76 
 
 Crude Mejillones guano 71 
 
 Leather meal, steamed 469 
 
 Steamed bone meal 1572 
 
 Dried blood 1654 
 
 Horn meal, steamed 2005 
 
 Nitrate of soda 2608 
 
 222. Results by Heinrich. — Experiments are on record 
 by Heinrich in which he found, with oats, that there was 
 no material difference in the efficiency of the nitrogen in 
 leather meal and in blood meal. This result is, however, 
 so completely out of accord with the experience of other 
 experimenters that serious doubt is cast upon the genuine- 
 ness of the blood meal, or upon the suitableness of the con- 
 ditions under which the experiment was conducted, or 
 possibly upon the interpretation of the experimental 
 data. 
 
 223. Results by Johnson. — According to S. W. John- 
 son's experiments with Indian corn, certain organic nitrog- 
 enous fertilizers should be rated in efficiency as follows : — 
 
 Nitrate of soda 100 
 
 Castor pomace (best results) 85 
 
 Linseed meal 80 
 
 Dried blood 77 - 
 
 Cotton-seed meal 76 
 
 Castor pomace (poorest results) 74 
 
 Hoof and horn meal 72 
 
 Dried fish 70 
 
 Tankage 68 
 
THE AVAILABILITY OF ORGANIC NITROGEN 123 
 
 224. Results by the nitrification method of Muntz and 
 Girard. — Experiments were made by A. Muntz and 
 Girard to determine the relative value of nitrogenous 
 fertilizers by subjecting them to nitrification and measur- 
 ing the amount of nitrates produced at the end of 30 and 
 39 days. This resulted in showing that the nitrogen in 
 sulfate of ammonia should be ranked ahead of that in 
 organic compounds. This was followed in order by the 
 nitrogen of guano, bat manure, leguminous plants used as 
 green manure, dried blood, meat meal, horn meal, and 
 roasted horn. Roasted leather was found to nitrify very 
 slowly, and raw leather not to any practical extent. 
 
 225. The pepsin method. — Many investigators in the 
 United States and in Europe have studied the solvent 
 action of pepsin solution upon various organic nitrogenous 
 substances as a means of determining their crop-producing 
 value. The results in many cases accord fairly well with 
 those secured in tests with plants, though certain gross 
 disagreements have been noted. It was found in the 
 course of this work that a preliminary treatment of the 
 material with borax increased the solvent action of the 
 pepsin. 
 
 226. The permanganate method. — In the hope of 
 finding some more reliable chemical method than that 
 afforded by treatment with pepsin, many experiments with 
 potassium permanganate have been made in acid, neutral, 
 and alkaline solutions. Recently the agricultural experi- 
 ment stations of New England, New York, and New 
 Jersey have adopted, tentatively, the treatment with an 
 alkaline solution of potassium permanganate, for the pur- 
 pose of furnishing evidence as to the probable efficiency of 
 the insoluble organic nitrogen in ready-mixed commercial 
 fertilizers. The organic residues, remaining after extract- 
 
124 FERTILIZERS 
 
 ing the fertilizers with water, are being tested, by way of 
 pot experiments with plants, in order to ascertain how 
 far this chemical method of treatment is in accord with 
 the degree of availability shown by plants in normal soil. 
 227. Lipman's ammonification method. — Recently 
 Lipman l and others have suggested the determination of 
 the availability of organic nitrogen by the rate at which 
 ammonification occurs, under definite conditions. Ac- 
 cording to Lipman, the results by this method agree suffi- 
 ciently well with those secured in vegetation experiments 
 with plants, to justify its employment in many cases. 
 Attention is called to the fact that the rate of ammoni- 
 fication is affected by the carbohydrate content of the 
 soil and by other factors. 
 
 1 Centralb. f. Bakt., 31 (1911), 49-85. 
 
CHAPTER XII 
 
 CALCIUM AND POTASSIUM NITRATES 
 
 Calcium nitrate and potassium nitrate are two espe- 
 cially useful sources of nitrogen which will be considered 
 in detail. 
 
 228. Calcium nitrate a new fertilizer. — Calcium ni- 
 trate is a comparatively new product in so far as concerns 
 its production and use for agricultural purposes, and it is 
 but just being introduced into this country in an experi- 
 mental way, though it has been used to some extent in 
 Europe for a very short time. This nitrate has been long 
 and favorably known as one of the important compounds 
 formed in soils in connection with the usual processes of 
 nitrification. 
 
 229. Production possible due to cheap electricity. — 
 Recently, due to the great developments in the line of 
 cheapening the cost of electricity, it has become possible, 
 by employing an electric arc furnace, to oxidize the nitro- 
 gen of the air to nitrous oxid and nitric oxid. In fact, in 
 1898 Sir William Crookes predicted that the world's supply 
 of nitrogen would soon come from the air. He pointed 
 out that all that was needed was some means of maintain- 
 ing the energy necessary to cause the continuous union 
 of oxygen and nitrogen on a sufficiently large scale. Based 
 upon the work of Lord Raleigh, he further expressed the 
 belief that with the perfection of the electrical plant at 
 Niagara Falls this would be accomplished. 
 
 125 
 
120 FERTILIZERS 
 
 230. The work of Lovejoy and Bradley. — Soon there- 
 after Lovejoy and Bradley, by producing several arcs 
 between platinum poles with a continuous current of 10,000 
 volts, generated oxicl of nitrogen which was converted 
 into a mixture of sodium nitrite and sodium nitrate. This 
 process proved, however, too destructive to the apparatus 
 to be remunerative. 
 
 231. The process of Birkeland and Eyde. — The later 
 process developed successfully by Birkeland and Eyde 
 involves the use of an alternating current of not more than 
 about 5000 volts. An arc is formed between U-shaped 
 copper electrodes cooled from within by a current of water. 
 The arrangement of the two hollow electrodes is such as 
 to produce a flat and broad flame, the temperature of which, 
 though only 2600° C, is not so luminous as might be 
 expected. The flaming electrical arc is moved backward 
 and forward by a magnet in such a way as to produce a 
 maximum of contact and consequent oxidation. About 
 2694 cubic feet of air are passed through the furnace, 
 per minute, where it is subjected to an alternating current 
 of from 3000 to 4000 volts, giving a flame 6 feet in 
 diameter. When the air emerges, its temperature is from 
 600° to 700° C. It then carries about 1 per cent of nitric 
 oxid and is next passed through a steam boiler in order 
 that it may give up a part of its heat, in the generation 
 of steam. The current is then passed through two oxidiz- 
 ing chambers. Here it takes on oxygen from the air, 
 after which it is passed through five condensing towers, 
 each of which is about 50 feet high. In the meantime, 
 water is allowed to trickle down the broken quartz with 
 which four of the towers are filled ; and by the time it has 
 reached the bottom of the fourth, it contains approxi- 
 mately 5 per cent of nitric acid. This solution is then passed 
 
CALCIUM AND POTASSIUM NITRATES 127 
 
 down the third, second, and first towers successively, and, 
 upon reaching the bottom of the last of these, it contains 
 50 per cent of nitric acid. From here it passes to a fifth 
 tower, which contains milk of lime, and, finally, to a sixth 
 tower, which carries beds of lime. In this last tower the 
 solution is absorbed, and there is formed a mixture of 
 calcium nitrite and of calcium nitrate. This product 
 upon treatment with some of the nitric acid is all changed 
 into nitrate, and the nitrous fumes which result are led 
 back to the oxidizing chamber. The final product, after 
 concentration, is poured, in a molten condition, into can- 
 isters for shipment. 
 
 232. First product too hygroscopic. — The crystallized 
 nitrate of lime which was produced at first was so hy- 
 groscopic that it would melt if held in the hand, and it 
 became necessary to mix it with peat dust before its ap- 
 plication to the soil. 
 
 233. Processes for lessening hygroscopic tendency. 
 Later attempts have been made to make a basic nitrate 
 of lime, but this contained only 11.7 per cent of nitrogen, 
 and hence increased to a serious extent the cost of trans- 
 portation per unit of nitrogen. Subsequently a partially 
 dehydrated salt was produced containing 13 per cent of 
 nitrogen. 
 
 In order to obviate the tendency of nitrate of lime to 
 deliquesce, it has been mixed at times with alkaline sul- 
 fates, with sulfate of potash, sulfate of magnesia, and with 
 calcined kieserite. By such treatment a powder is formed 
 which is said to afford no more difficulty, in this particular 
 respect, than is met with in the handling of nitrate of soda. 
 
 234. Chemical composition. — The solidified or pow- 
 dered product of calcium nitrate contains about 25 per cent 
 of lime in an unchanged condition. It also contains 13 
 
128 FERTILIZERS 
 
 per cent of nitrogen, which is equivalent to 75 per cent of 
 calcium nitrate. 
 
 235. Calcium nitrate as a fertilizer. — The chief draw- 
 back to the practical use of calcium nitrate as a fertilizer 
 has been its tendency to deliquesce readily, especially in 
 a moist climate. 
 
 Since calcium nitrate carries an excess of lime, it is an 
 ideal source of nitrogen for certain of the granitic, gneissic, 
 slate, shale, and sandstone soils, many of which are often 
 practically devoid of carbonate of lime ; but on calcareous 
 soils, and for plants that do not respond favorably to lim- 
 ing, it may be much less valuable. The tendency of cal- 
 cium nitrate is the direct opposite of that of sulfate of 
 ammonia, for the latter rapidly exhausts the calcium car- 
 bonate supply of the soil. In actual practice the results 
 secured with calcium nitrate appear to lack more or less 
 in agreement. This is doubtless due to the fact that suffi- 
 cient attention has not always been paid to the quite dif- 
 ferent character of the soils under experiment, and to the 
 widely varying effect of lime upon the growth of the differ- 
 ent varieties of plants, for which it has been used. In 
 general, however, the results from the use of calcium ni- 
 trate have been highly favorable, agreeing well with those 
 secured with nitrate of soda. 
 
 236. Danger of the earlier products injuring horses 
 and workmen. — Attempts to sow calcium nitrate broad- 
 cast by itself are said to be likely to result in serious injury 
 to the hands and eyes of the workmen. If one attempts 
 to use a machine, such as is ordinarily employed for dis- 
 tributing fertilizers, it flows too freely to admit of its uni- 
 form and satisfactory distribution. On this account it 
 has been suggested that the material be mixed with soil or 
 with some other suitable dry substances before its dis- 
 
CALCIUM AND POTASSIUM NITRATES 129 
 
 tribution. It has been used mixed with calcium cyanamid 
 with better results than when the cyanamid is used alone. 
 
 237. Extent of the output of calcium nitrate. — In the 
 first three months of 1908 the output of the Norwegian 
 Hydro-electric Nitrogen Works of Christiana was 1059 
 tons of calcium nitrate ; or more than in the entire previ- 
 ous year. Since that time other plants have also begun 
 operations. In April, 1911, it was reported that the total 
 available output until August of that year was already 
 sold ; and that, with the completion of the new works then 
 under construction, it was expected that the annual pro- 
 duction would reach 100,000 tons. 
 
 238. Cost of producing calcium nitrate. — The present 
 price of calcium nitrate is based upon that of nitrogen in 
 nitrate of soda, on which basis it can be produced at a good 
 profit. In fact, it has been claimed that with the present 
 cheap electric current, generated in Norway, calcium ni- 
 trate can be manufactured at a price 30 per cent cheaper, 
 per unit of nitrogen, than the present ruling price of nitro- 
 gen in nitrate of soda. 
 
 239. Other processes. — Other modified processes for 
 the manufacture of calcium nitrate have been devised by 
 E. Rossi, in Italy, and by G. Erlwein, who is in the em- 
 ploy of the firm of Siemens & Halske, in Germany. 
 
 240. Sources of potassium nitrate. — Impure potassium 
 nitrate, known commercially as " niter " or " saltpeter," 
 is found naturally in certain parts of India, also near 
 Mabelstadt and Peliska in Cape Colony, South Africa, 
 and in other countries, where it appears as a white incrus- 
 tation on the surface of the soil. It is also often found 
 mixed with the soil to a considerable depth. 
 
 The nitrate is extracted from the earthy matter by 
 water. The solution is then evaporated by exposure to 
 
130 FERTILIZERS 
 
 the rays of the sun, or by artificial heating, after which it 
 is allowed to stand and crystallize. In this crude or par- 
 tially purified condition it is known as " grough," and it 
 usually contains about 44 per cent of potassium oxid and 
 11 per cent of nitrogen. There is frequently associated 
 with the potassium nitrate from 1 to 10 per cent of im- 
 purities, chief among which are sodium chlorid and sul- 
 fates of soda, potash, and lime. 
 
 241. Artificial niter beds. — Potassium nitrate has also 
 been prepared at times in artificial niter heaps or beds. 
 Such heaps are prepared under a shelter, where there is an 
 impervious floor to prevent the escape of liquids. The 
 side of the heap most exposed to evaporation is often kept 
 vertical, whereas the other side is built up in the shape of 
 successive grooved terraces upon which the drainage from 
 stables is occasionally conducted. In this way the fer- 
 mentation of the vegetable and animal matter, which is 
 mixed with limestone, old mortar, wood-ashes, or similar 
 basic material, is readily promoted. The nitrates which 
 are formed are finally leached to the vertical side of the 
 heap, where they accumulate as an efflorescence, due to the 
 continual evaporation at that point. When the accumu- 
 lation has become great enough to justify it, the outside 
 vertical layer and the nitrate accumulated on its face are 
 removed. The material is next extracted with water and 
 is still further purified by crystallization. The residual 
 matter, after its extraction, is returned to the terraces on 
 the rear of the heap. Usually the heaps are torn up and 
 rebuilt after from two to three years. 
 
 A temperature of from 60° to 70° F. is considered favor- 
 able to the nitrifying processes, though, as is well known, the 
 optimum temperature for nitrification is probably about 
 98° F, 
 
CALCIUM AND POTASSIUM NITRATES 131 
 
 There was long much mystery about the cause and the 
 nature of the changes actually taking place in such beds, 
 but this has been removed by the work of Frankland, 
 Warrington, Winograclsky, and others, who have shown 
 that the changes are the result of the activity of certain 
 species of microorganisms. 
 
 The chief nitrates associated with the potassium nitrate 
 from such artificial beds are nitrates of lime, magnesia, 
 and ammonia. These may all be converted into potas- 
 sium nitrate, however, by treatment with potassium 
 carbonate. 
 
 242. Made for industrial purposes from nitrate of soda. 
 — For industrial purposes, potassium nitrate is manufac- 
 tured from the Chilian nitrate of soda and potassium 
 chlorid. 
 
 243. Potassium nitrate often economical for agricul- 
 tural use. — It is usually asserted that, potassium nitrate, 
 on account of its high price, finds little or no application 
 in agriculture, excepting in a small way in certain special 
 garden fertilizers, and that the elements which it fur- 
 nishes can be secured more cheaply in nitrate of soda and 
 in muriate of potash. Nevertheless, it has often happened 
 in recent years in the United States that niter has been the 
 most economical source of potash and nitrogen on the 
 Atlantic seaboard, and at points where the transportation 
 charges on fertilizers are still greater, it may frequently 
 be found economical for agricultural uses. 
 
 244. Chlorin avoided by using potassium nitrate. — 
 Potassium nitrate is especially applicable wherever large 
 amounts of chlorin are objectionable; as, for example, for 
 tobacco, sugar beets, and for certain other field crops, 
 but more particularly in greenhouses, where toxic residues 
 should be especially avoided. 
 
CHAPTER XIII 
 
 NITRATE OF SODA 
 
 The most widely used and known of all nitrate fertilizers 
 is nitrate of soda, which, owing to its vast agricultural im- 
 portance, will be discussed in its various relationships to 
 plants and soils. 
 
 245. Sources of nitrate of soda. — Quantities of nitrate 
 of soda of economic importance occur in Egypt, and minor 
 deposits also in the pampas of Peru, Chili, and Bolivia. 
 The chief deposits in the world are found in the plateau of 
 Tarapaca in northern Chili (formerly Peruvian territory), 
 and in the desert of Atacama. This plateau, which is 
 merely an elevated sea bed, is now from three to four 
 thousand feet above the level of the ocean. It extends 
 for approximately seventy-five miles north and south, and 
 from twenty to twenty-five miles from east to west. The 
 plateau where the nitrate is most abundant is shut in by the 
 Cordilleras on the east and by a low range of foothills on 
 the west. Rain seldom falls there more frequently than 
 every two to three years, and then in such small quanti- 
 ties that it evaporates quickly. Immediately on the sur- 
 face of this plateau is found a rock known as " costra," 
 carrying occasionally small amounts of phosphates, but 
 consisting chiefly of sand and gypsum. Beneath this lies 
 the " congels," a conglomerate rock composed of gravel 
 and clay. Underneath the whole lies the " caliche " or 
 impure nitrate of soda associated with earthy matter and 
 
 132 
 
NITRATE OF SODA 133 
 
 with salts of calcium, magnesium, and potassium. The 
 overlying rocks range usually from three to ten feet or 
 more in depth, while the caliche may vary in depth from a 
 few inches to from 8 to 10 feet. Its average depth is 
 about 3 feet. 
 
 246. Concerning the origin of the Chilian nitrate of 
 soda. — Several theories have been advanced to explain 
 the mode of origin of the nitrate. (1) It has been suggested 
 that the nitrates have resulted from natural electrical 
 discharges by which the nitrogen of the air has been fixed, 
 resulting in the final formation of nitrates. The sugges- 
 tion has also been made that the carbonates of the alkalies 
 and of the alkaline earths have aided in the oxidation of 
 the atmospheric nitrogen. 
 
 (2) That the nitrate was formed from guano deposits, 
 which upon nitrification yielded calcium nitrate. The 
 calcium nitrate is believed to have then reacted with 
 sodium chlorid and with other sodium salts of some in- 
 land salt lake by a process of change analogous to one 
 said to be taking place at the present time in Hungary. 
 By the reactions suggested, sodium nitrate is supposed 
 to have been produced. The resulting calcium chlorid is 
 believed to have been largely removed in solution. This 
 view of the origin of the beds is supported also in some 
 measure by the presence of sodium chlorid in the caliche. 
 The lack of considerable amounts of phosphate, associated 
 with the deposit, is, however, considered as an objection to 
 this theory. 
 
 (3) That in the elevation of the plain from the bed of 
 the ocean great numbers of marine animals and vast quan- 
 tities of the great sea-weeds, which are common on the 
 Pacific coast of North and South America, were raised to 
 a position where their decomposition and ultimate nitri- 
 
134 FERTILIZERS 
 
 fication took place readily. The small amounts of phos- 
 phates in the overlying rocks have been considered as 
 supporting evidence of this origin, and likewise also the 
 presence of iodates in the caliche. It is inconceivable, 
 however, that the volume of sea-weed could have been 
 sufficient to supply all of the vast quantity of nitro- 
 gen ; and, furthermore, the absence of bromin, which is 
 a constituent of sea-weeds, is a serious blow to this 
 theory. 
 
 (4) It is more probable for many reasons that the ni- 
 trates had their origin in the higher mountain ranges, per- 
 haps chiefly at a much earlier time when the rainfall was 
 more abundant, and that the evaporation of these saline 
 waters, due to progressive desiccation, gave rise to the 
 present deposits. It remains, however, to be explained 
 by this theory, from what source the iodin was derived. 
 This idea of the origin of the nitrates is upheld by A. D. 
 Hall, whereas another recent English writer adheres to the 
 idea of their having been formed from sea-weeds. 
 
 Recent investigations by Headden and Sackett 1 as to 
 the cause of the excessive accumulations of nitrates, which 
 are found to be highly destructive to apple orchards and 
 to some farm crops in certain sections of Colorado, have 
 shown that nitrogen is fixed from the air in great quantities, 
 chiefly by Azotobacter chroococcum. The extent of fixa- 
 tion in a sample of soil from the Colorado college farm, in 
 the course of a period of incubation extending over 27 
 days, is said to have been equal to 5222 pounds of nitrogen, 
 or to 17.5 tons of " proteids " per acre-foot of soil, per 
 annum. If the rate of increase of nitrate nitrogen ob- 
 served by Headden, for a period of 48 days, were main- 
 
 1 Buls. 178 and 179, respectively, Agr. Expt. Sta., Colorado Agricul- 
 tural College. 
 
NITRATE OF SODA 135 
 
 tained continuously for a year, it would amount to four 
 and one-third tons of nitrates per acre-foot of soil. In a 
 later article 1 Headden states that " The area in which the 
 nitrogen fixation by the Azotobacter is actually taking place 
 in Colorado under our semi-arid conditions is sufficiently 
 extensive to entitle the suggestion, that the nitrogen pres- 
 ent in the Chili-saltpeter was also fixed by Azotobacter, to 
 serious consideration." Hilgard also calls attention to the 
 great quantities of nitrates in certain of the soils of Cali- 
 fornia; and in one locality, over an area of ten acres, 
 they were found at the rate of 1200 pounds per acre, the 
 maximum being two tons per acre. 
 
 (5) It has been pointed out recently by Kuntze that the 
 vicunas and llamas are now known to have roamed in 
 immense numbers, probably since time immemorial, over 
 that part of the Andes where the nitrate deposits occur, 
 and the fact that they always deposit their dung in the 
 same place points to such accumulations as a possible 
 source of the nitrates. The common salt is accounted for, 
 according to this theory, as coming from the urine and 
 excrement, and from the alkaline salts resulting from rock 
 decomposition. This theory does not, however, account 
 for the iodin which has long been one of the chief supports 
 of the sea-weed theory of the origin of the nitrate. 
 
 It appears quite possible that two or three of these dif- 
 ferent sources may have contributed to the deposits. 
 
 247. The first exploitation of the nitrate of soda. — 
 Notwithstanding that the existence of the nitrate fields 
 had been known since a much earlier date, the first ship- 
 ments of nitrate of soda were not made from Iquique 
 until 1830. These amounted to 800 tons. In the next 
 ten years the annual output had risen to 10,000 tons, and 
 
 1 Proceedings of the Colorado Scientific Society, 10 (1911), 120. 
 
136 FERTILIZERS 
 
 in 1907 it amounted to 1,660,000 tons, and it has since been 
 rapidly increasing. 
 
 248. Chemical composition and purification of the 
 nitrate of soda. — The crude caliche contains only from 17 
 to 60 per cent of nitrate of soda. The native material is 
 removed from its beds by the use of dynamite. It is then 
 freed from the associated earthy matter by dissolving in 
 hot water, after which it is allowed to crystallize out in 
 tanks. The crystals are then removed, dried, and bagged 
 ready for shipment. The mother liquors are subsequently 
 utilized for the recovery of iodin compounds and certain 
 other valuable salts. In its commercial state, nitrate of 
 soda contains from 95 to 97 per cent of nitrate, or from 
 15 to 16 per cent of nitrogen, which is equivalent to 18 
 to 19 per cent of ammonia. Pure nitrate of soda contains 
 16.47 per cent of nitrogen, equivalent to 20 per cent of 
 ammonia, but this is too costly for agricultural uses. 
 
 249. Impurities in nitrate of soda. — The impurities 
 present in the commercial nitrate of soda employed for 
 agricultural purposes are 2 to 3 per cent of water, 0.5 to 
 1.5 per cent of sodium chlorid, small amounts of sodium 
 sulfate, potassium sulfate, and calcium sulfate ; also so- 
 dium iodate and traces of other less important salts. Some- 
 times even potassium nitrate may occur as an impurity in 
 nitrate of soda, though it is usually very largely removed 
 in the mother liquors. The only impurity that is trouble- 
 some agriculturally is sodium perchlorate, which has some- 
 times been found in quantities equal to from 6 to 7 per 
 cent. Amounts in excess of 1 per cent have been found to 
 be harmful to crops, causing, in the case of cereals, a pe- 
 culiar twisting of the leaves and poor development of the 
 stalk which does not occur under normal conditions. In 
 recent years, due doubtless to greater precautions in the 
 
NITRATE OF SODA 137 
 
 course of the purification, few, if any, complaints of injury 
 due to the presence of perchlorate have been heard. 
 
 It is only in the rarest instances that adulteration of 
 nitrate of soda has been met with, a fact doubtless due to 
 vigilant inspection, and to the ease with which foreign 
 materials can be recognized by chemical and other means. 
 
 250. Physical characteristics of nitrate of soda. — The 
 color of the commercial nitrate of soda ranges from brown 
 and pink to grayish white. It becomes lumpy as a result 
 of storage, and for this reason it is often reground when 
 sold for the home-mixing of fertilizers. It is important 
 to store nitrate of soda in a reasonably dry location, or it 
 will readily liquefy to some extent by the absorption of 
 water from the air. 
 
 251. The availability of nitrate of soda as plant food. — 
 Nitrate of soda ranks with potassium nitrate and calcium 
 nitrate as one of the most efficient of all nitrogenous fer- 
 tilizers, for it can be utilized by plants at once without 
 the necessity of undergoing preparatory fermentative 
 changes. 
 
 252. Quantities to apply and care in using. — Nitrate 
 of soda is applied in quantities ranging usually from 100 
 to 400 pounds per acre, though as high as 600 to 800 pounds 
 are sometimes employed for special purposes. 
 
 Great care must be taken, in top-dressing spring grains, 
 grass fields, and lawns, to apply the nitrate of soda when the 
 grass is dry, for otherwise the tips of the leaves may be 
 severely burned. Bags of the material should not be left 
 standing on moist lawns or meadows, or the grass under- 
 neath will be likely to be killed. Owing to its destructive 
 power, particular attention must be paid to keeping nitrate 
 of soda away from immediate contact with the seed. 
 
 In connection with spring top-dressing, it is important 
 
138 
 
 FERTILIZERS 
 
NITRATE OF SODA 139 
 
 to bear in mind that if nitrate of soda is applied early, it 
 tends to promote tillering and hence increases the number 
 of stalks of grass and of cereals, sometimes, in the latter 
 case, even at the expense of the yield of grain. If, on the 
 contrary, the application is delayed until the tillering is 
 complete, it merely aids in the development of the stalks 
 already in existence. It is usually desirable to top-dress 
 grass at an early date in the spring, not only to promote 
 tillering, but also in order to push the growth as much as 
 possible while abundant water is still present in the soil. 
 
 253. Nitrate of soda corrects soil acidity. — It is a well- 
 established fact that the use of nitrate of soda may gradu- 
 ally improve the condition of certain acid soils which are 
 naturally deficient in carbonate of lime, whereas sulfate 
 of ammonia may render their condition far worse. This 
 fact was strikingly demonstrated at the Rhode Island 
 experiment station in the years from 1891 to 1900. Later 
 also a similar result followed the use of a mixture of am- 
 monium sulfate and ammonium chlorid, by Voelcker, at 
 Woburn, England. In fact, in 1881 Adolf Mayer, 1 in 
 classifying various agricultural chemicals, referred to 
 nitrate of soda as being " physiologically basic." This 
 was on account of the fact that the acid is utilized by plants 
 to a greater extent than the sodium, in consequence of 
 which the latter is transformed, in the soil, into sodium 
 carbonate. 
 
 254. Physical effects of the residue from nitrate of 
 soda. — The residual sodium carbonate from nitrate of 
 soda may result injuriously or beneficially, according to 
 the character of the soil. It is well known, for example, 
 that on heavy clay soils, especially if deficient in vegetable 
 matter, the continued employment of nitrate of soda may 
 
 x Landw. Vcrs.-Sta., 26, 94, 95. 
 
140 FERTILIZERS 
 
 give rise to so much sodium carbonate as to seriously 
 deflocculate the clay, by which its tendency to bake is 
 enormously increased. The ability of such soils to admit 
 air, and to absorb and deliver water to the plant in proper 
 amounts, is also greatly impaired thereby. In such cases 
 liming has not always been found to be an effective rem- 
 edy, and it has been recommended to use acidic fertilizers, 
 such as acid phosphate, sulfate of ammonia, and muriate 
 of potash, which are said to correct the condition satis- 
 factorily. 
 
 255. The residual soda may liberate potash. — Atten- 
 tion has been called by Hall and others to the action of the 
 soda of the nitrate of soda as a liberator of potash in soils, 
 whereby the arising of potash deficiencies may be delayed 
 for several seasons. 
 
 256. Residual soda can replace potash in part. — 
 Several years ago, also, Paul Wagner in Germany and 
 Atterberg in Sweden called attention to the fact that soda 
 could probably replace potash to a certain extent, in which 
 case it might be expected to act as a conserver of the 
 potash supply in the soil. This idea is also supported by 
 experiments at the Rhode Island agricultural experiment 
 station. In one instance sodium carbonate, as well as 
 sodium chlorid, more than doubled a crop of mangel 
 wurzels when as much as 330 pounds per acre of muriate 
 of potash, or its equivalent of potassium carbonate, had 
 been added in the fertilizer. In the case of certain other 
 crops which do not take up large amounts of soda under 
 any circumstances, the benefit from using extra sodium 
 salts was small, and yet further applications of potassium 
 salts were beneficial. It was evident, therefore, that the 
 soda in some cases had been chiefly helpful in some other 
 way than as a liberator of potash. 
 
NITBATE OF SODA 141 
 
 The idea that soda is able to perform certain functions, 
 or at least a part of certain functions, in plants, which 
 would be performed by potash if a sufficient supply of 
 the latter were available, was also observed at the same 
 station. This was shown by water-culture experiments 
 in which the possibility of indirect manurial action, through 
 the liberation of potash, was not only eliminated, but also 
 any effect of increased osmotic pressure, and of other 
 factors which might possibly exert an influence upon 
 plant growth. 
 
 257. The soda of nitrate of soda may in certain cases 
 conserve the soil potash. — Many analytical data secured 
 in Rhode Island with field crops, grown by the use of 
 varying amounts of sodium and potassium salts, showed 
 that at least certain of the " root " crops may take up far 
 more soda and potash than seem strictly essential to bring 
 about a given crop yield. If soda is absent, this over- 
 loading of the plant with alkali is at the expense of the 
 potash supply of the soil. If soda is used in the fertilizers; 
 this " hunger " for alkali is partially satisfied with soda, 
 and the potash supply of the soil is consequently con- 
 served for future crops. It seems probable that some 
 writers have paid too little attention to this feature. They 
 have consequently attributed the indirect effect of the 
 nitrate of soda too largely to liberation of potash from 
 zeolitic combinations in the soil. 
 
 258. Soil improvement by using nitrate of soda. — A 
 striking instance of soil improvement as a result of the use 
 of nitrate of soda is afforded at the Rhode Island experi- 
 ment station, where it has been used continuously from 
 1893 to 1912. At the outset the soil was so deficient in 
 carbonate of lime that only an occasional clover plant 
 could withstand the existing conditions. The lack of 
 
142 FERTILIZERS 
 
 available basic substances was in fact so great that a 
 single moderate application of sulfate of ammonia, on a 
 neighboring plot of land, proved immediately toxic. Not- 
 withstanding this, by the long-continued use of nitrate 
 of soda, even without the aid of lime, the productiveness * 
 of the soil for most agricultural plants has shown marked 
 improvement, and the successful cultivation of clover 
 on the land has been rendered more nearly possible. 
 In fact, the present conditions are but little, if at all, in- 
 ferior, for most varieties of plants, to those where sulfate 
 of ammonia has replaced the annual applications of nitrate 
 of soda and where several heavy applications of lime have 
 been made in the period of nineteen years. It is evident, 
 therefore, that nitrate of soda has a decided basic effect ; 
 and on an acid soil, of a physical character not readily 
 injured by deflocculation, it may readily bring about 
 long-enduring and marked improvement in crops. 
 
 259. Nitrate of soda may injure certain soils. — It 
 must be obvious that in arid or semi-arid regions where 
 the soil is sufficiently basic, or is already unduly so, nitrate 
 of soda, if used continuously, might soon magnify the con- 
 dition to a limit of danger, especially to all of those crops 
 which are highly sensitive to basic conditions. 
 
 From what has preceded it is evident that no general 
 rule for the use of nitrate of soda can be formulated which 
 is applicable to all classes of soils, for one must take into 
 account their physical and chemical character as well as 
 the peculiar adaptations of the individual plants to be 
 grown. 
 
 260. Benefit not due solely to hygroscopic effects. — 
 It appears probable that much of the benefit from the 
 use of nitrate of soda, which was formerly attributed to 
 its increasing the hygroscopic character of the soil, may 
 
NITRATE OF SODA 143 
 
 have been due to certain of the beneficial effects which 
 have just been discussed, but which were formerly un- 
 recognized or but little understood. 
 
 261. The soda as a carrier of phosphoric acid into 
 plants. — It has been found at the Rhode Island experi- 
 ment station that the use of common salt or sodium car- 
 bonate in fertilizers tends to an increase in the phosphorus 
 content of certain root crops ; and since sodium carbonate 
 is formed in the soil in consequence of the employment of 
 nitrate of soda, the use of the nitrate must eventually 
 result in the same effect. Such benefit is, however, not 
 confined to root crops, for in experiments with cereals 
 Wagner and Dorsch x find support for the experiments by 
 Emmerling, Loges, Beseler, and Maercker, to the effect 
 that by the use of nitrate of soda there resulted a larger 
 yield, with more economical utilization of both phosphoric 
 acid and potash, than when nitrate was not employed. 
 
 262. Nitrate of soda conserves the lime supply of the 
 soil. — In the examination of drainage waters at the 
 Rothamsted experiment station it was found, in the case 
 of some of the plots in Broadbalk field, that the applica- 
 tion of nitrate of soda had lessened the annual loss of 
 carbonate of lime by from 200 to 300 pounds per annum. 
 
 263, Nitrate of soda not a stimulant. — Nitrate of 
 soda is often referred to as a plant stimulant, or, in other 
 words, according to the definition of one of the leading 
 authorities, as something "Producing increased vital 
 action in the organism at any of its parts." The term 
 "stimulant" should, however, preferably be applied to that 
 which acts in the manner described, but which does not 
 enter into and form an essential part of the organism itself, 
 and which is normally foreign to it. It is obvious that 
 
 » Die Stickstoffdiingung der Landw. Kulturpflanzen, Berlin, 1892. 
 
144 FERTILIZERS 
 
 nitrate of soda is not a stimulant in this latter sense, and 
 that all of the elements absolutely essential to plant 
 growth might with equal propriety be called stimulants. 
 For example, a plant reared in a medium free from iron 
 soon becomes chlorotic, but recovers almost immediately 
 upon its application to the nutrient medium. In fact, 
 the recovery is essentially as quick as that of plants when 
 supplied with nitrates, in cases where available nitrogen 
 is greatly needed. It is indeed a misfortune, because of 
 the quick action of certain fertilizers, that the term "stimu- 
 lant" should ever have been applied to them, for they ac- 
 tually yield to the plant essential elements of plant food. 
 As concerns the public, the designation of certain plant 
 food ingredients as stimulants tends to create an unwar- 
 ranted prejudice against them, and the farmer is falsely 
 led to believe that, following their first beneficial effect, 
 conditions unfavorable to his crop are likely to arise. 
 
 Much of the former prejudice against nitrates, on the 
 ground that they are stimulants, has doubtless arisen 
 from observing the frequent temporary benefit from their 
 use when unaccompanied by the other ingredients of 
 plant food. It ought to be plainly evident, however, if a 
 soil is but sparingly provided with available potash and 
 phosphoric acid, that liberal applications of nitrates will 
 cause these other soil ingredients to become exhausted 
 much sooner than otherwise. In such cases the nitrates 
 have not acted as stimulants, but have merely furnished 
 the missing ingredient required in the manufacture by 
 the plant of the readily available potash and phosphoric 
 acid of the soil, into the finished crop product. It must 
 be obvious that these materials cannot be utilized in the 
 building of plants and still remain in the soil for the benefit 
 of crops which follow. 
 
NITRATE OF SODA 145 
 
 264. Nitrate of soda yields quick returns on the manurial 
 investment. — The old idea that the more the effect of a 
 fertilizer can be prolonged in the soil, the more economical 
 it is, must give way to the idea that the quicker the returns 
 on the money invested in the fertilizers, the greater are 
 likely to be the net profits. It is, however, important to 
 recognize that there may sometimes be cases in which a 
 given investment in a large quantity of a very cheap, slowly 
 acting fertilizer may be more remunerative than the pur- 
 chase for the same sum of money of a small amount of 
 one which acts quickly. In such cases the price per ton, 
 the amount of plant food contained therein, the danger of 
 loss or of unfavorable transformations resulting in the soil, 
 and the length of time before it will be possible for the 
 plants to make use of it, must all be given due considera- 
 tion. When so considered, nitrate of soda will not be looked 
 upon as a " stimulant " or as something to be avoided, but 
 as an excellent fertilizer. Nevertheless, nitrate of soda is 
 a fertilizer which must be used with good judgment. 
 One must consider not only the length of the period of 
 growth of the plants concerned, but also their special 
 characteristics and requirements. Attention must also 
 be paid to the character of the soil as concerns the possi- 
 bilities of loss by drainage ; and to the effect of the nitrate 
 of soda upon the soil texture and its chemical reaction. 
 
 265. Possible effects of nitrate of soda on the micro- 
 organisms of the soil. — To what has preceded may be 
 added the possible consideration of the effect of the nitrates 
 upon the microscopic plant and animal life of the soil, 
 since a disturbance of the numerical relation of certain of 
 these two forms and even of the different microscopic 
 plants (including bacteria) may have a marked influence 
 upon the productivity of the soil. 
 
146 FERTILIZERS 
 
 266. Ammonium nitrate. — At present ammonium ni- 
 trate (NH4NO3) is rarely used for agricultural purposes 
 because of its high cost ; yet it is a most excellent ferti- 
 lizer, especially where it is desirable to employ a source of 
 nitrogen which will leave in the soil no objectionable 
 residues. Such conditions are most frequently met with 
 in greenhouses, where, owing to the great value of the 
 product from a small area, its use may often be permissible. 
 Ammonium nitrate contains 35 per cent of nitrogen, one 
 part existing in ammoniacal and the other in nitrate form. 
 This material possesses one very distinct advantage over 
 all of the usual nitrogenous fertilizers, for the reason that 
 the cost of transporting a unit of nitrogen is very low. 
 This is on account of its concentrated character and the 
 fact that it does not contain some occasionally useless or 
 low-priced ingredient such as soda or lime. 
 
 267. The synthetic production of ammonia and am- 
 monium salts. — Experiments are now being conducted 
 which have shown the possibility of the synthetic produc- 
 tion of ammonia by the compression of hydrogen and 
 nitrogen at high temperatures in the presence of uranium 
 oxid, pure iron, and of other catalyzers. If this process 
 can be placed on an economic basis, as is claimed, the 
 manufacture of ammonia and of nitric acid may yet be 
 made so cheap that ammonium nitrate can be generally 
 used as a fertilizer. An important feature of this process 
 is that the union of the gases does not depend upon power- 
 ful electric currents. On this account great water 
 power is not vital to success, and the manufacture can 
 therefore be carried on practically anywhere. 
 
CHAPTER XIV 
 
 AMMONIUM SALTS AND CALCIUM CYANAMID 
 
 The ammonium salt of the greater agricultural impor- 
 tance at present is ammonium sulfate. This is derived 
 chiefly from the destructive distillation of coal in coke 
 ovens, blast furnaces, gas works, and elsewhere. 1 
 
 268. The manufacture of ammonium sulfate. — It is 
 asserted that the first attempt to recover the ammonia in 
 connection with the manufacture of coke was made by 
 Stauf in 1764, but the first satisfactory plant for this pur- 
 pose was not erected until 1858, when one was established 
 at St. Denis. 
 
 The amount of nitrogen in coal ranges from 1.5 to 2 
 per cent, and of this only about 15 per cent is transformed 
 into ammonia and recovered in the water used for washing 
 the gas. The ammonia is redistilled from this water, 
 collected in sulfuric acid, and the resulting sulfate of 
 ammonia is won by crystallization. It yields a white, 
 yellowish, or gray salt containing about 20.5 per cent of 
 nitrogen. The appearance of the yellow, gray, or occa- 
 sional blue or brown color may be due to traces of tarry 
 products, ferrocyanid, formed from cyanids which are 
 usually present, and to materials sometimes accompany- 
 ing thiocyanates. 
 
 269. Thiocyanates a former toxic impurity of ammo- 
 nium sulfate. — The presence of thiocyanates is readily 
 
 1 For the details of this process, see The Manufacture of Chemical 
 Manures, by Fritsch, London, 1911. 
 
 147 
 
148 FERTILIZERS 
 
 recognized by the reddish coloration produced when ferric 
 chlorid is added to a watery solution of sulfate of am- 
 monia. Its occurrence in quantities sufficient to be deadly 
 to vegetation has been noted in sulfate of ammonia sold 
 in Europe ; but because it is so easily recognized, and the 
 importance of its avoidance is now so well understood, 
 it is seldom encountered. It was present a few years 
 ago in a lot of sulfate of ammonia sold in Rhode Island, 
 but the quantity was found by experiment insufficient to 
 prove positively toxic to the usual farm crops. 
 
 270. Chemical composition of sulfate of ammonia. — 
 When pure, sulfate of ammonia contains 21.2 per cent of 
 nitrogen. The commercial product is usually sold under 
 a guaranty of 20.2 per cent of nitrogen or 24.5 per cent of 
 ammonia. 
 
 271. Sulfate of ammonia must not be mixed with 
 alkaline substances. — Owing to the ease with which 
 ammonia is liberated by alkalies, sulfate of ammonia 
 should never be mixed, before its application, with wood- 
 ashes, potassium carbonate, slaked or burned lime, basic 
 slag meal, or other materials of similar basic character. 
 Considerable losses have been said to result after the 
 application of sulfate of ammonia to a rich garden soil 
 that had been liberally limed. Similar losses also occur 
 from light calcareous soils in times of drought. Ordi- 
 narily, however, there is but little loss of ammonia by 
 volatilization when sulfate of ammonia is applied to soils 
 as a fertilizer, under the usual conditions and in the usual 
 amounts. Indeed, there is much evidence to this effect, 
 even in the case of soils which have been adequately, 
 though not excessively, limed. 
 
 272. Absorption of sulfate of ammonia by soils. — 
 The ammonia of ammonium salts is usually readily ab- 
 
AMMONIUM SALTS AND CALCIUM CYANAMID 149 
 
 sorbed by soils, in such a way that it is less subject than 
 nitrates to immediate losses by leaching. This is prob- 
 ably due to the fact that the ammonia enters at once 
 into chemical combinations with certain organic salts, 
 formed by the reactions of lime and magnesia with prod- 
 ucts of decaying vegetable matter, and also with zeolites 
 and possibly other similar compounds of the soil. The 
 sulfuric acid of the sulfate of ammonia unites with the 
 bases which are replaced by ammonia. The ammonia, 
 in these combinations which result in the soil, nevertheless 
 yields readily to nitrification. 
 
 273. The use of sulfate of ammonia exhausts soils of 
 lime. — It was long supposed that most of the ammonia 
 thus retained by soils was transformed at once and held 
 as ammonium carbonate, the compound which results 
 from the reaction of ammonium sulfate with calcium 
 carbonate, as follows : — 
 
 (NH 4 ) 2 S0 4 + CaC0 3 = (NH 4 ) 2 C0 3 + CaS0 4 • Aq. 
 
 ammonium calcium ammonium calcium 
 
 sulfate carbonate carbonate sulfate 
 
 By this reaction calcium sulfate (land plaster or gypsum) 
 is formed, which in time is largely lost by its solution and 
 passage into the drainage waters, whereby the soils grad- 
 ually become deficient in lime. Furthermore, by the 
 later nitrification of that portion of the ammonia which 
 is not changed to carbonate at the outset, the nitric 
 acid which is formed unites with further quantities of 
 lime and magnesia, whereby the soil becomes still more 
 depleted of its available carbonates, and hence tends to 
 develop acidic conditions. 
 
 274. Nitrogen of sulfate of ammonia fixed by micro- 
 organisms. — Nitrogen in ammonia, like that in nitrate 
 
150 FERTILIZERS 
 
 of soda, is subject to more or less fixation by its being 
 taken up by, and becoming a part of the organized struc- 
 ture of, the bacteria, fungi, and other minute plant and 
 animal denizens of the soil. 
 
 275. The efficiency of sulfate of ammonia as a fertilizer. 
 — It was concluded by Wagner and Dorsch and has been 
 well substantiated by other experimenters that, as a 
 general rule, nitrogen in sulfate of ammonia possesses 
 about nine-tenths the efficiency of nitrogen in nitrate of 
 soda. The difference of one-tenth may be attributed in 
 part to possible small losses of ammonia by volatilization, 
 but chiefly to the transformation of some of the nitrogen 
 into organic forms, such, for example, as the structure of 
 the organisms which effect its transformation into nitrates. 
 Such a generalization as to the relative efficiency of sul- 
 fate of ammonia is nevertheless capable of only restricted 
 application, for with other plants than the cereals, which 
 have been commonly used in such experiments, somewhat 
 different conclusions might be drawn. This is especially 
 true if no account is taken of the possible physiological 
 functions of the soda, especially where the potash supply 
 is deficient. This is plainly shown by a study of a tabu- 
 lation by Stutzer 1 of a large number of European ex- 
 periments with nitrate of soda and sulfate of ammonia 
 in which, as far as concerned the cereals, nitrate of soda 
 sometimes gave even poorer results than the sulfate of 
 ammonia. With mangel wurzels and sugar beets, how- 
 ever, the results were almost invariably much in favor of 
 the nitrate of soda. This, as explained elsewhere, may 
 have been due to a correction of the chemical reaction of 
 the soil by the soda of the nitrate of soda, to a conserva- 
 tion of the available potash supply by virtue of soda being 
 
 1 Der Chilisalpeter, Berlin. 
 
AMMONIUM SALTS AND CALCIUM CYAN AMID 151 
 
 taken up in its stead, by the soda having been of benefit 
 to the plants physiologically, or in still other ways. 
 
 276. Soda important in trials of nitrate of soda and 
 sulfate of ammonia. — All of the points which have been 
 mentioned emphasize the importance of taking soda into 
 account in comparing the efficiency of the nitrogen in 
 these compounds. A precaution which may be taken is 
 to add to the pots or plots of land which receive the sulfate 
 of ammonia as much sodium carbonate as would be formed 
 from the nitrate of soda. If this precaution is not taken, 
 it becomes doubly imperative to determine by check tests 
 if enough potash is actually present to fully meet the alkali 
 requirements of the plants under experiment. The need 
 of considering the possible effect upon the soil reaction 
 which may be exerted by the residual sodium carbonate 
 derived from the nitrate of soda will obviously be deter- 
 mined very largely by the character of the soil at the outset, 
 and by the adaptations of the plants employed in the ex- 
 periments. 
 
 277. Double decompositions follow the use of ammo- 
 nium salts. — In the course of the Rothamsted experi- 
 ments it was found that when ammonium chlorid and 
 ammonium sulfate were applied to the land, chlorin and 
 sulfuric acid began to appear almost at once in the 
 drainage waters, combined with the lime and magnesia 
 which the ammonia had replaced in the soil. As has been 
 explained in another connection, the nitric acid formed in 
 soils as a result of the nitrification of the ammonia may 
 combine with lime, magnesia, or even with potash and 
 soda. 
 
 On account of the acid, in combination, in the sulfate 
 of ammonia at the outset, the drain on the lime and mag- 
 nesia of the soil arising from the use of sulfate of ammonia. 
 
152 FERTILIZERS 
 
 is far greater than that created by the employment of 
 dried blood and other sources of organic nitrogen, which, 
 when nitrified, leave but one acid to be neutralized by the 
 soil bases. Incidentally this tendency to the develop- 
 ment of soil acidity by the use of organic nitrogenous 
 materials, just as is eventually the case by the use of sul- 
 fate of ammonia, does not appear to have been sufficiently 
 appreciated, and it is usually entirely overlooked. 
 
 278. Partial soil sterility sometimes caused by sulfate 
 of ammonia. — Many cases of marked inferiority of sul- 
 fate of ammonia as a source of nitrogen had long been on 
 record, but the reason for the very inferior results had not 
 been carefully studied until it was taken up apparently 
 coincidently by Wagner and Dorsch in Germany and at 
 the Rhode Island experiment station. In the year 1890 
 it was observed at the latter station that sulfate of am- 
 monia was highly toxic, even the first season of its applica- 
 tion. At other points in the state of Rhode Island it 
 either became quickly toxic or gave evidence of a tendency 
 in that direction. The experiments of the succeeding 
 three years proved conclusively that this toxic action was 
 due to the creation of an acidic condition of the soil which, 
 either directly or by virtue of toxic substances to which 
 it gave rise, was highly destructive to many varieties of 
 agricultural plants. It was also shown that this condition 
 could be corrected by sodium carbonate, potassium car- 
 bonate, caustic magnesia, carbonate of lime, slaked lime, 
 calcium oxalate, and calcium acetate, but that when these 
 bases were combined with chlorin or sulfuric acid, they 
 were usually of no practical value as correctives of the 
 condition. Toward the close of the same decade the 
 experiments by Voelcker at Woburn, England, in which 
 an occasional inferiority of action of the ammonium salts 
 
AMMONIUM SALTS AND CALCIUM CYANAMID 153 
 
 had already been observed, gave evidence of a highly 
 toxic effect upon barley. This was shown later to have 
 been due apparently to the development of soil acidity, 
 and to be capable of correction by liming. 
 
 279. The conditions caused in acid soils by sulfate of 
 ammonia not fatal to all plants. — In the course of the 
 earlier experiments with sulfate of ammonia, at the Rhode 
 Island experiment station, it was found that conditions 
 were produced thereby which were prohibitive of the 
 
 Fig. 11. — Limed Grasses. 
 Timothy at left, redtop at right. Sulfate of 
 ammonia. Compare with Fig. 12. 
 
 successful growth of lettuce, spinach, beets, Swiss chard, 
 cress, kohl-rabi, cabbage, cauliflower, asparagus, canta- 
 loupes, clover, alfalfa, string beans, peas, vetch, Kentucky 
 blue-grass, timothy, and many other plants. Neverthe- 
 less, these conditions failed to interfere with the successful 
 growth of the blackberry, Norway spruce, watermelon, 
 common sorrel, cranberry, and other plants. In fact, sev- 
 eral of these latter plants seemed to thrive best of all 
 under conditions which were exceedingly toxic to plants 
 of other kinds. In 1909, after having made sixteen sue- 
 
154 
 
 FERTILIZERS 
 
 cessive annual applications of sulfate of ammonia, and 
 after the soil had become still more toxic to most plants, 
 than in the earlier years, it was found that the conditions 
 for the growth of the flowering perennial, Silene orientalis, 
 were better than where lime had been used and where, 
 by its application, the conditions formerly toxic to most 
 plants had again been made highly favorable. This 
 emphasizes the fact that any discussion of toxic substances 
 
 in the soil must 
 embrace a consid- 
 eration of the par- 
 ticular variety of 
 plant involved. 
 
 The observa- 
 tions at Woburn 
 with a mixture of 
 ammonium chlo- 
 rid and of am- 
 monium sulfate 
 agree with those 
 made in Rhode 
 Island, with am- 
 monium sulfate, 
 in showing that 
 barley is more sensitive than wheat to the toxic condi- 
 tions produced. This difference has been attributed by 
 Hall to the deeper rooting habit of the wheat than of 
 the barley, and to a more robust constitution of the 
 wheat plant. Many of the observations made in Rhode 
 Island, in the course of which several hundred different 
 varieties of plants have been tested, fail to support the 
 idea that the different depth of the roots of plants is the 
 chief, or, in some cases, even an important, determining 
 
 Fig. 12. — Unlimed Grasses. 
 Timothy at left, redtop at right. Sulfate of 
 ammonia. Compare with Fig. 1 1 and note how 
 soil acidity has lessened the proportion of tim- 
 othy. 
 
AMMONIUM SALTS AND CALCIUM CYANAMID 155 
 
 factor. The results indicate that the explanation of these 
 differences in plants must often be sought in quite other 
 directions. In fact, in the course of the Rhode Island 
 experiments the mangel wurzel, which Hall, in comparison 
 with barley, calls a " deep rooting " plant, was subject to 
 injury in a far greater degree than barley, when sulfate of 
 
 Fig. 13. — Effect of Treatment on Common Sorrel. 
 Dried blood, sulfate of ammonia, and nitrate of soda, respectively, 
 from left to right. Fertilized alike with potash and phosphoric acid. 
 The more acid the soil was made, the better the growth. Nitrate of 
 soda lessens acidity. 
 
 ammonia was used without lime. This difference in the 
 two kinds of plants was not only true of soils where sulfate 
 of ammonia had been applied previously, but also of those 
 poor in lime in many different parts of Rhode Island, and 
 even when nitrate of soda was the only artificial source of 
 nitrogen employed. 
 
 280. Sulfate of ammonia an aid in rendering certain 
 grasses dominant. — In connection with the permanent 
 
156 • FERTILIZERS 
 
 grass experiments at Rothamsted, it was found that the 
 use of ammonium salts (ammonium chlorid and ammo- 
 nium sulfate) made the presence of sweet vernal grass 
 (Anthoxanihum odoratum L.) and sheep's fescue (Festuca 
 ovina L.) prominent, — a fact attributed to the holding of 
 the ammonia in the surface soil and to the shallow rooting 
 habit of these grasses. It has been found, however, at 
 the Rhode Island experiment station that an acidic ferti- 
 lizer, of which sulfate of ammonia was one constitutent, 
 when used successively upon certain grass plats, has driven 
 out Kentucky blue-grass, clover, and certain other grasses 
 and weeds, leaving red fescue (Festuca rubra L.) and 
 sheep's fescue in practically undisputed possession of the 
 land. Where, on the contrary, basic fertilizers have been 
 used, in which the sulfate of ammonia is replaced by nitrate 
 of soda, and acid phosphate by basic slag meal, Kentucky 
 blue-grass, white clover, and other grasses and weeds have 
 almost obscured the fescues. It is also true that these 
 fescues have become dominant on old meadows where 
 natural acidic soil conditions, due to lack of carbonate of 
 lime, inhibit the growth of many other species of grass. 
 It may therefore be questioned whether the shallow root- 
 ing is the sole or even dominant factor in the survival of 
 these grasses, and if the chemical reaction of the soil, 
 special ability to utilize ammonia or even unnitrified nitrog- 
 enous substances, and resistance to soil compounds which 
 are toxic to other plants, may not be equally important 
 factors. 
 
 281. Sulfate of ammonia may cause the suspension of 
 certain bacterial activity. — Sulfate of ammonia, if used 
 to the extent of creating highly acidic conditions in the 
 soil, causes the suspension, at least to a great extent, of the 
 normal bacterial life and gives rise to the growth of molds, 
 
AMMONIUM SALTS AND CALCIUM CYANAMID 157 
 
 fungi, and doubtless to special types of bacteria suited 
 to the unusual conditions. It was found, for example, 
 in connection with the permanent grass experiments at 
 Rothamsted, that where sulfate of ammonia had long been 
 used, nitrification had practically ceased ; and the grass 
 plants were therefore supposedly forced to utilize ammonia 
 or combined nitrogen, instead of nitrates. 
 
 The Rothamsted experiments show that barley ripens, 
 and mangel wurzels cease their growth, earlier, when 
 manured with ammonium salts than when grown with 
 the aid of nitrate of soda. This has been explained at 
 Rothamsted as due to the greater descent of the nitrates 
 into the soil and hence to a deeper rooting habit of the 
 plants, induced thereby, especially in dry seasons, on 
 which account the plants are better supplied with water. 
 The Rothamsted experiments show, nevertheless, that 
 in such dry seasons sulfate of ammonia acts relatively 
 better than in wet ones, due supposedly to higher soil 
 temperatures, to better aeration, and hence to a better 
 chance for nitrification. On this account, in moderately 
 dry seasons, the ammonia would be expected to nitrify 
 rapidly, and when so nitrified it is as movable in the soil 
 as the original nitrate ; hence the preceding explanation 
 would not seem to be adequate in all cases. In fact, it 
 seems probable, in view of the possible lack of potash and 
 of the now well-established plant food value of soda under 
 such circumstances, especially for mangel wurzels, that 
 the soda itself may have been a factor in keeping up the 
 longer growth and also in causing the usually greater crop. 
 
 Experiments by Maercker, and by Wagner and Dorsch, 
 show that barley is relatively more responsive than the 
 other cereals to nitrate of soda. Wagner also observed 
 that barley is dependent, to a far greater degree than oats, 
 
158 FERTILIZERS 
 
 upon potash manuring. On account of this fact, he ex- 
 plains that the better action of nitrate of soda than of 
 sulfate of ammonia, upon barley, is due to the fact that 
 the soda comes more into play by way of performing a part 
 of the functions of potash. 
 
 282. Sulfate of ammonia liberates plant food. — Ac- 
 cording to the accepted idea that the ammonia of sulfate 
 of ammonia can replace lime, magnesia, potash, and soda, 
 when the latter are held in zeolitic combinations in the 
 soil, it is evident that the use of sulfate of ammonia is 
 likely to result in the liberation of these plant food ingre- 
 dients ; and if employed in excess without other fertilizers, 
 it may finally result in seriously impoverishing the soil. 
 This fact is fully substantiated by the studies of drainage 
 waters made by Voelcker and by Lawes and Gilbert. 
 The compounds which were chiefly increased in the drain- 
 age waters, upon the application of ammonium salts, 
 were chlorids, sulfates, and calcium nitrate. It was 
 found that 400 pounds of sulfate of ammonia removed 
 from the soil annually in this way about 172 pounds 
 of lime. 
 
 283. Ammonium salts fleeting in their effects. — Not- 
 withstanding that ammonia enters readily into zeolitic 
 and other chemical combinations in the soil, it is not ca- 
 pable of being continuously held for successive years. 
 This is shown by experiments at Rothamsted in which 
 mineral fertilizers were alternated through a long series 
 of years with ammonium salts ; for in the alternate years 
 when only mineral fertilizers were applied, the yield aver- 
 aged about the same as where the same mineral fertilizers 
 were used continuously without any ammonium salts. 
 These results further support the fact of the rapid trans- 
 formation of the ammonia into nitrates in the soil. They 
 
AMMONIUM SALTS AND CALCIUM CYAN AMID 159 
 
 also show that the same care must be exercised in the em- 
 ployment of the ammonium salts as in the application of 
 nitrates, in order that no more may be applied than will 
 be utilized in the same season. 
 
 It was found by Voelcker, Frankland, and others that 
 the larger the application of ammonium salts in the spring, 
 the greater were the losses of nitrates in the drainage water 
 the following December. The loss which resulted in this 
 way was found to amount to 8.5 pounds of nitrogen per 
 acre for each inch of rainfall lost by leaching. After an 
 autumn application of ammonium salts at the rate of 600 
 pounds per acre, Frankland found the loss of nitrogen 
 equal to 18 pounds per acre for each inch of rainfall lost 
 by percolation. 
 
 284. Ammonium salts leach less quickly than nitrates. 
 — Even if the employment of considerable amounts of 
 ammonium salts in the autumn has been found to be un- 
 economical, it is nevertheless true that in making spring 
 applications the danger of immediate losses by leaching 
 are less, in the case of ammonium salts, than in connec- 
 tion with nitrates. 
 
 285. Ammonium sulfate may cause injury on light 
 calcareous soils. — It was observed by Deherain at 
 Grignon, France, that on light calcareous soils an efflor- 
 escence of calcium sulfate followed applications of ammo- 
 nium sulfate, after a few days of drought. The physical 
 condition of the soil was so seriously injured in conse- 
 quence, that the ill effects of drought were much height- 
 ened, and, furthermore, the injury lasted for several sea- 
 sons. On soil of the same character, nitrate of soda was 
 nevertheless highly beneficial. 
 
 For several reasons Deherain has recommended the 
 restriction of applications of ammonium salts to stiff or 
 
160 FERTILIZERS 
 
 heavy land, and even then to quantities ranging from 140 
 to 175 pounds per acre. 
 
 286. Ammonia may injure plants. — It appears to be 
 well established that sufficient ammonia may enter the 
 plant to exert a granulating or coagulating effect upon 
 the protoplasm, a result which is inimical to plant life. 
 Nevertheless, Hosaus, Adolf Mayer, and others have found 
 small amounts of ammonia present in normal plants, and 
 Mayer has demonstrated that plants can utilize nitrogen 
 in ammonia, though probably not as safely and success- 
 fully in most instances as when it is taken up from nitrates. 
 There are, nevertheless, certain classes of plants that prob- 
 ably take up their nitrogen chiefly or almost wholly in 
 ammonia and in still higher soluble nitrogenous compounds, 
 for they thrive splendidly in locations where nitrification 
 is practically suspended. The foregoing applies even to 
 plants which are not supposed to derive their nitrogen 
 through the aid of symbiotic bacteria or through the pos- 
 sible intervention of mychorhiza. 
 
 A reason advanced for the usual better action of nitrates 
 than of ammonium salts is that even if the former are 
 reduced to ammonia in the soil, the change takes place 
 so gradually that the resultant ammonia does not accu- 
 mulate in sufficient amounts to cause injury. The am- 
 monia in such cases is built up through successive stages 
 into the final nitrogenous compounds of the plants, prac- 
 tically as rapidly as it is formed. 
 
 Experiments by Lehmann and others show that in 
 some cases nitrates are apparently preferable in the 
 early stages of the growth of certain plants, whereas, 
 later, ammonia gives better results ; nevertheless, in 
 the case of still other kinds of plants these conditions 
 were exactly reversed. 
 
AMMONIUM SALTS AND CALCIUM CYANAMID 161 
 
 287. Calcium cyanamid a new product. — A nitroge- 
 nous fertilizer which has been rendered possible by the 
 recent electrical development is calcium cyanamid, known 
 commercially as " nitrolime " " nitrolim " and " lime- 
 nitrogen," and in Germany as "Kalk-stickstoff." 
 
 288. The manufacture of calcium cyanamid. — The 
 process for the manufacture of calcium cyanamid, which 
 was placed on a commercial basis by Frank and Caro of 
 Berlin, Germany, is based upon the employment of cal- 
 cium carbid, which combines readily with nitrogen gas at 
 moderate temperatures, yielding the calcium cyanamid 
 
 (CaC 2 + N 2 = CaCN 2 + C). 
 
 calcium nitrogen calcium carbon 
 carbid cyanamid 
 
 The calcium cyanamid in turn may be completely decom- 
 posed by steam at high pressure, yielding ammonia and 
 calcium carbonate 
 
 (CaCN 2 + 3 H 2 = 2 NH 3 + CaCo 3 ). 
 
 calcium water as ammonia calcium 
 cyanamid high pres- carbonate 
 
 sure steam 
 
 Thus it may be used in the manufacture of ammonium 
 salts. 
 
 In the practical carrying out of the process, the calcium 
 carbid is ground coarsely and is then placed in iron tubes 
 through which, while subjected to heat, a current of nitro- 
 gen gas is passed. 
 
 It is possible to produce the carbid and cyanamid simul- 
 taneously, but in actual practice it has been found prefer- 
 able to separate the processes. 
 
 The preparation of the nitrogen gas which is required, 
 may be accomplished by passing air over red-hot copper. 
 The oxygen combines with the copper to produce copper 
 
162 FERTILIZERS 
 
 oxid, thus leaving the nitrogen gas behind. The copper 
 oxid is then reduced by passing over it, while hot, a cur- 
 rent of coal gas. 
 
 Nitrogen gas is more commonly obtained for the pur- 
 pose of the manufacture of calcium cyanamid by the frac- 
 tional distillation of liquid air. In this process the oxygen 
 is separated from the nitrogen, the former being then 
 utilized for various other purposes. 
 
 The first works for the extensive manufacture of calcium 
 cyanamid were established by an Italian company, the 
 Societa Generale per la Cianamide, of Rome, which in 
 turn embraces two companies organized for distinct 
 purposes. Works have already been established in 
 several different countries, including two in the United 
 States. 
 
 It is claimed that one electrical horse power is capable 
 of fixing 772 kilograms of nitrogen per annum, but the 
 yield actually secured in practice is only from 300 to 330 
 kilograms. 
 
 289. Changes in calcium cyanamid resulting in the 
 soil. — The calcium cyanamid is a light, fine, dark gray 
 powder. Owing to its high content of calcium oxid, it 
 readily takes on water until the lime is slaked. At the 
 same time the calcium cyanamid itself slowly decomposes, 
 according to the reaction indicated above, with gradual 
 liberation of ammonia. 
 
 The views as to the changes taking place in cyanamid 
 in the soil have undergone more or less modification. It is 
 now asserted that the first change which takes place is the 
 formation of urea 
 
 (CaCN 2 + H 2 = Ca(OH) 2 + CO(NH 2 ) 2 ), 
 
 calcium water calcium urea 
 
 cyanamid hydrate 
 
AMMONIUM SALTS AND CALCIUM CYAN AMID 163 
 
 and that the urea then breaks up through bacterial 
 agencies, forming ammonium carbonate, which by 
 nitrification is transformed into nitric acid. The nitric 
 acid reacting finally with the calcium carbonate results 
 in the production of calcium nitrate, though of course the 
 formation of other nitrates is also possible. 
 
 290. The utilization of calcium cyanamid for the manu- 
 facture of urea and other substances. — It has also been 
 found that calcium cyanamid may be utilized in the prac- 
 tical manufacture of urea ; it has likewise been employed 
 in the production of guanidin ; and even of creatin, one of 
 the substances present in human muscle and found in meat 
 extract. 
 
 291. Calcium cyanamid as a fertilizer. — As a fertilizer, 
 calcium cyanamid compares well in efficiency on heavy 
 soils with sulfate of ammonia, but it has been found to be 
 more or less toxic to young plants, due supposedly to the 
 formation at the outset, through the action of water, of 
 some dicyanamid. Such injury is said to be avoided if 
 it is introduced into the soil long enough in advance of the 
 time of seeding or planting. Calcium cyanamid has the 
 advantage over sulfate of ammonia for acid soils, of having 
 an ultimate basic, rather than acidic, effect. 
 
 292. Practical difficulties connected with calcium cyan- 
 amid. — In order to remove some of the difficulties con- 
 nected with the losses of ammonia, to facilitate handling, 
 and for other reasons, it has been proposed to mix with the 
 calcium cyanamid a small quantity of peat, but there are 
 objections to such a plan, in view of the additional cost of 
 transportation. The product as manufactured and sold 
 in the United States, for a time, was said to be subjected 
 to an additional treatment, the object of which was to 
 increase its stability and thus obviate the possible loss 
 
164 FERTILIZERS 
 
 of ammonia. In one of the processes the lime was fully 
 slaked, and nitrate of soda was said to be introduced during 
 the process to keep down the temperature. It has also 
 been proposed to treat the material with sulfuric acid to 
 a limit which would prevent the tendency to decompose 
 with loss of ammonia. Finally, it has been stated that the 
 plan of minimum hydrating has superseded the latter 
 process. In any event, the calcium cyanamid industry 
 is at present probably only in its infancy, and the recent 
 difficulties connected with its more general utilization in 
 the great fertilizer manufacturing industry will doubtless 
 be more fully overcome in the near future. 
 
 293. The output of calcium cyanamid. — The produc- 
 tion of cyanamid in the United States had reached in 1912 
 a limit of 12,000 tons per year at the factory in Niagara 
 Falls, and other works are likely soon to add greatly to 
 the output. 
 
 The total sales of cyanamid are claimed to have risen in 
 two years to 4,000,000 tons per annum. 
 
CHAPTER XV 
 
 NATURAL PHOSPHATIC FERTILIZERS 
 
 Phosphorus is said to have been discovered in 1669 
 by the alchemist Brandt, a merchant of Hamburg, while 
 searching in urine for the philosopher's stone. It was also 
 discovered independently by the chemist Kunkel, of 
 Berlin, and in 1688 it was extracted by Albinus from the 
 seeds of the mustard and cress. 
 
 The discovery of phosphoric acid was made by Margraff 
 in 1743, who by calcining it with charcoal reconverted it 
 into phosporus. 
 
 It was not until 1769 that Gohn, a Swedish chemist, 
 found phosphoric acid in bones; and a little later the 
 Swedish chemist Scheele developed a practical process of 
 recovering the phosphorus from them. 
 
 It was not until more than a century after phosphorus 
 was discovered that its mineral nature was ascertained by 
 Gohn, who found it in pyromorphite, a lead phosphate. 
 Soon thereafter the discovery of the presence of phosphorus 
 in the mineral apatite was made by Vauquelin and Klaproth. 
 
 294. Bone as a fertilizer. — The use of bone as a fer- 
 tilizer is such an ancient practice that it is now impossible 
 to establish definitely when or where it had its origin. Its 
 employment is mentioned by many English writers from 
 1653 to the beginning of the last century, and in England 
 the value of bone as a fertilizer came to be generally rec- 
 ognized much earlier than anywhere on the continent of 
 Europe. In fact, it is recorded that machines for grinding 
 
 165 
 
166 FERTILIZERS 
 
 bone were already in use in England by 1778, though they 
 were obviously crude and not calculated to reduce the 
 material to the same degree of fineness, as modern mills. 
 
 As early as 1815 the English supply of bones had become 
 so inadequate that they were imported from the continent 
 of Europe in ever increasing quantities, the importations 
 soon reaching 30,000 tons per annum. It has been stated 
 by Liebig that even the battle-fields of Leipzig, Waterloo, 
 and the Crimea were turned up by the English in their 
 search for bones. 
 
 According to Heiden, the value of bone as a fertilizer 
 was not generally recognized in Germany until from 1855 
 to 1885. 
 
 With the discovery of other phosphates the importa- 
 tions of bone into England became less, but they have 
 again increased ; for as late as 1907 it was reported that 
 46,115 tons were brought into England in a single year. 
 Of this quantity 32,800 tons came from Argentina and 
 India, and the rest from other countries. 
 
 295. The chemical composition of bone. — The com- 
 position of bone varies in different parts of the same ani- 
 mal, according to its age, health, and sometimes also with 
 the character of food which it has consumed. There is 
 also a variation in the composition of bones, similarly 
 located, in the different kinds of animals. Bone is com- 
 posed of both mineral and organic matter. The former is 
 assumed to consist chiefly of tricalcium phosphate 
 
 O O 
 
 (Ca 3 (P0 4 ) 2 or Ca<^P-0-Ca-0-P^>Ca), 
 
 though it also contains very small quantities of magnesia 
 and fiuorin. In the case of bones which are not care- 
 
NATURAL PIIOSPIIATIC FERTILIZERS 167 
 
 fully prepared, traces of fluorin, sodium, and iron are fre- 
 quently found which are present in slight residues of 
 blood. 
 
 The organic matter of the bone includes ossein, col- 
 lagen, and chondro-mucoid. The ossein when dry contains 
 about 17 per cent of nitrogen and may be converted by 
 long heating with water into glue and gelatine. The 
 following statement by Murray shows quite fully the 
 constituents and average percentage composition of the 
 fresh bones of mammals : — 
 
 Per Cent 
 
 Organic matter 
 
 67 
 • M ossein 
 
 
 6.7 
 14.6 
 25.4 = 
 
 = 4.0 nitrogen 
 
 Ash .... 
 
 [P2O5 
 . 53.3 CaO 
 
 [ Mg. F, 
 
 etc. 
 
 22.3 = 
 29.2 
 1.8 
 
 = 48.7 Ca 3 (P0 4 ) 2 
 
 100.0 100.0 
 
 296. Composition of the ash. — When bones are burned, 
 only the mineral matter remains behind, and this is known 
 as bone ash. If bones, on the other hand, are treated for 
 a long time with dilute hydrochloric acid, the mineral 
 matter is dissolved and the organic framework of the bone 
 remains, still possessing its original form. 
 
 297. Composition of weathered bones. — In the case 
 of bones which have been burned for a time, or which have 
 lain exposed to the weather, considerable of the organic 
 matter has been lost, and they are therefore poor in nitro- 
 gen, but richer in phosphate than fresh bone. 
 
 298. Treatment of bone for the removal of fat. — The 
 treatment of bones for the removal of fat may consist in 
 boiling, steaming at high pressure, or extraction with 
 naphtha or other solvents. The fat is in such demand 
 and has such a high commercial value that it is now 
 
168 FERTILIZERS 
 
 usually removed from bones, more or less completely, be- 
 fore they are marketed for fertilizer purposes. The bones 
 are ground and sold as fine or coarse ground bone, accord- 
 ing to the degree of fineness. Such bone usually contains 
 from 1.5 to 4 per cent of nitrogen. 
 
 After the extraction of the fat by means of a solvent, or 
 by boiling in water, bones are sometimes subjected to high 
 steam pressure for the removal of gelatine. In some cases, 
 also, the bone is treated directly with steam at high pres- 
 sure, which removes most of the fat and much of the ossein 
 in a single operation. After bones have been steamed in 
 this manner, they crumble readily and can be ground with 
 ease to a fine powder. The material is sold in this country 
 under the name of " fine-ground steamed bone," although 
 the designation " steamed " is often omitted. 
 
 299. Effect of steaming on the nitrogen content. — 
 Bone, if subjected to severe steaming, may not contain 
 more than from 1 to 1.5 per cent of nitrogen instead of 
 from 2 to 4 per cent, as would otherwise be the case. 
 On account of the removal of so much of the organic 
 matter in such cases, the content of phosphoric acid 
 may rise to from 27 to 30 per cent, which is from 5 to 6 
 per cent above the amount usually found in commercial 
 bone. 
 
 300. Bone wastes from industries. — Bone is used for 
 the manufacture of buttons, knife handles, and a vast 
 number of other articles; the wastes from which are 
 ground and sold as bone meal or are used in compound- 
 ing commercial fertilizers. 
 
 When bone is subjected to destructive distillation, animal 
 charcoal, containing about 10 per cent of carbon, is pro- 
 duced, in a manner analogous to the production of wood 
 charcoal from wood. This material is employed in sugar 
 
NATURAL PIIOSPHATKJ FERTILIZERS 169 
 
 refineries for clarifying sugar solutions, and when no longer 
 fit for such use it is either reduced to bone ash, or it is 
 treated with sulfuric acid. By the latter process the bone- 
 black is transformed into a superphosphate known com- 
 mercially as " vitriolated " or " dissolved " bone-black. 
 Bone is sometimes used in the process of annealing, as a 
 result of which it loses much of its nitrogen and becomes 
 highly carbonized, consequently closely resembling bone- 
 black. Such material, though occasionally sold for use 
 directly as a fertilizer, should preferably be treated with 
 sulfuric acid before its application to the soil. 
 
 301. Fermentation and other methods of disintegrating 
 bone. — In England and elsewhere bones are sometimes 
 moistened with water and allowed to ferment in heaps, 
 which process renders them more available. 
 
 Bones have also been treated in tanks with urine from 
 cow stables which causes them to gradually soften and 
 disintegrate. 
 
 The process of steaming increases greatly the solubility 
 of bone in ammonium citrate, and it is usually conceded to 
 greatly increase the availability of the phosphoric acid to 
 plants, though it has been found by Kellner, in Japan, in a 
 moist and hot climate, that bone before steaming was even 
 more available than afterwards. 
 
 302. Bone meal as a fertilizer. — ■ The most ideal soils 
 on which to use " undissolved " bone meal, whether 
 steamed or raw, are those which are open and inclined 
 to be sandy or gravelly, though they should not be too 
 dry. On the other hand, bone acts more slowly on heavy 
 clay and silt soils. 
 
 For many years bone meal was the favorite fertilizer 
 of the American farmer, not only on account of its well- 
 known power to immediately increase crops to a consider- 
 
170 FERTILIZERS 
 
 able extent, but chiefly because of its accredited lasting 
 qualities. (See Fig. 14.) 
 
 In recent years the use of acid phosphate and of other 
 superphosphates has increased to such an extent as to keep 
 bone down to a price which still admits of its frequent 
 agricultural use. At the same time, on account of the 
 greater demand for vegetables and for early garden 
 crops, which must reach a marketable stage in the shortest 
 possible time, many farmers have come to a realization of 
 the fact that it is often better oconomy to expend money 
 for quick-acting acid phosphate rather than to tie up in the 
 soil, for some years, a large investment in bone. 
 
 Bone meal is a favorite substance for application before 
 seeding land to clover and grass. It is also much used for 
 fruits, hops, and for crops which require a long season in 
 which to mature. 
 
 If bone meal is applied continually for many years to a 
 soil in need of liming, it very gradually tends to correct 
 the condition ; but not rapidly enough to justify waiting 
 for it to do this work. In fact, basic slag meal is far more 
 efficient in this direction than bone meal, and it is at the 
 same time a more quickly available phosphate. 
 
 For plants and soils which need liming, it is always 
 more economical to lime the land at the outset, no 
 matter what the form of phosphate to be used, than to 
 wait for the phosphate to gradually correct the exist- 
 ing conditions. 
 
 303. The soluble and reverted phosphoric acid of bone. 
 — Ground raw bone and steamed bone rarely yield much 
 more than 0.5 per cent of " soluble " phosphoric acid 
 upon long and thorough leaching with distilled water, 
 and raw bone is but slightly soluble in neutral ammo- 
 nium citrate solution, at the usual temperature of 65° C. 
 
NATURAL PIIOSPHATIC FERTILIZERS 171 
 
172 FERTILIZERS 
 
 at which " reverted " phosphoric acid is determined. 
 Steamed bone, on the contrary, yields a considerable per- 
 centage of reverted phosphoric acid, which, added to the 
 soluble, makes up the " available " phosphoric acid re- 
 ported by analysts. It is probable that the reverted or 
 available phosphoric acid of bone is nevertheless not so 
 readily utilizable by plants as " back-gone," or true re- 
 verted phosphoric acid (dicalicum phosphate), which is 
 produced by the direct action of lime or of tricalcium phos- 
 phate upon soluble phosphoric acid (monocalcium phos- 
 phate). 
 
 304. Bone tankage. — Bone tankage contains widely 
 varying percentages of phosphoric acid and nitrogen, 
 ranging from 9 to 20 per cent of the former and usually 
 from 4 to 8 per cent of the latter. 
 
 What has been said of steamed bone applies to the tank- 
 age produced by subjecting the waste bones of slaughter- 
 houses and meat markets to the action of superheated 
 steam. It is not infrequently the case that as much as 
 one-half of the total phosphoric acid of such tankage is 
 rendered soluble upon treatment in the conventional 
 manner with neutral ammonium citrate solutions at 65° C, 
 and it hence appears in the statement of the analysis as 
 reverted phosphoric acid. What has been said of the use 
 of bone in the previous section applies equally to the prac- 
 tical employment of tankage. 
 
 305. Fish as a source of phosphoric acid. — The refuse 
 fish from the menhaden oil factories often contain, in 
 addition to the 6 to 8 per cent of nitrogen, from 5 to 7 per 
 cent of phosphoric acid. Fish heads and skeletons from 
 fish works are often still richer in phosphate. Such fish 
 wastes are often dried, ground, and sold directly to farm- 
 ers ; they are also introduced into commercial fertilizers, 
 
NATURAL PHOSPHATIC FERTILIZERS 173 
 
 especially in the manufacture of the goods sold under the 
 name of " fish and potash." 
 
 306. The nature of floats. — The name " floats " was 
 given originally to an especially fine dust product which 
 was formed in connection with the ordinary grinding of 
 phosphate rock, but it is now often applied to any finely 
 ground, unacidulated tricalcium rock phosphate. 
 
 307. Soils on which to use floats. — This phosphate 
 is especially applicable on peat or muck soils, as has been 
 abundantly demonstrated in the course of the experiments 
 on the renovation of the acid peat (Hochmoor) soils of 
 northern Germany. Next to peat and muck soils, this 
 material is useful on such upland soils as are exceptionally 
 rich in acid vegetable matter. The profitable use of such 
 phosphates has been especially pointed out by Hopkins in 
 his work with the black soils of the Illinois corn belt. This 
 phosphate is much less applicable on light, open, sandy, 
 and gravelly soils than on those previously mentioned. 
 
 308. The action of manure on floats. — According to 
 pot experiments by Hartwell and Pember 1 and to ex- 
 periments by The. Remy, 2 the mixing of the raw trical- 
 cium phosphate with stable manure and decomposing 
 materials does not materially increase its efficiency. In 
 fact, the field experiments at the Ohio station which have 
 been frequently cited elsewhere to prove the contrary 
 were not conducted in such a manner as to furnish posi- 
 tive evidence on this point either pro or con. It still 
 remains to be conclusively demonstrated that floats are 
 rendered more effective by being introduced either into 
 the manure directly or by scattering them in the gutters 
 behind the farm animals. 
 
 1 Bulletin 151, R. I. Station. 
 
 2 Bonn. Landw. Jahrb., 40, 559-611 ; Abs. Chem. Abstracts, 6, 1048. 
 
174 FERTILIZERS 
 
 309. How floats should be used. — It is true of floats, 
 as of other rather insoluble phosphates, that the best way 
 to apply them is to incorporate them thoroughly with the 
 soil ; for their availability is affected not only by the car- 
 bonic acid brought into the soil by the rain and produced 
 therein by the decay of vegetable matter, and by contact 
 with acidic matter in the soil, but also by the nitric acid 
 resulting from active nitrification. 
 
 Floats are obviously most applicable to those plants 
 which have a long season of growth, and least of all for 
 such garden or trucking plants as must be pushed rapidly 
 to maturity. In the latter case the crops must not only 
 reach the market at the earliest possible moment, but the 
 growth must be rapid in order that they may be tender and 
 acceptable to the consumer. Again, floats are less ap- 
 plicable for those plants which possess a low feeding 
 power for phosphoric acid, such as the turnip, cabbage, 
 and certain other similar plants, than for crops possessing 
 a greater feeding power, as, for example, Indian corn, 
 millet, clover, and certain grasses. Indeed, this difference 
 in the requirement for readily available phosphoric acid 
 has been well established by field experiments at Rotham- 
 sted, by many European experimenters, and by Brooks 
 and others in the United States. 1 Nevertheless, it is 
 claimed that certain of the cruciferous plants can utilize 
 raw phosphates better than either the oat or vetch can 
 utilize them. 2 
 
 310. Liming in connection with the use of floats. — 
 The advice is often given never to lime land to which 
 floats are to be applied on the ground that the lime, if 
 freshly burned or hydrated, will absorb carbonic acid 
 
 1 See Buls. 114 and 118 Agr. Expt. Sta. of the R. I. State College. 
 
 2 Centralb. f. Agrikulturchemie, 39 (1910), 495. 
 
NATURAL PUOSPHATIC FERTILIZERS 175 
 
 which might otherwise serve to attack the floats and 
 render them more available. Another reason often given 
 is based upon the known greater solubility of calcium 
 carbonate than of tricalcium phosphate in carbonic acid. 
 On this account the carbonic acid would be expected to 
 be utilized in dissolving calcium carbonate, before it would 
 attack the tricalcium phosphate to an appreciable ex- 
 tent. Admitting that this might be sound advice as 
 concerns a soil already well supplied, naturally or artifi- 
 cially, with reasonable amounts of calcium carbonate, 
 it does not, nevertheless, apply in all cases on such soils 
 as are naturally deficient in calcium carbonate, especially 
 if they are of a quite acid character. In order to make 
 this point plain, it should be stated that a soil may be so 
 acid that given varieties of plants will not thrive well 
 upon it, and hence no matter how much phosphoric acid 
 is made available by the action of carbonic acid, nitric 
 acid, or otherwise, the plants cannot utilize it, because 
 another factor has become the one which limits growth. 
 Under such circumstances, therefore, enough lime must 
 be applied to make the soil a suitable habitat for the 
 plant, even though upon theoretical grounds, and with- 
 out reference to the plant to be grown, the omission of 
 lime would seem to be advisable. If, on the contrary, 
 plants are grown which, like golden millet, serradella, and 
 certain lupines, thrive well on acid soils, the advice about 
 avoiding the use of lime, even on moderately acid soils, 
 might nevertheless be sound. (See Fig. 15.) 
 
 311. Apatite or phosphorite. — The terms "apatite" 
 and " phosphorite" have come to be used interchangeably, 
 although the latter is the term preferred for commercial 
 purposes. 
 
 Distribution in soils. — Apatite is a phosphate which is 
 
176 
 
 FERTILIZERS 
 
 & U • 
 
 a § as 
 
 a * ^ 
 
 £ oi.SP 
 
 - S 
 
 1*3 
 
 fe ft 
 
 CQ 
 
NATURAL PIIOSPTIATIC FERTILIZERS 177 
 
 widely distributed in minute crystals in most soils, and 
 especially in rocks of igneous origin. This phosphate 
 has probably been the source of the phosphorus in the 
 organic matter, and in other combinations, in most soils 
 of such derivation. It has been assumed that in many 
 cases, minute crystals of apatite are formed in the soil 
 under normally existing conditions, although laboratory 
 experiments made in the attempt to produce them, in a 
 wet way, have thus far failed. 
 
 312. The chemical composition and occurrence of 
 apatite. — The pure crystals of apatite are usually blue 
 or green, although they may be gray, white, and 
 transparent. The mineral, if pure, is a fluor-apatite 
 corresponding closely to the formula 3 Ca 3 P20 8 + CaF 2 . 
 Occasionally, however, the fluorin is wholly or partially 
 replaced by chlorin, in which case the apatites are lighter 
 in color and are designated as chlor-apatites. The pure 
 fluor-apatite contains about the equivalent of 92.25 per 
 cent of tricalcium phosphate, and 7.75 per cent of calcium 
 fluorid. A sample of Norwegian apatite examined by 
 Voelcker was found to have the following composition: — 
 
 Per Cent 
 
 Tricalcium phosphate 90.07 
 
 Calcium chlorid 6.13 
 
 Calcium fluorid ■ . 2.54 
 
 Oxid of iron . . . . . i ■ . . . 0.29 
 
 Alumina . 0.38 
 
 Potash and soda 0.17 
 
 Water 0.42 
 
 Apatites are found in several places in Renfrew and 
 Lawrence counties in Canada, where beautiful large 
 crystals occur, likewise in the Province of Estramadura, 
 Spain. They also occur in Portugal, Norway (near Chris- 
 tiania), and elsewhere. Apatite is often found in veins 
 
178 FERTILIZERS 
 
 mixed with quartz, as nodules in certain sand-stones, in 
 carboniferous slates, and as cementing material in rocks. 
 Many of the apatites occur in massive or amorphous forms. 
 
 For several years the apatites of Canada, containing 
 the equivalent of 80 to 86 per cent of tricalcium phos- 
 phate, those from Norway, containing the equivalent 
 of 70 to 90 per cent of tricalcium phosphate, and the 
 deposits in Spain, containing the equivalent of from 70 
 to 85 per cent of tricalcium phosphate, were worked quite 
 extensively ; but these phosphates have since been largely 
 replaced by those from Algeria, Florida, Tennessee, and 
 from many other sources. At present renewed interest in 
 them is being awakened in view of their possible utilization 
 by the process of Palmaer (see Section 340) . 
 
 When apatite is reduced to a powder and is subjected 
 to the action of pure water, the resulting solution gives 
 an alkaline reaction with phenolphthalein or litmus, 
 whereas the ordinary tricalcium phosphates yield an acid 
 solution with the same indicators. The solubility of 
 apatite is about seven times as great in a saturated solu- 
 tion of carbon dioxid as in water, but even then more lime 
 than phosphoric acid is dissolved. The presence of even 
 a small amount of carbonic acid in solution also increases 
 its solubility. 
 
 313. Wagnerite. — The mineral Wagnerite is a mag- 
 nesium fluor-apatite corresponding to the calcium fluor- 
 apatite. There exists also a corresponding ferrous salt 
 known as triplite, but neither of these is of importance as 
 a soil mineral or from the fertilizer standpoint. 
 
 314. Coprolites. — The term " coprolite " from two 
 Greek words meaning " dung " and " stone " was given 
 by Buckland to certain peculiarly shaped stones found in 
 the Lias marls chiefly at Lyme-Regis and also near Bristol, 
 
NATURAL PHOSPHATIC FERTILIZERS 179 
 
 England, which were said to resemble fossil fir cones. 
 They are from 2.5 to 4 or even in extreme cases 8 inches 
 in length, somewhat flattened, and ranging in color from 
 ash gray to black. The coprolites were found in deposits 
 with remains of the Ichthyosaurus and the bones and 
 teeth of fish, which coupled with the fact that their struc- 
 ture resembled that of fossilized animal excreta, led to 
 the belief that they were chiefly the excreta of reptiles of 
 the extinct group of saurians. The term " coprolites " was, 
 however, also applied to phosphates which are now known 
 to be of undisputed concretionary character. The latter 
 have also been called pseudo-coprolites in order to dis- 
 tinguish them from those of faecal origin. 
 
 Coprolites are by no means confined to England, for they 
 occur in France, Russia, and elsewhere. 
 
 The concretionary origin is supposed to be the result 
 of the replacement of the carbon dioxid of calcium car- 
 bonate by phosphoric acid, in the presence of moisture 
 and vegetable matter. 
 
 The coprolites are usually associated with considerable 
 calcium carbonate, also with calcium fluorid, oxids of 
 iron, alumina, silica, and small amounts of organic matter. 
 They usually contain from 50 to 60 per cent of tricalcium 
 phosphate. 
 
 315. Phosphatic guanos. — Where birds deposit large 
 quantities of excreta in humid locations the material 
 gradually loses its nitrogen until the residues finally be- 
 come mineral phosphates. 
 
 The Island of Lobos yields a guano with only from 2 to 
 3 per cent of nitrogen. This represents a stage between 
 the true guano with a high nitrogen content and these 
 true phosphatic guanos. These phosphates often con- 
 tain, as might be expected, traces of nitrogen and alkalies, 
 
180 FERTILIZERS 
 
 but the amounts are too small to be of any practical 
 account. 
 
 Such guanos often contain from 70 to 80 per cent of 
 tricalcium phosphate and usually but small quantities of 
 iron and aluminum. These characteristics, and the ease 
 with which they can be pulverized, make them well 
 adapted to the manufacture of superphosphate. 
 
 The phosphatic guanos known as Aruba, Navassa, 
 Sombrero, and Curacao are found in the West Indies. 
 The Mejillones guano comes from Bolivia, and large quan- 
 tities have been found on the Baker, Abrolhos, Christmas 
 and Oceanic islands in the Pacific, and elsewhere. Some 
 of these guanos have an average content of 80 to 85 per 
 cent of tricalcium phosphate. Many of the original 
 deposits have been exhausted, but the phosphate is still 
 being imported from the Oceanic and Christmas islands, 
 and from a large number of other islands of the Pacific. 
 
 Clipperton Island in the open sea off the coast of Brazil 
 is covered with a bed of phosphatic guano six feet deep. 
 It contains from 83 to 86 per cent of tricalcium phosphate 
 and only traces of iron and alumina. 
 
 316. Nassau or Lahn phosphate. — The so-called 
 Nassau or Lahn phosphate is found in Germany and 
 these deposits were worked extensively following their 
 discovery in 1864. They contain from 35 to 70 per cent 
 of tricalcium phosphate ; but such large amounts of iron 
 and alumina are present as to make them objectionable 
 for the manufacture of superphosphate. Germany has 
 at present practically no workable phosphate deposits. 
 
 317. French, Belgian, and Portuguese phosphates. — 
 The Departments of Pas de Calais, Somme, and Oise, in 
 France, contain valuable deposits belonging to the Cre- 
 taceous period ; and many other sections of the country 
 
NATURAL PIIOSPIIATIC FERTILIZERS 181 
 
 also contain very extensive deposits, though often in thin 
 beds. 
 
 Phosphate deposits at Mesvin and at Cipley near Mons, 
 Belgium, have been worked extensively. The lower 
 grades from these deposits contain from 25 to 30 per cent 
 of tricalcium phosphate. The better grades, which occur 
 chiefly in pockets, contain from 45 to 60 per cent of tri- 
 calcium phosphate. This phosphate is light brown and 
 has practically the appearance of oolite. It crumbles 
 easily and owing to its peculiar structure it has at times 
 been imported into the United States in small amounts 
 for use as a drier in mixed fertilizers, in order to make 
 them more drillable. 
 
 Other phosphate deposits exist in the district of Liege 
 and elsewhere in Belgium. 
 
 Phosphates somewhat similar to those of Cipley have 
 been found in France, Portugal, and elsewhere and, al- 
 though they are often quite rich in tricalcium phosphate, 
 they contain clay and marl in quantities objectionable 
 from the standpoint of the superphosphate manufacturer. 
 An exception is however afforded by the Somme phos- 
 phates of northern France which are richer in tricalcium 
 phosphate, and contain less iron and aluminum oxids. 
 In utilizing them for the manufacture of superphosphate 
 it is considered desirable or necessary to employ hot 
 rather than cold sulfuric acid. 
 
 318. The phosphates of Russia and Northern Africa. — 
 In Russia there are large numbers of phosphate deposits, 
 the best of which are in central Russia. They are dis- 
 tributed over an area estimated at 50,000,000 acres. 
 
 One of the chief sources of phosphate for Europe, at 
 present, is the great deposit supposed to stretch practically 
 across the northern part of the continent of Africa, though 
 
182 FERTILIZERS 
 
 Morocco has not as yet been carefully examined. The 
 centers of export are Algeria and Tunis from which ap- 
 proximately two millions of tons are now shipped annually. 
 
 The amount of tricalcium phosphate usually present 
 in the material as exported is about 60 per cent, but by 
 careful selection it may run as high as 70 per cent. 
 
 The beds thus far explored in Egypt yield a phosphate 
 containing only from 40 to 50 per cent of tricalcium phos- 
 phate, which is too low for present profitable exportation. 
 These deposits underlie the Eocene ; and the phosphate- 
 bearing strata usually range from 7 to 10 feet in depth. 
 
 One great advantage of these phosphates is that they 
 contain only little iron and alumina. When used in an 
 unacidulated form in comparison with the Florida phos- 
 phate, on the Hochmoor (acid peat) soils of northern 
 Germany, they have been reported as being superior to 
 the American product. 
 
 319. The phosphates of South Carolina. — Until within 
 the last twenty years the main source of phosphate for 
 the United States was South Carolina. The chief supply 
 for Europe came also from the same source until the dis- 
 covery of the high grade African deposits. Many of 
 these phosphates are essentially nodular and belong at 
 the bottom of the Eocene period ; others consist of phos- 
 phatic limestones alternating with the nodular deposits. 
 The material resembles somewhat that at Cipley in Bel- 
 gium. Associated with the phosphates, in the beds of 
 marl, are teeth and bones of sharks. The phosphate, 
 however, has been redeposited from solution in carbonic 
 acid and in organic acids, and is still being formed. 
 
 The so-called " river " phosphate was secured by dredg- 
 ing the bottoms of rivers, whereas the usual methods of 
 mining prevail in connection with the land phosphates. 
 
NATURAL PHOSPLTATIC FERTILIZERS 183 
 
 The former contain usually about 60 per cent of trical- 
 cium phosphate, but they are preferable for the manufac- 
 ture of superphosphate to the richer (70 to 80 per cent) 
 land phosphate on account of their containing less iron 
 and aluminum oxids. 
 
 320. The Florida phosphates. — The discovery of 
 phosphates of the Oligocene period in Florida in 1887, 
 followed by their extensive exploitation, focused the 
 attention of the entire world upon them. 
 
 The black, river, pebble phosphate containing 60 to 70 
 per cent of tricalcium phosphate was formerly dredged in 
 large quantities from beds of streams, but such mining in 
 the Peace River district has now been abandoned. 
 
 The land pebble phosphate, which bears much resem- 
 blance to calc-sinter, is found in Florida in large quantities ; 
 and the output has reached as much as 1,250,000 tons per 
 annum. It is consumed chiefly in the United States. 
 It contains from 66 to 75 per cent of tricalcium phosphate 
 and an average of 2.3 per cent of iron and aluminum oxids, 
 though the latter usually fall below 2 per cent. The 
 masses are rounded, flattened and of a yellowish to white 
 color and occur associated with occasional stringers of 
 quartz sand. The deposits resemble gravel beds in cer- 
 tain respects. 
 
 The better grades of land phosphate, to which the terms 
 " rock " and "bowlder " phosphate are applied, vary less 
 in composition than the pebble phosphates and are sold 
 on a guaranty of 77 per cent of tricalcium phosphate, but 
 they not infrequently contain as much as 80 per cent. 
 This is much in excess of the amount in the South Carolina 
 phosphate. They frequently, however, contain as much 
 as 6 per cent of iron and aluminum oxids which is a highly 
 objectionable feature. 
 
184 FERTILIZERS 
 
 Soft phosphate. — The Florida " soft " phosphate, con- 
 taining from 25 to 70 per cent of tricalcium phosphate 
 and 3 to 7 per cent of iron oxid and alumina, is usually 
 associated with such large quantities of calcium carbonate 
 or earthy matter, as to render it unsuitable for the most 
 economical manufacture of superphosphate. For this 
 reason it has been ground and utilized to a considerable 
 extent for direct application to the land, and likewise as 
 a drier in the manufacture of commercial fertilizers. 
 
 321. The Tennessee phosphates. — Upon the dis- 
 covery of the great phosphate deposits of Tennessee in 
 1894, following closely upon those in Florida, it was con- 
 sidered that inexhaustible supplies were at hand; the 
 quantity mined has, however, reached from two to three 
 million, tons per annum and it is now estimated by the 
 U. S. Geological Survey that the exhaustion of these deposits 
 will be accomplished in another generation, if the mining 
 increases at as great a rate as is to be expected. 
 
 322. Phosphates of the Western States. — In view of 
 the rapid exhaustion of the phosphate beds of the eastern 
 United States, the recent discovery of high grade phos- 
 phate fields in Idaho, Wyoming, and Montana, which 
 are now believed to be the greatest thus far discovered in 
 the world, is hailed with great satisfaction by those in- 
 terested in the future prosperity of the United States. 
 In each of the nine townships thus far examined it is 
 estimated that there are not less than 60,000,000 tons of 
 high grade phosphate rock, and in one of the townships 
 the estimate reaches 293,000,000 tons. 
 
 The preceding estimates do not embrace 34,000 acres 
 of Montana phosphate beds previously withdrawn from 
 the lands opened for settlement. These figures are es- 
 pecially significant when one recalls that but about 39,000- 
 
NATURAL PHOSPHATIC FERTILIZERS 185 
 
 000 tons of phosphate rock have thus far been mined in 
 the United States. 
 
 Certain of these western deposits are situated reason- 
 ably near great copper smelters which are capable of pro- 
 ducing enormous quantities of sulfuric acid as a cheap by- 
 product, so that the conditions are especially favorable 
 for the manufacture of acid phosphate or of other even 
 richer products. In the case of some of the latter the cost 
 of transportation, per unit of phosphoric acid, would be 
 but one-third of the cost in ordinary acid phosphate. 
 
 323. Occurrence and composition of certain aluminum 
 phosphates. — Aluminum phosphate, associated with some 
 iron phosphate, is found on the Islands of Grand Conne- 
 table, a French possession on the coast of French Guiana ; 
 on the Island of Redonda (where the mineral redondite 
 occurs) , near the Island of Montserrat in the British West 
 Indies ; and on the Islands of Alta Vela, Sombrero, and 
 Navassa. The material from the Island of Redonda often 
 contains as much as 35 to 36 per cent of phosphoric acid, 
 combined almost wholly with alumina. It may never- 
 theless contain in some cases as little as 20 per cent of 
 phosphoric acid. The phosphates from Alta Vela, Som- 
 brero and Navassa, contain about 22, 31, and 31 per cent 
 of phosphoric acid, respectively. 
 
 Wavellite. — The mineral Wavellite is a crystallized 
 aluminum phosphate (3 A1 2 3 • 2 P 2 5 • 12 H 2 0) which, 
 though possibly formed in a wet way, is supposed by 
 certain writers not to be generally present in soils. 
 
 324. Roasting increases the efficiency of aluminum 
 phosphate. — The efficiency of these phosphates is greatly 
 increased by subjecting them to a roasting process. This 
 fact is not new but it has been recently well shown in 
 trials of the roasted and unroasted product, at the experi- 
 
186 FERTILIZERS 
 
 ment station of the Rhode Island State College, 1 and later 
 in the course of experiments by Fraps. The Rhode Is- 
 land experiments have shown in a most striking manner 
 the effect of slaked lime in increasing the crop-producing 
 efficiency of the roasted, in contrast with the unroasted, 
 Redonda phosphate. Furthermore, this effect con- 
 tinues for several years after the last application of each 
 substance is made to the soil. (See Figs. 16 and 17.) 
 
 325. The solubility of artificial aluminum phosphate. — 
 The solubility of artificial aluminum phosphate appears, 
 according to Gerlach, not to be increased by the presence 
 of carbon dioxid in solution, even in the presence of lime 
 and magnesia, but its solubility is greatly increased by 
 sodium and potassium hydroxids and in a lesser degree 
 by free mineral acids. As concerns oxalic and citric acids, 
 they differ but little in their solvent action upon the phos- 
 phoric acid of aluminum phosphate, and both are far 
 superior in this respect to acetic acid. The presence of 
 aluminum hydroxid while lessening the solvent action of 
 acetic acid had no effect upon the action of citric and oxalic 
 acids. 
 
 According to Schneider 2 both aluminum chlorid and 
 aluminum sulfate, which give acid solutions, increase the 
 solubility of aluminum phosphate. 
 
 The action of water upon several artificial preparations 
 of aluminum phosphate of varying degrees of basicity, 
 has been determined by Cameron and Hurst, 3 from which 
 it appears that the total quantity of phosphoric acid dis- 
 solved, increased with the volume of water ; but that the 
 concentration of the solution became less as the quantity 
 
 1 Bulletins Nos. 114 and 118. 
 2 Zeit. anorg. Chemie., 5 (1894), 87. 
 3 Jour. Am. Chem. Soc., 26 (1904), 385. 
 
NATURAL PHOSPHATIC FERTILIZERS 
 
 187 
 
 o 
 
 > CO 
 
 
 •S d 
 
 5 (CO 
 
 p "S -2 
 
 d o 
 
 co d 
 
 ft ft a 
 
 3 *g 
 
 pq 
 
 w se 
 
 ea 3 
 
 g o g 
 
 ■G 43 
 
 to a 
 
 - « ° d 
 
 3 <p 
 
 d S 
 
 <S CO 
 43 
 
 CO 
 
 CO <u 
 
 £ e 
 
 M 
 
188 FERTILIZERS 
 
 of the water was increased. A greater removal of phos- 
 phoric acid than of aluminum was shown, analogous to 
 the case of the iron phosphate (Section 327). The same 
 investigators found that aluminum phosphate behaves, 
 toward solutions of potassium chlorid, in a similar manner 
 as the calcium and iron phosphates ; or in other words, 
 that with an increase in the concentration of the chlorid 
 the phosphoric acid in the solution became less. Similar 
 results were noted also with potassium sulfate and with 
 sodium nitrate. It appears therefore, that, like iron 
 phosphate, the solubility of aluminum phosphate is af- 
 fected much less by neutral salts than by acid or alkaline 
 solutions. 
 
 326. Iron phosphate formed in soils. — The phosphate 
 of iron is formed wherever dissolved phosphate is brought 
 in contact in the soil with oxid of iron. 
 
 Phosphates of iron are often found associated with peat 
 deposits, where through the reducing action of vegetable 
 matter ferrous phosphate (the phosphate of the protoxid 
 of iron) often occurs in large quantities. 
 
 Vivianite. — A ferrous phosphate, known as Vivianite 
 (Fe 3 (P0 4 )2 • H 2 0), occurs as a mineral, but it has not 
 yet been proved to be common in soils, although this 
 has been assumed by some writers. 
 
 327. The solubility of artificial ferric phosphate. — 
 Experiments have been made by Lachowiez * with arti- 
 ficially prepared ferric phosphate which contained phos- 
 phoric acid considerably in excess of that (47.02 per cent) 
 corresponding to the formula FeP04 . Such phosphate, 
 after various treatments with hot or boiling water, yielded 
 acid solutions containing but minute quantities of iron. 
 The quantity of phosphoric acid in the residues after the 
 
 1 Monatsh., 13 (1892), 357, cited from Cameron and Bell, 
 
NATURAL PHOSPHATIC FERTILIZERS 189 
 
 various treatments was lowered from 48.14 per cent to a 
 minimum of 46.33 per cent. At the same time the per 
 cent of Fe 2 3 was raised from 48.97 (the formula 
 FeP0 4 requires 52.98 per cent) to a maximum of 61.98 
 per cent. After a considerable number of days a con- 
 dition of equilibrium is reached between the solid and the 
 solution. In order therefore, to effect a further removal 
 of phosphoric acid fresh quantities of water are required. 
 It has been inferred that it is possible, by a sufficient 
 number of successive treatments with water, to remove 
 all of the phosphoric acid, in which case only ferric hy- 
 droxid would remain. These results have been confirmed 
 by Cameron and Hurst, who also experimented with a 
 basic phosphate without however finding that it mate- 
 rially altered the character of the results. The presence 
 of neutral salts, at least in certain concentrations, has no 
 material effect upon the amount of phosphoric acid brought 
 into solution, whereas salts having an alkaline reaction, 
 as for example alkaline carbonates, increased the solvent 
 power of the solution for the phosphoric acid of the ferric 
 phosphate. The solubility was found to be especially 
 marked in the case of the presence in solution of the car- 
 bonates and acetates of sodium and potassium. The 
 same is also true of disodium phosphate, notwithstanding 
 the probable formation in this case of a common ion. 
 
 Iron phosphates are soluble in alkali hydroxids and less 
 readily in solutions of free mineral acids. Their solubility 
 is also increased by the presence of salts which when hy- 
 drolized yield alkaline solutions. 
 
 It was found by Gerlach 1 that oxalic acid was a more 
 effective solvent of artificial iron phosphate than citric acid 
 and that this was even much superior to acetic acid. In 
 
 i Landw. Vers.-Sta., 46 (1895), 201. 
 
190 FERTILIZERS 
 
 the presence of free iron hydroxid, acetic acid had no ap- 
 preciable solvent effect on the iron phosphate. Citric 
 acid had far less effect under the same condition than other- 
 wise, whereas the solvent action of oxalic acid was not in- 
 fluenced. 
 
 It was found by Cameron and Bell that there was a great 
 and unexpected increase in acidity when iron phosphate 
 was treated with solutions of certain neutral salts. This 
 they attribute to selective absorption whereby the basic 
 part unites with the solid residues leaving free acid in 
 solution. 
 
 It is asserted that the presence of calcium carbonate 
 may increase the solubility of iron phosphate, but in this 
 particular calcium bicarbonate is far more effective. 
 
CHAPTER XVI 
 
 MANUFACTURED PHOSPHATES AND STUDIES OF SOLUBILITIES 
 
 In recent years, owing to the great demand for phos- 
 phatic fertilizers and on account of the wide recognition of 
 the necessity, for many purposes, of having them readily 
 available, the ground raw and steamed bone have been 
 very largely replaced by the artificially prepared phos- 
 phates. 
 
 328. The manufacture of basic slag meal. — Basic slag 
 meal (not to be confused with non-phosphatic or but 
 slightly phosphatic slags of ordinary blast furnaces) is a 
 waste product of the manufacture of steel from iron 
 phosphate by the modification of the Bessemer process 
 developed by Thomas and Gilchrist of England. This 
 consists in passing air through a mixture of molten iron 
 phosphate and lime, in a large pear-shaped converter lined 
 on the bottom and sides with a mixture of tar and lime, 
 or magnesian lime. The tar is employed in order to 
 make the lime adhere to the converter. A current of 
 air is then forced through the mass until spectroscopic 
 observations of the gases evolved show that the oxida- 
 tion is complete. The slag formed by the union of the 
 oxids of phosphorus and of silicon with lime, is then 
 poured off by decanting the converter, after which the 
 steel is drawn off below. After pulverization the slag 
 meal is sold under the name of " basic cinder," " basic 
 slag meal," or " Thomas phosphate powder." 
 
 In the earlier days of the manufacture of basic slag meal 
 
 191 
 
192 FERTILIZERS 
 
 it was found to vary greatly in its availability to plants, 
 dependent upon the works from which the material came, 
 and certain works in particular had the reputation of 
 turning out a product having a very low efficiency as a 
 fertilizer. 
 
 329. The influence of silica on the efficiency of basic 
 slag. — ■ It was finally discovered by Hoyermann of Han- 
 nover, Germany, and later fully established by the work 
 of others, that this difference in availability was caused by 
 variations in the amounts of silica which were present, 
 and that frequently by the introduction of extra silica 
 the efficiency of the resulting slag meal could be greatly 
 increased. In consequence of this discovery there is now 
 usually less difference than formerly in the availability 
 of the European product, which at present constitutes the 
 chief source of supply for the United States. 
 
 330. The range in composition of low and high grade 
 basic slag. — There is produced in certain works in Eng- 
 land a grade of basic slag meal with a very low content 
 of phosphoric acid ranging usually from 12 to 14 per cent. 
 There are on the other hand basic slag meals on the market 
 containing from 25 to 28 per cent, but the grades more 
 commonly brought into the United States usually contain 
 from 16 to 19 per cent of phosphoric acid. It has been 
 asserted that in some cases the percentage of phosphoric 
 acid is raised by the introduction of tricalcium phosphate 
 into the converter, with the result that the percentage of 
 phosphoric acid is increased at the expense of the avail- 
 ability of the product. Certain Belgian exporters claim, 
 nevertheless, that they can furnish slag meal, with the 
 higher percentages of phosphoric acid, which has not been 
 fortified in this manner. 
 
 331. The German methods of determining availability. 
 
MANUFACTURED PHOSPHATES 193 
 
 — The agricultural experiment stations of Europe busied 
 themselves for some years in the attempt to find a labo- 
 ratory method of treatment, capable of indicating essen- 
 tially the same degree of availability of basic slag meal as 
 was shown by experiments with plants. The method in 
 use prior to 1899, consisted in extracting the material, under 
 definite conditions, with an acid solution of ammonium 
 citrate, but this was then replaced by a 2 per cent solu- 
 tion of citric acid, which is used in the present official 
 German method. The purchase of basic slag meal on 
 analysis, by this method, is advisable as an insurance 
 against the introduction of ordinary tricalcium phosphate 
 as an adulterant. 
 
 332. The degree of fineness. — The degree of fineness, 
 and the total content of phosphoric acid, also furnish valu- 
 able criteria of the value of basic slag meal. In fact 80 
 per cent of it should readily pass through a sieve having 
 100 meshes to the linear inch. 
 
 333. The chemical composition of basic slag. — In 
 addition to phosphoric acid, basic slag usually contains 
 calcium, magnesium, iron as ferrous and ferric oxids, cal- 
 cium sulfid, and small quantities of oxids of manganese, 
 vanadium, silicon, and sulfur. Such amounts of metallic 
 iron as are present are usually separated by a magnet dur- 
 ing the process of pulverization. The composition of the 
 final product varies according to the composition of the 
 lime, iron ore, and other materials added in the converter. 
 
 Per Cent 
 
 Calcium oxid 40-60 
 
 Phosphorus pentoxid (Jf 2 O s ) .... 10-20 
 
 Iron oxid 10-20 
 
 Silica 5-15 
 
 Manganese oxid 3-6 
 
 Magnesium oxid 2-6 
 
 Alumina 1-3 
 
 o 
 
194 FERTILIZERS 
 
 In general the composition of basic slag meal may be con- 
 sidered as ranging between the preceding limits. 
 
 The amount of free lime in basic slag meal is now less 
 than formerly, owing to the greater amount of silica in- 
 troduced into the converters. It usually ranges from 1 to 
 6 per cent, though the upper limit, recently determined 
 by James Hendrick l in seven lots of basic slag with rather 
 low phosphorus content which were sold in England, was 
 only 3.08 per cent, as shown by the lime dissolved by long 
 shaking with a 10 per cent sugar solution. The amount 
 of lime capable of acting as a base, as determined by Hen- 
 drick in these slags, ranged from 13.6 to 28.3 per cent. The 
 method used for this determination was distillation with 
 ammonium sulfate and measurement of the equivalent, 
 by the ammonia liberated. The introduction of the extra 
 silica into the converter obviously increases the amount of 
 calcium silicate present, and lessens the quantity of free 
 lime. 
 
 334. As to the constitution of basic slag. — In case 
 basic slag is cooled slowly, certain flat, square, plate crys- 
 tals are formed, which upon analysis have been found 
 to be tetracalcium phosphate, the structure of which as 
 compared with tricalcium phosphate is shown below : — 
 
 O 
 
 Ca< >P-0-Ca-0-P< >Ca 
 
 tricalcium phosphate 
 
 o o 
 
 Ca< >P-0-Ca-0-Ca-0-P< >Ca 
 
 tetracalcium phosphate 
 1 Jour. Soc. Chem. Ind., 28, 776. 
 
MANUFACTURED PHOSPHATES 195 
 
 The tetracalcium phosphate, if reacted on by weak acids, 
 yields two molecules of calcium oxid to the acid and is 
 transformed into dicalcium phosphate. 1 
 
 It was long supposed that basic slag was strictly a tet- 
 racalcium phosphate, yet it was difficult to account for 
 all of the lime on that supposition, even with due allow- 
 ance for silica, sulfur, and for the lime which can be looked 
 upon as " free " lime. Further doubt is thrown upon the 
 basic slag being tetracalcium phosphate, by the fact that 
 the flat crystals just mentioned are not found in slag which 
 is rich in silica. The crystals usually formed under such 
 circumstances are long hexagonal needles, pale green, or 
 blue, in color, the presence of which would more readily 
 account for the peculiar fracture of basic slag than the 
 crystals of tetracalcium phosphate. These needle-shaped 
 crystals have been shown by Stead to have the composi- 
 tion (CaO)5P 2 5 Si02 which gives approximately 11 per 
 cent of silica, 29 per cent of phosphoric acid, and 56 
 per cent of lime. When these crystals are subjected to 
 the action of carbonic acid or dilute citric acid their 
 solubility is found to accord far more nearly with that 
 of basic slag meal, than the crystals of tetracalcium 
 phosphate. 
 
 335. The practical use of basic slag meal. — Basic 
 slag meal becomes especially available in the presence 
 of considerable moisture and hence it usually acts well 
 on clayey, soils ; it also improves their physical condi- 
 tion because of the presence of calcium oxid and 
 calcium carbonate. 
 
 On peat or muck soils which are acid, basic slag meal has 
 also been employed with splendid effect. Its use on sandy 
 
 1 O. Forster, Zeit. f. angew. Chemie, 18, 22 (1892) ; Jour. Soc. Chem. 
 Ind., p. 460 (1892), cited from Hendrick. 
 
196 FERTILIZERS 
 
 soils is followed by excellent results except in case of 
 extreme drought. 
 
 The ideal soils on which to use basic slag meal are acid 
 uplands, for benefit to them not only results from the phos- 
 phoric acid, but also to a moderate degree from the free 
 lime, and from the lime present as carbonate, silicate, and 
 phosphate. This is by virtue of gradually lessening the 
 soil acidity and consequently postponing the time when 
 further liming will be necessary. A single or several 
 repeated applications of basic slag meal will often bring 
 in clover and create conditions favorable to the growth of 
 timothy, barley, and other plants; whereas the use of 
 acid phosphate or of double superphosphate may, under 
 the same conditions, make the situation even slightly 
 worse. If applied to acid pasture soils, basic slag meal 
 aids in bringing in white clover, and thus materially adds 
 to their value for grazing purposes. (See Fig. 18.) 
 
 336. Care in mixing basic slag with certain other ma- 
 terials. — Care must be taken not to mix basic slag meal 
 with organic nitrogenous fertilizers in case they are to be 
 stored before their application, especially if they absorb 
 much moisture, for some loss of nitrogen as ammonia may 
 result. It is equally important not to mix basic slag with 
 acid phosphate or double superphosphate, for some of the 
 lime will be neutralized thereby and hence lose much of its 
 immediate corrective value. At the same time the lime 
 would tend to cause the reversion of some of the soluble 
 phosphoric acid, thus rendering the superphosphates less 
 valuable, particularly for the purpose of top-dressing. 
 
 If basic slag is mixed with sulfate of ammonia, the free 
 lime is sure to liberate some of the ammonia, and at the 
 same time the lime will be transformed into land plaster 
 or gypsum and hence lose its capacity for correcting the 
 
MANUFACTURED PHOSPHATES 
 
 197 
 
198 FERTILIZERS 
 
 condition of acid soils. This reaction is shown by the fol- 
 lowing equation : — 
 
 (NH 4 ) 2 S0 4 + CaO = CaS0 4 + NH 3 + H 2 
 
 sulphate of ammonia lime gypsum ammonia water 
 
 For the reasons given above, basic slag meal should 
 usually be applied to the soil by itself, though it can be 
 mixed with nitrate of soda, nitrate of potash, and with the 
 German potash salts without fear of loss or of the dete- 
 rioration of any of the ingredients of the mixture. 
 
 337. Artificial basic slag meal. — On account of the 
 popularity of basic slag meal and of the consequent in- 
 creased demand for it, many attempts have been made to 
 produce a similar product by a direct process of manufac- 
 ture. To this end apatite and other phosphates have been 
 fused with silica and lime whereby a strictly basic product 
 is said to result, resembling in many respects genuine basic 
 slag meal. Such products have been found to be soluble 
 by the usual method of treatment with ammonium citrate, 
 to the extent of 90 per cent of the phosphoric acid. 
 
 These products have been given various names, and they 
 have also been sold as (< artificial " basic slag. 
 
 338. Wiborgh phosphate. — This product has been 
 prepared by fusing together feldspar, sodium carbonate, 
 and phosphorite. It is also said to have been made with- 
 out the introduction of the feldspar. The fusion is made 
 at from 900° to 1000° C. The final product has been rep- 
 resented by the formula : 2 Na 2 • 10 CaO • 3 P 2 5 . The 
 phosphoric acid is soluble to the extent of 21 to 27 per 
 cent in a solution of ammonium citrate ; and it has been 
 found to compare favorably with superphosphate and 
 basic slag meal. It is especially adapted to the peat 
 soils of Sweden, where it has been chiefly used. It has 
 
MANUFACTURED PHOSPHATES 199 
 
 now been superseded by the Palmaer phosphate, which is 
 produced more economically. 
 
 339. Wolter's phosphate. — Another artificial product 
 quite similar to the preceding is made by fusing in a re- 
 generative furnace 100 parts of powdered phosphorite, 
 70 parts of sodium sulfate, 20 parts of calcium carbonate, 
 22 parts of sand, and 6 to 7 parts of coke. The molten 
 material is first run into water, and is at last finely pul- 
 verized. By this process the phosphoric acid is rendered 
 almost wholly soluble in a 2 per cent citric acid solution. 
 The phosphoric acid in this material has been found to be 
 even more efficient than that in basic slag meal, and but 
 slightly inferior to that in superphosphate. 
 
 340. Palmaer Phosphate. — In the Palmaer process a 
 solution of sodium chlorate or of sodium perchlorate is 
 electrolyzed. The acid anode solution is then made to 
 react on the raw phosphate, which it readily dissolves. 
 Thereupon some of the alkaline cathode solution is 
 added, as a result of which dicalcium phosphate is pre- 
 cipitated as a fine crystalline powder. After this is 
 separated by filtration, the remainder of the cathode 
 solution is added to the filtrate, whereupon most of the 
 lime in solution is separated as calcium hydrate. The 
 remainder is then removed as carbonate by the intro- 
 duction of carbonic acid. The electrolyte, thus regen- 
 erated by the process, again enters the electrolyzing 
 apparatus. 
 
 The dicalcic phosphate thus produced contains 36 to 
 38 per cent of phosphoric acid, 95 per cent of which is 
 soluble in a solution of ammonium citrate. 
 
 Experiments with this phosphate in Sweden, on sandy 
 and on peat soils, have shown its direct and residuary effects 
 to be on a par with those secured with superphosphate. 
 
200 , FERTILIZERS 
 
 On peat soil the residuary effect of Palmaer phosphate has 
 been found by Von Feilitzen to agree with acid phosphate 
 but to be somewhat inferior to that secured with basic 
 slag meal. By this process low-grade apatites can be 
 utilized. 
 
 341. Other artificial phosphates. — By heating a mix- 
 ture consisting of equal parts of 55 per cent phosphoric 
 acid and either ammonium sulfate or potassium sulfate, 
 at 80° C. there results a pulverulent product. The fol- 
 lowing illustrates the course of the reaction with potas- 
 sium sulfate : — 
 
 K 2 S0 4 + H3PO4 = KHSO4 + KH 2 P0 4 . 
 
 This product contains 24 per cent of phosphoric acid, and 
 27 per cent of potash. The corresponding product made 
 by substituting ammonium sulfate for the potassium sul- 
 fate, contains 25 per cent of phosphoric acid and 10.5 
 per cent of nitrogen. A corresponding sodium salt cannot 
 be prepared in this manner. On account of the acid 
 character of this material, due to its containing 30 per 
 cent of sulfuric acid, it may be mixed to advantage with 
 basic slag meal, at least in so far as concerns the avail- 
 ability of the phosphoric acid. It is also especially ap- 
 plicable on calcareous soils. 
 
 From low-grade calcium phosphate. — Another artificial 
 product is prepared on a similar principle by the intro- 
 duction of a low-grade calcium phosphate, too rich in 
 calcium carbonate for profitable superphosphate manu- 
 facture. By suitable processes of evaporation, filtra- 
 tion, and desiccation an excess of sulfuric acid is 
 avoided and there is produced a sulfo-phosphate con- 
 taining 38 to 40 per cent of phosphoric acid, which is 
 chiefly soluble. It also contains 31 to 33 per cent of 
 
MANUFACTURED PHOSPHATES 201 
 
 potash and small quantities of sulfuric acid, lime, and 
 other substances. 
 
 From aluminum phosphate. — Redonda phosphate and 
 other similar aluminum phosphates can be utilized, in a 
 similar way, to make sulfo-phosphates of ammonia and 
 aluminum sulfate, by fusing the phosphate with ammo- 
 nium disulfate for from two to three hours. The re- 
 action is as follows : — 2 A1P0 4 + (NH 4 ) HS0 4 + H 2 S0 4 = 
 A1 2 (S0 4 ) 3 + 2 (NH 4 )HS0 4 • (NH 4 )H 2 P0 4 ). Practical diffi- 
 culty arises in this treatment, due to the presence of 
 aluminum sulfate, but this may be obviated by adding 
 an equivalent amount of ammonium disulfate, whereupon 
 a product is obtained which remains dry. The reaction 
 is then as follows : — A1P0 4 + 3 (NH 4 )HS0 4 = A1(NH 4 ) 
 (S0 4 ) 2 + (NH 4 )HS0 4 • (NH 4 )H 2 P0 4 . 
 
 By the use of bisulfate. — A so-called " bisulfate-super- 
 phosphate " has been prepared by treating Algerian phos- 
 phate with bisulfate refuse from nitric acid works. If 
 properly managed, a dry product results which contains 
 from 7 to 8 per cent of soluble phosphoric acid. 
 
 342. The preparation of superphosphates. — In order 
 to secure a greater efficiency of phosphoric acid than is 
 possible when it is in the state of tricalcium phosphate, 
 the latter is treated with sulfuric acid. In this process 
 two-thirds of the lime combines with sulfuric acid to form 
 land plaster, or gypsum, which remains in the mixture 
 with the monocalcium phosphate (soluble phosphoric acid) 
 which is produced. The resulting mixture is called 
 " superphosphate." If made from spent bone-black, it 
 is given the name of " dissolved bone-black" ; if from 
 bone, " dissolved bone " ; and if from mineral tricalcium 
 phosphate, either " plain superphosphate " or " acid 
 phosphate." The reaction is shown by the following 
 
202 , FERTILIZERS 
 
 equation : — 
 
 Ca ? (P0 4 ) 2 + 2 H 2 S0 4 = 2 CaS0 4 + CaH 4 (P0 4 ) 2 . 
 
 tricalcium sulfuric calcium monocalcium 
 
 phosphate acid sulfate phosphate 
 
 In the practical application of the process, small quan- 
 tities of free phosphoric acid, dicalcium phosphate, and 
 tricalcium phosphate are present in the product. 
 
 343. Treatment of bone with small amounts of sulfuric 
 acid. — A few years ago much interest was awakened by 
 a proposition to use only about half the usual amount of 
 sulfuric acid, in the treatment of bone. By this means 
 the cost of the treatment was greatly lessened, and yet 
 the material produced was claimed to possess a very high 
 degree of manurial efficiency. Such a product, because 
 of its slight solubility, would, however, not be fully satis- 
 factory for the top-dressing of either grass lands or grain 
 crops. By this process only one-third of the lime would 
 be removed from the tricalcium phosphate, as suggested 
 below : — 
 
 Ca 3 (P0 4 ) 2 + H 2 S0 4 = CaS0 4 + 2 CaHP0 4 . 
 
 tricalcium sulfuric calcium dicalcium 
 
 phosphate acid sulfate phosphate 
 
 344. Free phosphoric acid in superphosphate. — If 
 more sulfuric acid is used than is customary for the pro- 
 duction of monocalcium phosphate, considerable free 
 phosphoric acid is formed ; and by employing enough 
 sulfuric acid to replace all of the lime, the following would 
 be the course of the reaction : — 
 
 Ca 3 (P0 4 ) 2 + 3 H 2 S0 4 = 3 CaS0 4 + 2 H 3 P0 4 . 
 
 tricalcium sulfuric calcium phosphoric 
 
 phosphate acid sulfate acid 
 
 345. The strictly chemical use of the term " phosphoric 
 acid." — The name phosphoric acid is properly applied 
 
MA N UFA CTUR ED PHOSPHA TES 
 
 203 
 
 only to the hydrated compound H 3 P0 4 , though it is com- 
 monly used in agricultural literature in referring to the 
 phosphorus pentoxid (P 2 5 ). 
 
 346. The relationship of the various phosphates. — 
 The relationship of the tribasic orthophosphoric acid, 
 with its three hydrogen atoms replaceable by a metal, is 
 shown below : — 
 
 [OH 
 
 PO OH 
 
 [OH 
 
 orthophosphoric 
 acid 
 
 fOM 
 
 POOH 
 | OH 
 
 monometallic 
 orthophosphate 
 
 (OM 
 
 PO OM 
 
 [OH 
 
 dimetallic 
 orthophosphate 
 
 (OM 
 POlOM 
 
 [OM 
 
 trimetallic 
 orthophosphate 
 
 The union of calcium, a divalent element, with orthophos- 
 phoric acid is illustrated as follows : — 
 
 (OH 
 
 POO/ U 
 
 POOH 
 
 o\ 
 
 o\ 
 
 Ca 
 
 Ca 
 
 (0/ 
 
 (0/ 
 
 POOH 
 
 POOH 
 
 (OH 
 
 (OH 
 
 monocalcium phos- 
 
 dicalcium phosphate 
 
 phate or acid phos- 
 
 or monacid phos- 
 
 phate of lime 
 
 phate of lime 
 
 CaH 4 (P0 4 ) 2 
 
 2 CaHP0 4 
 
 PO 
 
 PO 
 
 °\Ca 
 Q/ Ua 
 
 0\ 
 
 Ca 
 
 (0/ 
 
 °\Ca 
 
 tricalcium phosphate 
 or neutral phos- 
 phate of lime 
 
 Ca 3 (P0 4 ) 2 
 
 347. Care in the manufacture of superphosphate. — 
 In the manufacture of superphosphate the composition 
 of the raw phosphate must be determined in advance, in 
 order that the right quantity of sulfuric acid of the proper 
 strength may be employed. If, for example, calcium 
 fluorid or calcium carbonate is present, allowance must be 
 made for them so that sufficient acid will remain to react 
 
204 FERTILIZERS 
 
 properly upon the phosphate. On the other hand, manu- 
 facturers avoid, in so far as possible, the formation of 
 free phosphoric acid, for the reason that the mass is then 
 likely to be moist, to be more difficult to handle, and to be 
 much more destructive to the bags used in its shipment. 
 
 348. The practical process of making superphosphate. — 
 Chamber acid, because of its cheapness, is usually em- 
 ployed instead of purer grades of sulfuric acid. This 
 has a specific gravity of 1.5 to 1.6. The acid and the raw 
 ground phosphate are introduced into a mixer, and the 
 whole mass is then passed into a "den." There the chief 
 reaction follows in the course of a few hours, though the 
 material is usually allowed to react for some days. During 
 this time a very high temperature is developed, often 
 exceeding 100° C, which is highly favorable to the decom- 
 position of the remaining tricalcium phosphate. The 
 gypsum produced, combines with the excess of moisture ; 
 and after a short time the material dries out enough so 
 that it can be readily broken up and brought into a friable 
 and fit condition for use. At present, in certain works, 
 the gases coming from the dens are condensed, the liquors 
 concentrated in lead pipes or chambers, and the compounds 
 of fluorin prepared therefrom are used in enameling por- 
 celain and for other purposes. 
 
 349. Double superphosphate. - — An unusually high grade 
 of superphosphate found on the market in this country 
 and in Europe is the "double " superphosphate. This is 
 made by treatment of low-grade phosphates with an ex- 
 cess of dilute sulfuric acid. By use of filter presses the 
 gypsum and other insoluble impurities are largely separated 
 from the remaining liquid mixture, which consists of sul- 
 furic acid, monocalcium phosphate, and free phosphoric 
 acid. This liquid is then highly concentrated, by evapora- 
 
MANUFACTURED PHOSPHATES 205 
 
 tion, until it is sufficiently strong for use in treating the 
 highest grades of rock phosphates, or until it is of proper 
 strength to be used as a dilutant of ordinary sulfuric acid, 
 employed for that purpose. The reaction of the free 
 phosphoric acid of the solution upon the tricalcium phos- 
 phate is represented by the following equation : — 
 Ca3(P0 4 ) 2 + 4 H3PO4 = 3 CaH 4 (P0 4 ) 2 . 
 
 tricalcium phosphoric double superphos- 
 
 phosphate acid phate (monocalcium 
 
 phosphate) 
 
 By the process described above, the content of monocal- 
 cium phosphate may be raised so that a product contain- 
 ing from 40 to 45 per cent of soluble phosphoric acid is 
 produced. It contains, however, free phosphoric acid in 
 excess and is on this account difficult to dry. It may 
 also prove slightly injurious for a -few days on a very 
 acid soil, if used with plants which are especially sensitive 
 to acidic conditions. 
 
 It is possible by leaching ordinary superphosphate with 
 water, and by evaporation of the solution, to obtain a 
 material with as high as 60 per cent of soluble phosphoric 
 acid. 
 
 High-grade superphosphates are prepared in Europe as 
 a by-product from the manufacture of gelatine. 
 
 The direct manufacture of these high-grade phosphates 
 is economical only where fuel is cheap and where sulfuric 
 acid and low-grade phosphates are available at very low 
 cost ; or where the material must be transported for long 
 distances, as may yet be the case in the United States 
 when the phosphate beds of Florida and Tennessee are 
 exhausted and those of the far West must be drawn upon 
 to supply the needs of the East. 
 
 These high-grade phosphates are often of material 
 
206 FERTILIZERS 
 
 service to the fertilizer manufacturer in the preparation 
 of some of the higher grades of mixed fertilizers, for by 
 their use lower grades of potassium salts or of nitrogenous 
 materials may be employed than would otherwise be pos- 
 sible. (See Fig. 19.) 
 
 350. Dissolved bone. — Raw bone is now seldom 
 treated with sulfuric acid, for the purpose of manufactur- 
 ing dissolved bone, owing to the fact that it yields a 
 sticky, gelatinous mass which it is difficult to handle. 
 
 By steaming, bone becomes friable, and it may then be 
 treated with sulfuric acid without difficulty. Owing to 
 the removal of much of the fat and organic matter by this 
 process, the mass dries out within a few hours after acidula- 
 tion so that it can either be easily ground and utilized 
 directly as a fertilizer, or it may be introduced into mix- 
 tures of other fertilizer materials. 
 
 Dissolved steamed bone necessarily varies somewhat in 
 composition according to the character of the bone used 
 in its manufacture. It may be safe to say that it usually 
 contains from 1 to 3 per cent of nitrogen. It also contains 
 from 15 to 18 per cent of phosphoric acid, the major 
 portion of which is soluble in water. (See Fig. 20.) 
 
 351. Dissolved bone-black. — The waste bone-black 
 from sugar refineries, and the highly carbonized bone 
 residues from annealing processes, yield, upon treatment 
 with sulfuric acid, a superphosphate similar to that from 
 bone, excepting for the fact that it contains little or no 
 nitrogen. 
 
 Towards the close of the preceding century acid phos- 
 phate began to gradually replace dissolved bone-black, 
 but still the prejudice of many farmers was so strong 
 against any fertilizer made from rock that acid phos- 
 phate was dyed black, in some cases, in order that it 
 
MANUFACTURED PHOSPHATES 
 
 207 
 
 
 o> 
 
 -M 
 
 1 s 
 
 4) *S 
 ej 03 
 
 .at 
 
 
 So 
 
208 FERTILIZERS 
 
 might be sold for dissolved bone-black. Dyed acid phos- 
 phate was also introduced into some mixed fertilizers, 
 which had been compounded previously by the use of 
 dissolved bone-black; but as farmers came to under- 
 stand that dark or black fertilizers were not necessarily 
 better than others, the tendency to resort to such meas- 
 ures ceased. (See Fig. 21.) 
 
 352. Laboratory studies on the solubility of phos- 
 phates. — The recent exploitation of raw rock phosphate, 
 as a fertilizer, makes a consideration of the action of cer- 
 tain solvents upon the various phosphates of special inter- 
 est. It must not, however, be forgotten that in the soil 
 many individual factors, including living organisms, are at 
 work ; and many of the chemical and physical conditions 
 are also entirely different from those of the laboratory. 
 Many of the phosphates studied in the laboratory are 
 artificial products. They are in consequence not of the 
 same physical character as certain of the phosphates 
 with which the farmer has to deal. For these reasons 
 great care should be taken in attempting to apply all such 
 laboratory findings to the conditions practically met with 
 in the field. 
 
 With this precautionary introduction it may be well to 
 consider certain laboratory observations, which may have 
 a direct, or, more frequently, indirect, bearing upon the 
 practical utilization of phosphates. 
 
 353. The action of water on monocalcium phosphate. — 
 As concerns the action of water upon monocalcium 
 phosphate there exist widely divergent statements. 
 These differences are believed to be due to the fact that 
 some of the monocalcium phosphate employed by the 
 different experimenters contained a little free phosphoric 
 acid, which increased its solubility ; furthermore, owing 
 
MANUFACTURED PHOSPHATES 
 
 209 
 
210 FERTILIZERS 
 
 to the hygroscopic nature of the free acid, and to the water 
 therefore absorbed, the amount of actual monocalcium 
 phosphate employed may sometimes have been less than 
 was supposed. 
 
 From recent investigations it also appears that upon 
 the addition of water to monocalcium phosphate a cer- 
 tain amount of hydrated dicalcium phosphate (CAHPO4 
 • 2 H 2 0) is formed, and at still higher temperatures even 
 the anhydrous salt (CaHP0 4 ), which, unlike the hydrated 
 salt, is insoluble in citric acid. At the same time the 
 resulting solution contains a higher ratio of phosphoric 
 acid to lime, than the monocalcium phosphate. This 
 is indicated partially by the equation which follows : — 
 
 CaH 4 (P0 4 ) 2 - H 2 + H 2 = GaHP0 4 + 2H 2 + H 3 P0 4 - 
 
 The free phosphoric acid therefore carries with it into the 
 solution some dicalcium phosphate. The addition of 
 more water results in changing relatively more of the 
 monocalcium phosphate into free phosphoric acid and 
 dicalcium phosphate, whereas the addition of phosphoric 
 acid to the solution renders more of the dicalcium phos- 
 phate soluble. 
 
 Experiments by Joly l have shown that the addition 
 of monocalcium phosphate to a given amount of water 
 resulted, up to certain limits, in a marked increase in the 
 free phosphoric acid in solution ; but at the temperature 
 at which he worked, the addition of an excess of monocal- 
 cium phosphate beyond 65 grams to 100 grams of water, 
 resulted in no further decomposition of the salt nor in 
 further change in the composition of the solution. 
 
 Under this last condition there are, according to Cam- 
 
 1 Compt. rend., 97 (1883), 1480. 
 
MANUFACTUBED PHOSPHATES 211 
 
 eron, two solid phases, viz. monocalcium and dicalcium 
 phosphate. 
 
 It has been shown by Cameron and Seidell l at a tem- 
 perature of 25° C, that when both the monocalcium phos- 
 phate and dicalcium phosphate are present as solid phases, 
 the amount of " free " phosphoric acid (P 2 5 ) was 120 
 grams, per liter of solution. 
 
 354. The action of water on dicalcium phosphate. — 
 When water is added to dicalcium phosphate, there is 
 produced on the one hand a solution, and on the other 
 an amorphous solid containing a greater ratio of lime to 
 phosphoric acid than is present in the dicalcium phos- 
 phate. This solid was formerly regarded as tricalcium 
 phosphate. 
 
 It has been shown by Millot and confirmed by Viard 2 
 that when dicalcium phosphate is acted upon by boiling 
 water, free phosphoric acid and some lime go into solution, 
 whereas the solid phase is composed of amorphous tri- 
 calcium phosphate and anhydrous dicalcium phosphate. 
 It was supposed by certain investigators, however, that 
 the solid was tricalcium phosphate and that monocalcium 
 phosphate resulted, which passed into solution. Definite 
 formulas have been ascribed by some investigators to the 
 solid compounds resulting from treating dicalcium phos- 
 phate with water, under the assumption that they were 
 dealing with a distinct compound rather than with a mix- 
 ture of two solid phases, or with a series of solid solutions. 
 That the latter was probably the case has been shown by 
 Rindell, who insured final conditions of equilibrium by 
 determining at intervals the electrical conductivity of the 
 solutions with which he worked. 
 
 1 Jour. Am. Chem. Soc, 27 (1905), 1503. 
 
 2 Compt. rend., 127 (1898), 178. 
 
212 FERTILIZERS 
 
 It has been shown recently by Buch J that after subject- 
 ing dicalcium phosphate to fifty-three successive teachings 
 with water, it had been transformed completely into tri- 
 calcium phosphate ; and he suggests the possibility of 
 carrying the transformation still further, in view of the 
 basic compounds of phosphoric acid which are known to 
 exist in nature. 
 
 The solubility increased by carbonic acid. — The solu- 
 bility of dicalcium phosphate has been shown by Dusart 
 and Pelouze 2 to be more than two and one-fourth times as 
 great in water saturated with carbon dioxid as in pure 
 water ; and Cameron and Seidell found that solid gypsum 
 increased the solvent action of water saturated with carbon 
 dioxid. 
 
 355.. The action of water on tricalcium phosphate. — 
 In connection with a study of tricalcium phosphate, it 
 was found unstable when brought in direct contact with 
 water, and it yielded a solution having a higher ratio of 
 phosphoric acid to lime than was possessed by the original 
 phosphate. At the same time a phosphate with increas- 
 ing basicity is produced which, according to Cameron and 
 Bell, 3 also " becomes decreasingiy soluble on repeated 
 treatment with water." According to the same authorities 
 the soil water, containing both mineral and organic mat- 
 ter, doubtless exerts a much greater solvent action on 
 the phosphoric acid of the tricalcium phosphate than is 
 exerted by pure water. 
 
 If the first work is right, it appears to offer a partial ex- 
 planation of the long-continued after-effects which follow 
 the application of superphosphates to soils, for by the 
 
 *Zeits. anorg. Chem., 52 (1907), 325. 
 
 2 Compt. rend., 66 (1868), 1327 ; cited from Cameron and Bell. 
 
 3 Bvil. 41, Bureau of Soils, U. S. Dept. of Agr. (1907). 
 
MANUFACTURED PHOSPHATES 213 
 
 reaction of the monocalcium phosphate with such basic 
 phosphates as may be present therein, the basicity of the 
 latter should become less, and much of the phosphoric acid 
 would consequently remain, for a considerable period, much 
 more readily soluble than that present at the outset in the 
 original basic phosphate. 
 
 It appears from what has preceded that what is gener- 
 ally spoken of as tricalcium phosphate cannot be considered 
 as a definite chemical compound, in all cases, but rather, 
 in most instances, as one of a series of solid solutions of 
 lime and phosphoric acid. 
 
 The solubility increased by carbonic acid. — It has been 
 shown by many experimenters that tricalcium phosphate 
 is more soluble in water containing carbon dioxid than it 
 is in pure water. 
 
 A number of determinations were made by Schloesing 1 
 of the solubility of a phosphate which, by analysis, was 
 shown to be very close to a tricalcium phosphate. The 
 results secured by treating a gram of the phosphate for a 
 day at 16° to 20° C. with 1250 c.c. of solvent, were found 
 to be as shown on the following page. 
 
 The table shows the great influence of carbon dioxid on 
 the solubility of such phosphate, and the low solubility of 
 the phosphoric acid, in all cases, in the presence of large 
 amounts of calcium carbonate. This action of calcium 
 carbonate and of other calcium salts in depressing the 
 solubility of tricalcium phosphate, even in the presence of 
 carbon dioxid, has been suggested as being due possibly to 
 the formation of a common ion (Ca) which lessens the 
 quantity of phosphoric acid which passes into solution. 
 On this basis potassium chloric! would be expected to have 
 a solvent action upon tricalcium phosphate, and this has 
 
 iCompt. rend., 131 (1900), 149. 
 
214 
 
 FERTILIZERS 
 
 Solvent 
 
 P2O5 PER 
 
 Liter. 
 Milligrams 
 
 CaO per 
 Liter. 
 Milli- 
 grams 
 
 Water 
 
 0.74 
 
 6.90 
 
 48.50 
 91.90 
 
 0.38 
 
 1.10 
 
 0.80 
 
 1.77 
 
 1.30 
 
 
 1200 c.c. distilled water and 50 e.c. water 
 
 saturated with CO2 
 
 1000 c.c. distilled water and 250 c.c. water 
 
 1250 c.c. water saturated with C0 2 . . 
 Water containing 174 mmg. of CaC0 3 . 
 
 and 82 mmg. of C0 2 per liter . . . 
 Water containing 290 mmg. of CaC0 3 
 
 and 171 mmg. of C0 2 per liter . . . 
 Water containing* 389 mmg. of CaC0 3 
 
 and 270 mmg. of C0 2 per liter . . . 
 Water containing 488 mmg. of CaC0 3 
 
 and 415 mmg. of C0 2 per liter . . . 
 Water containing 558 mmg. of CaC0 3 
 
 and 541 mmg. of C0 2 per liter . . 
 
 100 
 162 
 219 
 273 
 313 
 
 been shown by Cameron and Hurst to be the case ; though 
 they found that it also had a decomposing action, as would 
 reasonably be expected. 
 
 The solubility and decomposability increased by certain 
 substances. — Sodium nitrate, sodium chlorid, and solu- 
 tions of gelatine, sugar, and albumin have all been shown 
 to have a solvent, and in some cases also a decomposing 
 action on tricalcium phosphate. 
 
 356. Determination of " soluble " phosphoric acid. — 
 In the analysis of commercial fertilizers the first step in 
 the determination of phosphoric acid is to place a weighed 
 portion of the material on a filter paper, and then to leach 
 it with water. By this operation practically all of the 
 monocalcium phosphate (CaH 4 (P0 4 ) 2 ) is dissolved, and 
 other changes in associated phosphates, as suggested 
 previously, occur to a slight extent. The quantity of the 
 
MANUFACTURED PHOSPHATES 215 
 
 dissolved " phosphoric acid " is determined and reported 
 as " soluble " phosphoric acid (phosphorus pentoxid 
 P 2 5 ). 
 
 357. Advantages of soluble phosphoric acid. — One 
 advantage of monocalcium phosphate over other phos- 
 phates is due to the fact that it is readily dissolved by 
 water ; and if applied as a top-dressing it is easily carried 
 into the soil. If incorporated with the soil at the outset, 
 it also becomes more generally distributed, as the result 
 of subsequent rainfalls, than would be the case if the 
 phosphate were introduced in an insoluble state. 
 
 358. The reversion of monocalcium phosphate. — It 
 is well known that the monocalcium phosphate after 
 entering the soil, passes at once, or very quickly, in the 
 presence of considerable moisture, into less soluble com- 
 binations. Indeed solutions of monocalcium phosphate, 
 if simply heated, or if allowed to stand for some time at 
 ordinary temperatures, break up into dicalcium phosphate 
 and phosphoric acid as follows : — 
 
 CaH 4 (P0 4 ) 2 = CaHP0 4 + H 3 P0 4 . 
 
 monocalcium dicalcium phosphoric 
 
 phosphate phosphate acid 
 
 This change takes place to some extent even in the dry- 
 ing of superphosphate in the factory. This is especially 
 true of superphosphate made from Florida phosphates, 
 and from such other phosphates as yield a rather moist 
 product. 
 
 If the soil contains calcium carbonate, a considerable 
 part of the monocalcium phosphate is supposed to react 
 with it to produce essentially tricalcium phosphate, as 
 follows : — 
 
210 FERTILIZERS 
 
 CaH 4 (P0 4 )2 + 2 CaC0 3 = Ca 3 (P0 4 ) 2 + H 2 0. 
 
 raonocalcium calcium tricalcium water 
 
 phosphate carbonate phosphate 
 
 It is supposedly for this reason, in part, that on acid 
 soils the application of lime coincidently with, or prior 
 to, the application of monocalcium phosphate, is desira- 
 ble ; for otherwise far more of the monocalcium phos- 
 phate would presumably react with iron and aluminum 
 oxids and hence become subsequently less available to 
 plants than the finely divided and newly formed trical- 
 cium phosphate. 
 
 359. Liming after reversion with iron and aluminum 
 oxids. — In case superphosphates have been applied 
 sucessively to soils rich in iron and aluminum oxids and 
 poor in calcium carbonate, the proper course, if one wishes 
 to render the phosphoric acid available, is to lime the land 
 quite heavily ; for, as has been pointed out by Deherain in 
 France, such a procedure is followed by the transformation 
 of much of the unavailable phosphoric acid into calcium 
 combinations which can be more readily utilized by plants. 
 Similar remarkable effects of lime in rendering the phos- 
 phorus compounds of the soil available to plants, or at 
 least in rendering the application of phosphates no longer 
 necessary, have been observed at the experiment station of 
 the Rhode Island State College in connection with a soil 
 which had received no phosphates for at least a dozen 
 years. Similar marked benefit from liming also resulted 
 on soil to which roasted aluminum phosphate (con- 
 taining some iron phosphate) had been applied. Indeed, 
 this benefit from liming in the latter case continued for 
 several years after the last application of the lime and of 
 the aluminum phosphate was made. A similar effect 
 of applying lime was in some cases either entirely lacking, 
 
MANUFACTURED PHOSPHATES 217 
 
 or it was far less striking, in connection with the use of 
 the unroasted aluminum phosphate. 
 
 360. The determination of " reverted " phosphoric 
 acid. — After a sample of fertilizer has been leached with 
 water, in the regular course of analysis, it is again extracted 
 under definite conditions by digestion for one-half hour 
 with a neutral solution of ammonium citrate. This treat- 
 ment readily brings into solution phosphoric acid present 
 as dicalcium phosphate (CaHP0 4 ), regardless of whether 
 it was formed by the reversion of monocalcium phosphate 
 or otherwise. 
 
 361. " Reverted " phosphoric acid not all from dical- 
 cium phosphate. — In addition to dicalcium phosphate 
 there is also dissolved by this treatment about one-half 
 of the phosphoric acid which is present in steamed bone 
 tankage, and a considerably less proportion of that in 
 steamed bone. The ammonium citrate solution also dis- 
 solves to a great extent the phosphoric acid present in 
 roasted iron and aluminum phosphates. 
 
 Since the term " reverted " is applied to all of the phos- 
 phoric acid removed by the extraction with ammonium 
 citrate solution, it is evident that the so-called reverted 
 phosphoric acid may be derived from dicalcium phosphate, 
 tricalcium phosphate, and even from iron and aluminum 
 phosphates. It is obvious, therefore, that its value to the 
 farmer is likely to be variable, and conditioned not only 
 upon its source, but in some cases even upon whether it is 
 used on soils which are acid or upon those which are well 
 supplied with carbonate of lime. 
 
 362. The term "available" phosphoric acid. —Avail- 
 able phosphoric acid is the term applied to the sum of 
 the soluble and reverted phosphoric acid, determined 
 as just described. It is therefore a trade term, rather 
 
218 ' FERTILIZERS 
 
 than one always strictly indicative of its agricultural 
 value. 
 
 363. Insoluble phosphoric acid. — The phosphoric acid 
 remaining undissolved after the successive extractions with 
 water and ammonium citrate solution is finally deter- 
 mined and designated " insoluble " phosphoric acid. If 
 such phosphoric acid is present in bone and in bone tank- 
 age, it will have a materially higher crop-producing value 
 than if it is present in mineral tricalcium phosphate. If 
 in this latter form, it will likewise be more readily available 
 to plants than if present in powdered apatite or in the 
 unroasted phosphates of iron and aluminum. It is ob- 
 vious, therefore, that the mere analytical statement may 
 fail, in certain particulars, to give complete information 
 concerning the probable fertilizing value of the insoluble, 
 as well as of the reverted, phosphoric acid. As concerns 
 the soluble phosphoric acid, on the contrary, it is equally 
 valuable, regardless of the source from which it may have 
 been derived. 
 
 364. The reversion of monocalcium phosphate. — In 
 addition to the reversion of monocalcium phosphate 
 to dicalcium phosphate, and finally to tricalcium phos- 
 phate, when brought together with calcium carbonate, 
 monocalcium phosphate may react upon tricalcium 
 phosphate, in the presence of moisture, in such a way 
 that, for many months after a fertilizer is mixed, the 
 soluble and the insoluble phosphoric acid become grad- 
 ually less and the reverted phosphoric acid increases 
 correspondingly. This reaction may be expressed as 
 follows : — 
 
 Ca 3 (P0 4 ) 2 + CaH 4 (P0 4 ) 2 = 4 CaHP0 4 . 
 
 tricalcium monocalcium dicalcium 
 
 phosphate phosphate phosphate 
 
MANUFACTURED PHOSPHATES 219 
 
 365. Reversion often beneficial in some respects. — 
 Such a reaction, though beneficial from the standpoint of 
 the availability of the phosphoric acid present originally in 
 the insoluble tricalcium phosphate, lessens the value, at 
 least for top-dressing, of the phosphoric acid present at 
 the outset in the " soluble " state. Owing to the con- 
 siderable amount of water involved in the formation of the 
 hydrous salt which s produced (CaHP0 4 • 2 H 2 0), the rate 
 of the reaction in fertilizers in storage is determined in 
 part by the rate at which water can be absorbed from the 
 air, although in the soil this change would be very rapid. 
 
 366. Reversion with iron and aluminum oxids serious. 
 — The most serious form of reversion which may result 
 in a superphosphate in the soil, is that which takes place 
 when monocalcium phosphate reacts upon iron and 
 aluminum oxids or upon sulfates of these elements. The 
 first of these reactions maybe suggested by the following : — ■ 
 
 2 Fe 2 (OH) 6 + 3 CaH 4 (P0 4 ) 2 = 2 Fe 2 (P0 4 ) 2 + Ca 3 (P0 4 ) 2 4- 
 
 ferric monocalcium ferric tricalcium 
 
 hydrate phosphate phosphate phosphate 
 
 12 H 2 0. 
 
 water 
 
 The tricalcium phosphate produced in this case can 
 react upon further quantities of monocalcium phosphate 
 to cause additional reversion. 
 
 It is well understood that the presence of iron oxid, in 
 excess of 2 per cent, in phosphates intended for super- 
 phosphate manufacture, is objectionable, and that 
 above 4 per cent is prohibitive. This is due to the fact 
 that the oxid is dissolved by the sulfuric acid, and thus 
 the way is paved for the more rapid subsequent reversion 
 of the phosphoric acid. This is a most serious form of 
 reversion because of the low availability of the iron phos- 
 
220 FERTILIZERS 
 
 phate produced, especially under unfavorable soil condi- 
 tions. 
 
 The reaction just referred to is a reversible one, as 
 indicated below : — 
 
 3 FeP0 4 + 3 H 2 S0 4 ^± (FeP0 4 -2 H 3 P0 4 ) + Fe 2 (S0 4 ) 3 . 
 However, in the presence of an excess of sulfuric acid, it 
 proceeds as follows : — 
 
 2 FeP0 4 + 3 H 2 S0 4 ^1 2 H 3 P0 4 + Fe 2 (S0 4 ) 3 . 
 The reaction of such compounds with monocalcium phos- 
 phate is shown by the following : — ■ 
 Fe 2 (S0 4 ) 3 + CaH 4 (P0 4 ) 2 = 2 FeP0 4 + CaS0 4 + 2 H 2 S0 4 . 
 
 Notwithstanding that this reaction is probably never 
 complete, a great amount of insoluble ferric phosphate is 
 nevertheless formed. The sulfuric acid set free might 
 then unite with more iron, and thus the process could be 
 repeated until equilibrium is finally established. 
 
 Reactions are possible with aluminum compounds, 
 similar to those described above for ferric oxid and for 
 ferric sulfate. 
 
 In case ferrous oxid were present, instead of the ferric 
 oxid, a possible reaction has been suggested as follows : — ■ 
 
 4 FeS0 4 + 20 + CaH 4 (P0 4 ) 2 + 3 Ca(P0 4 ) 2 
 
 ferrous oxy- monocalcium tricalcium 
 
 sulfate gen phosphate phosphate 
 
 = 4 FeP0 4 + 4 CaS0 4 + 2 H 2 
 
 ferric calcium water 
 
 phosphate sulfate 
 
 According to Schucht, however, who demonstrated 
 the matter experimentally, the reaction takes the follow- 
 ing course : CaH 4 (P0 4 ) 2 • H 2 + Fe 2 (S0 4 ) 3 + 5 H 2 = 
 FeP0 4 • 2 H 2 + CaS0 4 • 2 H 2 + 2 H 2 S0 4 ; then, H 2 S0 4 
 4- CaH 4 (P0 4 ) 2 • H 2 = CaS0 4 -2 H 2 4- 2 H 3 P0 4 ; and, 
 
MANUFACTURED PHOSPHATES 221 
 
 finally, 2 (FeP0 4 • 2 H 2 0) + 4 H 3 P0 4 = 2 (FeP0 4 • 2 H 3 P0 4 ) 
 + 4 H 2 0. In fact, the hydrated iron phosphate may, in 
 the superphosphate, become wholly insoluble again, as 
 shown below : — 
 
 FeP0 4 • 2 H 2 + CaS0 4 = CaS0 4 • 2 H 2 + FeP0 4 . 
 
 It is for the foregoing reasons that the Redonda and 
 other iron and aluminum phosphates cannot be utilized 
 for superphosphate manufacture, and hence are roasted, 
 or subjected to certain other chemical treatment, as a 
 means of increasing their availability. 
 
 367. Reversion as affected by pyrite. — The presence 
 in phosphates of small amounts of pyrite (FeS 2 ) and of 
 silicates of iron and aluminum is sometimes unobjection- 
 able from the standpoint of the superphosphate manu- 
 facturer, for the reason that they are usually but partly 
 soluble in sulfuric acid and do not react with monocalcium 
 phosphate. Nevertheless, the solvent action of these 
 substances does not always hinge upon sulfuric acid only, 
 for the hydrofluoric acid liberated from the calcium fluorid, 
 often present in superphosphates, readily decomposes 
 silicates. Under certain conditions aluminum silicate in 
 considerable amounts may therefore eventually cause 
 reversion of the phosphoric acid. 
 
 368. The fixation of superphosphates in soils rapid. — 
 Many experiments have been conducted with soils, em- 
 bracing those which are highly calcareous, sandy, and 
 clayey, also with and without admixtures of precipitated 
 calcium carbonate, marl, oxids of iron and alumina, in 
 order to ascertain the rapidity of the fixation of soluble 
 phosphoric acid. In many of these laboratory experi- 
 ments, as, for example, in one by Schroeder in which two 
 parts by weight of superphosphates were used with eight 
 
222 ' FERTILIZERS 
 
 parts of loam, the proportions between superphosphate 
 and soil were entirely unlike those existing in the field, for 
 in actual practice only from 200 to 1200 pounds of super- 
 phosphate are usually applied per acre, representing a 
 depth of from six to ten inches of soil. Notwithstanding, 
 therefore, that in the former case only a trifle over half 
 of the phosphoric acid was fixed at the end of twenty 
 days, the usual application in the field might, under favor- 
 able conditions of rainfall, have been fixed in a single 
 day. In fact, a great preponderance of evidence supports 
 the idea that very rapid fixation of soluble phosphoric 
 acid takes place under the usual conditions of farm prac- 
 tice, provided the rainfall is sufficient to largely dissolve 
 and distribute the monocalcium phosphate; and that 
 losses by leaching are small. In times of drought, how- 
 ever, particles of superphosphate which have lain for a 
 considerable period in the soil have been found to still 
 contain soluble phosphoric acid. 
 
 369. The fixation of phosphates confined chiefly to 
 the surface soil. — Upon examining the soil of the Broad- 
 balk wheat field at the Rothamsted experiment station 
 in England, Dyer found that notwithstanding the fifty 
 annual applications of 350 pounds per acre of high-grade 
 superphosphate, the subsoil from a depth of nine inches 
 downward contained practically no more phosphoric acid 
 removable by a 1 per cent citric acid solution than where 
 none had been applied. Nevertheless, the upper nine 
 inches of soil showed that it had been enormously enriched 
 by phosphoric acid which the citric acid solution was 
 capable of extracting. It must be evident in this case 
 that if the fixation had not been very rapid, much of the 
 phosphoric acid must have been washed into and fixed 
 by the subsoil. 
 
MANUFACTURED PHOSPHATES 223 
 
 The analysis of the drainage waters at Rothamsted has 
 shown but a trifling loss of phosphoric acid, which further 
 supports the foregoing conclusion. 
 
 370. The availability of fixed phosphates may still be 
 high. — It has been found at the Rothamsted station 
 that five or six successive extractions of the soil with the 
 citric acid solution bring it to a state where subsequent 
 extractions fail to yield materially more than was remov- 
 able from the original soil phosphates. The sum of the 
 amounts of phosphoric acid removed in the first five 
 extractions, added to that taken out by the crops of the 
 fifty years, also agrees very closely with the quantity 
 added during the interval, in superphosphates. In this 
 particular case the efficiency of the stored-up phosphate 
 was doubtless greatly enhanced by the presence in the soil, 
 during the interval, of considerable quantities of carbonate 
 of lime. Under this condition less phosphoric acid prob- 
 ably entered into combination with iron and alumina than 
 would otherwise have been the case. See Fig. 22. 
 
 371. Injury from applications of superphosphate rare. — 
 If superphosphates are applied a short time before plant- 
 ing, there is no likelihood of their causing injury to the 
 crops. A striking instance of injury to oats, when ap- 
 plied just before seeding, was noticed upon an unlimed acid 
 soil at the experiment station of the Rhode Island State 
 College, in the case of double superphosphate, although 
 it was not observable with any of the other superphos- 
 phates which were used. This ill effect, however, which 
 was indicated by the unhealthy appearance and blanching 
 of the tips of the leaves, finally disappeared within an 
 interval of only a few days, probably after the initial 
 acidity had been reduced, by the soil reactions, below the 
 critical point for that particular plant. 
 
224 
 
 FERTILIZERS 
 
MANUFACTURED PHOSPHATES 225 
 
 372. Soils on which superphosphates may give poor 
 results. — It has been found on the acid peat soils of 
 Germany (Hochmoor) that the first application of acid 
 phosphate often has little effect and that the use of dical- 
 cium phosphate, bone, basic slag meal, or even of certain 
 unacidulated mineral phosphates is followed by better 
 results. On such soils, as well as on those which are light 
 and sandy and more or less acid, the use of acid phosphate 
 is not likely to be followed by the best possible results, 
 unless they have first been limed. 
 
 373. Superphosphates have a flocculating action on 
 soils. — In experiments by Sachsse and Becker 1 it was 
 shown that superphosphate has a greater flocculating 
 effect upon clayey particles of soils than either gypsum 
 or lime. It should therefore improve their tilth and their 
 ability to hold and to deliver water properly to the plant. 
 Superphosphate is recognized as improving, in this par- 
 ticular, such soils as have been made alkaline by long use 
 of nitrate of soda. 
 
 374. Various soil conditions affecting the choice of 
 phosphate to be used. — It has often been reported that 
 on the highly calcareous soils of Norfolk, England, where 
 fine bone meal was of little value, superphosphates were 
 found to act splendidly on the turnip crop ; for they not 
 only encouraged immediate and vigorous growth, but 
 pushed the plants along so fast that they very largely 
 escaped injury from the turnip fly. 
 
 Acid soils of every kind are not as a rule ideally 
 adapted to superphosphates unless they have first re- 
 ceived applications of wood-ashes, or lime in some suit- 
 able form. 
 
 On all ordinary soils, superphosphates are especially 
 
 1 Die landw. Vers.-Sta., 43 (1894), 22. Cited from E. S. R., 5, 696. 
 Q 
 
226 FERTILIZERS 
 
 effective, and, contrary to a somewhat common idea, 
 the after-effects from their use are long continued. 
 
 Notwithstanding that superphosphate acts well on 
 certain highly calcareous soils, Petermann recommends 
 especially for them the dicalcium phosphate, which is 
 not only easily dissolved by carbonic acid, but is also 
 readily drawn upon by plants, by virtue of the direct 
 action of their roots upon the phosphate. 
 
 375. Crops and conditions for which superphosphates 
 are especially adapted. — Many experiments in Europe, 
 supported by results in this country, show that few if 
 any plants respond more quickly or more favorably to 
 superphosphates than the turnip. Coming in the same 
 category close behind the turnip may be mentioned the 
 cabbage and the other closely related plants such as 
 Brussels sprouts, kale, kohl-rabi, and cauliflower, also 
 many of the quickly maturing garden crops, such as 
 lettuce, beets, spinach, and radish. 
 
 Superphosphates are especially adapted to all cases 
 where spring top-dressing is practiced, as, for example, 
 on grass land, for clovers, alfalfa, and winter grains. 
 
 Certain writers for the agricultural press recommend, 
 on the contrary, for such purposes basic slag meal and 
 fine bone meal ; yet it not infrequently happens that the 
 rainfall is light after the spring applications have been 
 made ; and instances have occurred where, for several 
 weeks after the fertilizer was applied, hardly more than 
 one-fourth of an inch of rain has fallen. Under such 
 circumstances grass crops have been increased from two 
 to two and one-half tons per acre by the top-dressings, in 
 which acid phosphate was used, whereas if the phosphoric 
 acid had been applied in bone or in basic slag meal, it 
 would have been practically without effect on the grass 
 
MANUFACTURED PHOSPHATES 227 
 
 crop of that season. Indeed, the consequences which 
 must follow in such cases, if phosphates insoluble in water 
 are used, are too obvious to require further illustration. 
 
 The use of liberal amounts of superphosphates, es- 
 pecially in conjunction with generous applications of nitrog- 
 enous and potassic fertilizers, has been found to be es- 
 pecially helpful in connection with the culture of the sugar 
 beet ; for by their use the maturity is hastened and the 
 sugar content consequently increased. Similarly, the use 
 of extra superphosphate for potatoes not only often in- 
 creases the total crop, but also the percentage of starch, 
 due chiefly to the hastening of maturity. The use of 
 superphosphate is also helpful in some cases because by 
 hastening maturity the crops may more surely escape frost. 
 
 Recent studies have shown that superphosphates aid the 
 germination of seeds to a remarkable degree, as compared 
 with other fertilizer ingredients. 
 
CHAPTER XVII 
 
 POTASSIC FERTILIZERS 
 
 In earlier times wood-ashes and the ashes of sea-weeds 
 were the chief sources of potash, but at present the sup- 
 plies for the entire world are practically all drawn from the 
 German mines. 
 
 376. Wood-ashes and lime-kiln ashes. — Wood-ashes 
 constitute one of the most ancient sources of potash, not 
 only for industrial purposes, but also for use as a fertilizer. 
 They may contain from 2.5 to 12 per cent or more of potash 
 (potassium oxid, K 2 0), dependent upon the temperature 
 of the fire, the kind of wood used, and the freedom from 
 impurities. As offered for sale in the United States, at 
 present, the potash content usually ranges from 3 to 8 per 
 cent. In addition, they contain from 30 to 35 per cent of 
 calcium oxid, 3 to 4 per cent of magnesium oxid, and from 
 1 to 2.5 per cent of phosphoric acid, together with im- 
 purities and other ingredients of little or no fertilizing 
 value. 
 
 Leached wood-ashes contain usually but from 0.3 to 1 
 per cent of potash, the quantity depending upon the 
 thoroughness of the leaching. 
 
 Lime-kiln ashes, which consist of a mixture of waste 
 lime and wood-ashes or coal-ashes, rarely contain more 
 than from 1 to 2 per cent of potash. 
 
 377. Cotton-seed hull ashes. — A prominent source of 
 potash, used very extensively at an earlier date for the 
 growing of tobacco in the Connecticut Valley, was the 
 
 228 
 
POTASSIC FERTILIZERS 229 
 
 ashes produced in the burning of cotton hulls, known in 
 the trade as " cotton-seed hull ashes." In the analysis 
 of forty samples at the Massachusetts agricultural experi- 
 ment station the potash content was found to range from 
 10 to 42 per cent, the average being 22.48 per cent ; they 
 also contain from 3 to 13 per cent of phosphoric acid, about 
 9 per cent of lime, and 10 per cent of magnesia. It is 
 obvious that material ranging so widely in potash content 
 should be bought only by analysis or on a definite guaranty. 
 
 378. Saltpeter waste. — A by-product known as salt- 
 peter waste has been found by the Massachusetts experi- 
 ment station to range in potash content from 5.6 to 13.7 
 per cent. The chlorin present amounted to 4.6 per cent, 
 the sodium oxid to 37 per cent, and the nitrogen to from 
 0.52 to 3.3 per cent. 
 
 This material, like all factory by-products, can be bought 
 with safety only on analysis. 
 
 379. Other wastes containing potash. — In addition 
 to the foregoing, there are a vast number of other waste 
 products, including prussiates, cyanid residues, and brick- 
 kiln ashes, which are used for manurial purposes; but 
 they usually contain widely variable percentages of potash, 
 and some of them sometimes contain objectionable sub- 
 stances ; for this reason they hardly deserve further men- 
 tion in this connection. 
 
 380. Potash from sea-weeds and other plants. — 
 Among the plants which serve as prominent sources of 
 potash along the sea-coast, may be mentioned the marine 
 algae familiarly known as " sea-weeds." Incidentally 
 unusual interest has just been aroused in the recovery of 
 potash from sea-weeds, chiefly on account of difficulties 
 with the German potash producers, due to contracts made 
 between the owners of certain individual German mines 
 
230 
 
 FERTILIZERS 
 
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POTASSIC FERTILIZERS 
 
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232 FERTILIZERS 
 
 and certain groups of American fertilizer manufacturers. 
 It has, in consequence, been again proposed to make use 
 of the enormous masses of sea-weeds available on the Pacific 
 coast. This is no new idea, for sea-weeds have been thus 
 utilized in the past, and even certain salworts (Salsola) 
 have been expressly cultivated, collected, and burned in 
 Spain, Sicily, and elsewhere, and the fused ashes sold 
 under the trade name of " barilla." Ashes of these plants 
 from near the Caspian Sea are said to contain 5 per cent 
 of potash which is readily soluble in water. 
 
 In earlier times straw and weeds of various kinds were 
 used for the manufacture of both sodium and potassium 
 carbonates. At various times it has been proposed to 
 utilize for this purpose wormwood, tansy, the common 
 marigold, and other plants rich in alkalies. 
 
 381. Analyses of sea-weeds. — Many analyses of 
 sea-weeds common on the New England coast have been 
 made by Wheeler and Hart well, 1 and these, with analyses 
 by others, are given in the tables on pages 230 and 231. 
 
 382. Tobacco stems. — Tobacco stalks and the waste 
 midribs from the leaves are often sold as " tobacco stems." 
 The Massachusetts agricultural experiment station re- 
 ports six analyses of such material showing the potash 
 content to range from 3.76 to 8.82 per cent. With a 
 moisture content of 10.6 per cent, the average potash per- 
 centage was found to be 6.44. Such tobacco stems are also 
 rich in nitrogen besides containing small quantities of 
 lime and magnesia. The potash present in the dried 
 stems may be very largely removed by mere extraction 
 with water, and even the insoluble potash residue must, 
 in the process of decomposition, become very readily 
 available to plants. 
 
 1 Bui. 21, R. I. Agr. Exp. Sta., January, 1893. 
 
POTASSIC FERTILIZERS 233 
 
 383. Indian corn cobs. — It has been shown that In- 
 dian corn cobs contain an average of about 6.8 per cent of 
 potash and that the ashes made from them contain about 
 50 per cent of potash, 1 hence the ashes of corn cobs have a 
 greater total fertilizing value, per ton, than muriate of 
 potash or the high-grade sulfate of potash. 
 
 384. Potassium nitrate. — One of the oldest and best 
 known sources of potash, until the discovery of the Ger- 
 man potash deposits, was "niter," or potassium nitrate. 
 This material usually contains from 12 to 14.5 per cent of 
 nitrogen, in addition to 44.5 to 45.5 per cent of potash. 
 
 Potassium nitrate is especially valuable for agricultural 
 purposes wherever it is desirable to avoid the sulfuric 
 acid and chlorin which are present in the German potash 
 salts. Unfortunately, the supply is so limited, and the 
 price in consequence so high, that it only occasionally 
 comes into close competition with the German potash 
 salts and the Chilian nitrate of soda. Nevertheless, there 
 have been several years during the last two decades when 
 the American farmer might have effected a decided saving 
 in the purchase of his fertilizer supply had he bought 
 potassium nitrate instead of the usual potash salts and 
 nitrate of soda. 
 
 A discussion of the methods used in the manufacture of 
 potassium nitrate are to be found elsewhere (Section 241). 
 
 385. Potassium carbonate. — In the Caucasus there 
 exist many factories for the manufacture of potassium 
 carbonate, which is sold on the basis of 90 per cent of pure 
 potassium carbonate. The chief impurities are sodium 
 carbonate, 5 per cent; potassium sulfate, 2 per cent; 
 and potassium chlorid, 6.5 per cent. In 1906 eleven such 
 factories were reported in Russia. This material, like 
 
 1 E. S. R., 17 (1905-1906), 1054. 
 
234 ' FERTILIZERS 
 
 potassium nitrate, is also to be recommended whenever 
 chlorids and sulfates must be avoided ; but it is more 
 applicable to soils of an acidic character than to those 
 well supplied with basic ingredients. If used in large 
 quantities, it has a tendency to dissolve humus and to 
 bring about deflocculation of the mineral matter, and 
 consequently its use on certain soils may be disadvan- 
 tageous. 
 
 386. History of the German potash deposits. — The 
 German potash salts, which to-day constitute one of the 
 most valuable possessions of any country of the world, 
 were at the outset looked upon as a hindrance in the pro- 
 duction of common salt. 
 
 Salt works had already existed in Stassfurt, Germany, 
 for a long period of time. They were at first the prop- 
 erty of the Duke of Anhalt, they then passed into other 
 hands, and in 1796 were sold to the Prussian " Fiscus." 
 In the years from 1830 to 1840 common salt was discovered 
 by borings made south of the Harz Mountains, in the 
 Thuringian basin. The brines there were so favorable for 
 the manufacture of salt that the weak brine at Stassfurt 
 could not be used in successful competition with them, and 
 hence the Stassfurt works were finally closed in 1860. 
 
 On April 3, 1839, a boring was begun at Stassfurt, and in 
 1843 at a depth of 256 meters the upper covering of the 
 salts was met. It was then continued for 325 meters in 
 the salt, without reaching the bottom of the deposit. The 
 result of this undertaking was entirely unexpected, as 
 well as a great disappointment at the outset, for instead 
 of securing a saturated solution of common salt the saline 
 solutions also contained large amounts of magnesium 
 chlorid and potassium chlorid. It was concluded, how- 
 ever, by Doctor Karsten and Professor Marchand that 
 
POTASSIC FERTILIZERS 235 
 
 at greater depths common salt would be met, and in 1852 
 the sinking of two shafts was begun. At the end of five 
 years common salt was found at a depth of 330 meters ; 
 but in reaching the deposit it was necessary to penetrate 
 250 to 280 meters of potassium and other salts. 
 
 Soon thereafter similar discoveries were made at Neu 
 Stassfurt, Loderburg near Stassfurt, and at Douglashall 
 near Westeregeln. In a word, boring followed boring, 
 not only north of the Harz Mountains, but to the south- 
 ward and elsewhere, and mine after mine was opened at 
 such frequent intervals as to increase the number, soon, to 
 more than 150, thereby taxing the ability of the newly or- 
 ganized German potash syndicate to control the situation. 
 
 387. Americans buy a German potash mine. — Finally 
 the Virginia-Carolina Chemical Company of the United 
 States purchased a German mine, and on July 1, 1910, when 
 the proposed renewal of the German potash syndicate 
 failed, large contracts for potash salts, continuing for sev- 
 eral years, were made by certain mine owners with Ameri- 
 can fertilizer manufacturers. 
 
 388. The famous potash contracts. — The reign of high 
 prices for potash salts and the end of the former great Ger- 
 man monopoly seemed now to have arrived. At this junc- 
 ture the Reichstag passed a measure, practically creating a 
 government monopoly of the potash salts. This situation 
 soon led to diplomatic exchanges on the subject between 
 the United States and Germany. As a result of this and 
 subsequent agitation a new syndicate was formed, and the 
 American contracts have finally been otherwise adjusted 
 or withdrawn. 
 
 389. Mode of occurrence and distribution of potash 
 deposits in Europe. — In the course of the search for these 
 saline deposits in Germany, it has been found that they are 
 
236 FERTILIZERS 
 
 not confined to any particular geological formation, for 
 they occur from the Permian to the Tertiary, though the 
 deposits near Stassfurt underlie the "Bunter" sandstone 
 of the Triassic period. 
 
 The following shows the arrangement of the deposits 
 in the order from top to bottom in which they are more 
 commonly found in the vicinity of Stassfurt : — 
 
 Alluvial deposits. 
 
 Diluvial deposits. 
 
 " Bunter " (Brown) sandstone (Triassic). 
 
 Gypsum, anhydrit, red clay, etc. 
 
 Newer common salt (a later secondary formation, 
 frequently lacking). 
 
 Anhydrit (anhydrous calcium sulfate). 
 
 Salzthon. 1 
 
 Carnallit region. 
 
 Kieserit region. " Abraum " salts. 2 
 
 Polyhalit region. 
 
 Older common salt. 
 
 Anhydrit. 
 
 Frequently kainit is found in the upper part of what is 
 essentially the carnallit region, but its presence is not 
 universal. 
 
 Schonit, sylvanit, and many other minerals also occur 
 in these deposits, though not usually in great quantities. 
 
 390. The chemical composition of the more important 
 potash salts is given in the following table : — 
 
 1 The Salzthon is made up of three layers, consisting at the bottom 
 of calcium sulfate, in the middle of magnesia (uncombined) and alumina, 
 and at the top of clay and from 40 to 50 per cent of magnesium carbonate. 
 This forms an impervious and protecting cover for the potassium and 
 magnesium salts below. 
 
 2 A term applied because these salts were over, and in the way of 
 getting at, the common salt, which necessitated their removal. 
 
POTASSIC FERTILIZERS 
 
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238 FERTILIZERS 
 
 391. Duration of the deposition of potassium salts. — 
 In the common salt are to be found thin bands of anhydrit 
 which have been taken to represent the records of yearly 
 deposits of gypsum during the colder season of the year. 
 Based upon this and other features connected with the 
 deposits, it was estimated, in 1864, that they might have 
 been formed in 1500 years ; but later estimates * place 
 the time at from 10,000 to 13,000 years. At all events 
 there seems to be no doubt that the deposition took place 
 in a salt inland lake either fed by springs or having for a 
 long time a continued or intermittent connection with the 
 ocean. 
 
 392. Natural deposits of potassium salts elsewhere. — 
 Up to the present time no discovery of large and important 
 deposits has been made aside from those in Germany and 
 a few in Austria. The occasional rumors of really im- 
 portant discoveries in the United States still lack confir- 
 mation. The discovery of such deposits at any time need 
 not, however, be a matter of surprise, for it would seem 
 that elsewhere than in Europe, lying above the salt de- 
 posits of like origin, the potassium and magnesium salts 
 of the mother liquors may likewise have crystallized out ; 
 and they may also have been similarly preserved from the 
 action of water by a natural protecting cover, just as they 
 are by the " Salzthon " in Germany. 
 
 393. Kainit. — The most important of the natural 
 salts, used directly as a fertilizer, is kainit (see analysis, 
 p. 237), which, though it contains potassium sulfate, also 
 carries large quantities of chlorids. It is used somewhat 
 extensively in Europe, due in part to the low transportation 
 charges. Kainit has been employed to some extent in the 
 
 1 Die Salzindustrie von Stassfurt und Umgegend von Dr. Precht, 
 Stassfurt, 1889, p. 5. 
 
POTASSIC FERTILIZERS 239 
 
 United States for direct application to the soil, though its 
 chief use has been in compounding " complete " commer- 
 cial fertilizers. 
 
 The employment of kainit in fertilizer mixtures is 
 usually indicated by the fact that their chlorin content, 
 in such cases, is usually a little more than twice as great as 
 the per cent of potash. 
 
 Because of its chlorin content, kainit is to be avoided 
 in the growing of sugar beets and tobacco, and also in 
 the production of potatoes, if they are intended for starch 
 manufacture. This is due to the depressing effect of chlorin 
 upon the starch and sugar content of certain plants, pro- 
 vided that the application is made in the spring in which 
 the crops are grown. In the case of tobacco the chlorin 
 affects injuriously the color of the ash, and also the burn- 
 ing quality. Extended experiments in Europe have dis- 
 closed the fact that good crops may be secured, and that 
 this ill effect may be avoided, by using extra heavy appli- 
 cations of kainit in the year preceding the one in which 
 these sensitive crops are to be grown, and by omitting it en- 
 tirely the following spring. It has been found, in such cases, 
 that no serious losses result from leaching, and the subse- 
 quent efficiency of the potash is not materially endangered. 
 
 394. Sylvanit and carnallit. — Another crude but less 
 abundant salt, often applied directly to the land, is syl- 
 vanit. This consists chiefly of chlorids and contains 
 about 12 per cent of potash. It is sold in Europe at a 
 lower price than kainit. 
 
 Carnallit. — In Germany even the crude carnallit, 
 containing about 9 per cent of potash, is also applied 
 directly as a fertilizer ; but it can neither be transported 
 long distances nor can it be stored with safety in moist 
 places because of its hygroscopic character. 
 
240 FERTILIZERS 
 
 395. Muriate of potash. — The manufactured potash 
 salt exported most extensively from Germany is the 
 muriate of potash. The grade chiefly employed in agri- 
 culture is the one containing from 48 to 50 per cent of 
 potash, equivalent to from 80 to 85 per cent of potassium 
 chlorid. The remaining 15 to 20 per cent consists chiefly 
 of common salt, associated with small amounts of sodium 
 and magnesium salts and a little water. 
 
 396. High-grade sulfate of potash. — The grade of 
 sulfate of potash most commonly manufactured and sold 
 for agricultural purposes in the United States is that con- 
 taining from 47 to 48.5 per cent of potash, or about 90 
 per cent of potassium sulfate. This is usually designated 
 as " high grade " sulfate of potash, in order to distinguish 
 it from a lower grade which contains large amounts of 
 magnesia, in addition to potash. The small amounts of 
 other ingredients in this potash salt are given in the pre- 
 ceding table (p. 237). 
 
 397. Double sulfate of potash and magnesia, or double 
 manure salt. — Following the foregoing manufactured 
 potash salts in agricultural importance, in the United 
 States, is the double sulfate of potash and magnesia, also 
 known as " double manure " salt, containing from 25 
 to 27 per cent of potash, or approximately 50 per cent of 
 potassium sulfate. The fact that this salt also contains 
 34 per cent of magnesium sulfate (MgS0 4 ), and that it 
 is essentially free from chlorids, makes it especially ap- 
 plicable for soils which may possibly lack magnesia, and 
 for situations where sulfur is possibly needed or where 
 chlorin should be avoided. 
 
 This salt should not be employed as a source of potash 
 on soils already relatively too rich in magnesia. 
 
 At the present time potash in the two sulfates costs, 
 
POTASSIC FERTILIZERS 241 
 
 in the United States, about one and one-quarter cents 
 per pound more than in muriate of potash. 
 
 The double sulfate of potash and magnesia has been 
 used by Goessmann and Brooks at the Massachusetts 
 experiment station with especially good results, in com- 
 bination with other fertilizing ingredients, in the manuring 
 of apple trees. 
 
 398. Double carbonate of potash and magnesia. — 
 The double carbonate of potash and magnesia is a hydrous 
 salt, also prepared in Germany, which has been used in 
 several instances with excellent results in the United States. 
 The material, according to an analysis made at the Massa- 
 chusetts experiment station, was found to contain 18.5 
 per cent of potash and 19.5 per cent of magnesia. 
 
 In experiments at the Rhode Island experiment station 
 it was found especially helpful in cases where not only 
 potash but also an alkaline treatment of the soil was 
 demanded; hence it is to be recommended wherever 
 magnesia is not already present in too great amounts and 
 where muriate of potash and sulfate of ammonia either 
 fail to produce their full effect or are toxic, because of an 
 acidic condition of the soil. 
 
 399. Silicate of potash. — A silicate of potash for 
 agricultural use, containing from about 24 to 27.6 per 
 cent of potash, has been prepared in Germany and dis- 
 tributed in this country for experimental purposes. It 
 was thoroughly tested by Brooks in Massachusetts and 
 found to be a valuable fertilizer, ranking in efficiency 
 between the muriate and the high-grade sulfate of potash. 
 It is, however, of less interest than otherwise, because its 
 manufacture is said to have been discontinued. 
 
 400. Potassium carbonate (Pearl ash). — Potassium 
 carbonate (Pearl ash) and so-called " potashes," consisting 
 
242 ' FERTILIZERS 
 
 of potassium carbonate and potassium hydrate, have been 
 used as fertilizers to a small extent, and also in compost 
 heaps. The former compound has found considerable 
 application in the growing of tobacco. In experiments 
 at the Rhode Island experiment station, covering a period 
 of seventeen years, it has been found to give, with most 
 crops, materially better results on a silt loam soil of acid 
 character than an equivalent amount of potash in muriate 
 of potash. Had the soil been alkaline at the outset, or 
 nearly so, doubtless the reverse might have been true, as 
 was found by W. P. Brooks in certain experiments in 
 Massachusetts. 
 
 401. Greensand. — A natural potash mineral of very 
 low grade, but yet of some fertilizing value, which has been 
 used more or less extensively as a manure, at points 
 near where it occurs, is " greensand " or " greensand 
 marl." 
 
 This has generally been supposed to be a sea-bottom 
 deposit, but it has recently been asserted that similar 
 zeolitic compounds are probably formed by the action of 
 magmatic waters. Greensand occurs widely, but the 
 deposits of chief interest in the United States are found in 
 New Jersey. According to Cook, the material has an 
 average content of about 5 per cent of potash, and it often 
 contains in addition from 1 to 2 per cent of phosphoric 
 acid. The greensand is a hydrated silicate of iron and 
 potassium, a species of glauconite. Its action is slow, 
 as might be expected, and the effects of a single heavy 
 application are visible for a dozen years. It, like the other 
 zeolites, is capable of being decomposed by hydrochloric 
 acid, and hence it readily parts with the lime, magnesia, 
 soda, and potash which it contains. 
 
 Much virtue is ascribed by many writers to these zeolitic 
 
POTASSIC FERTILIZERS 243 
 
 compounds by reason of the fact that the bases are mu- 
 tually interchangeable, and because of the prominent part 
 they are supposed to play in giving to the soil its ability 
 to absorb and hold lime, potash, and magnesia, when they 
 are applied for manurial or amendatory purposes. 
 
 It has been proposed by H. Wurtz x to utilize the green- 
 sand as a source of potash by fusing it with calcium chlorid, 
 a method employed recently by Cushman and others for 
 treating potash feldspars. 
 
 402. Phonolite, nepheline, alunite, leucite, and feld- 
 spars as sources of potash. — It was suggested long ago 
 by Storer 2 and others that certain feldspars (orthoclase 
 feldspar, K 2 • A1 2 3 • 6 Si0 2 , if pure, contains 17 per cent 
 of potash) might possibly be so finely pulverized as 
 to make them valuable fertilizers. Especial interest 
 was recently awakened in the subject by Cushman, 3 
 who claimed to have found feldspar, thus prepared, of 
 decided value in the growing of tobacco. 
 
 It has been shown by F. Schacke, Tacke, and Popp, 4 
 and by H. von Feilitzen, 5 that powdered phonolite and 
 nepheline ((Na • K) 2 0(A1 2 3 • 2 Si0 2 )) were of some value 
 as potash fertilizers, but were far inferior to the Ger- 
 man potash salts. The results with feldspar and with 
 alunite were, however, too poor to make them worthy 
 of consideration as practical potassic fertilizers. The 
 value of finely ground feldspar has also been carefully 
 studied by Hart well and Pember. 6 They employed a 
 finely ground product capable of passing a screen having 
 
 1 Storer, Agriculture, 2 (1897), 487. 
 
 2 Agriculture, 2, 1897. 
 
 3 Bui. 28, Office of Public Roads, U. S. Dept. of Agr. 
 4 Chem. Ztg., 35, 1222; Abs. Chem. Abstracts, 6, 1048. 
 6 Deut. Landw. Presse, 38 (1911), 737, 738. 
 
 6 Bui. 129, Agr. Exp. Sta., R. I. State College. 
 
244 
 
 FERTILIZERS 
 
 A.L , 1 i 
 
 l/\ k 
 
 
 
 -~M 
 
 
 n 
 
 
 
 
 ifialSj 
 
 
 
 *$ 
 
 _ J ~ 
 
 
 
 ^as. 1 
 
 Imi 
 
 « 
 
 
 
 
 
 No potassium 
 
 11 grams ground potash 
 feldspar (K 2 0, 9.09 %) 
 
 2 grams sulfate 
 of potash 
 
 Fig. 24. — Treatment of Millet. 
 
 Ground feldspar Sulfate of potash 
 
 Fig. 25. — Treatment of Wheat. 
 
POTASS IC FERTILIZERS 245 
 
 200 meshes to the linear inch, and containing about 9 per 
 cent of potash, 3 per cent of soda, and less than 0.4 
 per cent of lime. The work was done in pots which were 
 supplied regularly with water to the optimum limit, where- 
 by the conditions for bringing the potash into solution 
 were far better than those usually met with in farm 
 practice. 
 
 In the course of these experiments, beans, wheat, and 
 Japanese millet (Panicum crus-galli) were grown. As a 
 result it was found that the feldspar possessed such slight 
 value as a fertilizer that no one could think of using it to 
 replace the German potash salts. 
 
 It has been proposed that leucite (K 2 • A1 2 3 • 4 Si0 2 ), 
 containing 22 per cent of potash, might be heated with 
 salts of lime or soda whereby the solubility and efficiency 
 of the potash for plant production would be increased. 
 Although it is admitted that much is gained by such treat- 
 ment, yet the product has never been placed in successful 
 competition with the German potash salts. 
 
CHAPTER XVIII 
 
 THE THEORY AND PRACTICE OF POTASH FERTILIZATION 
 
 The fact that the ocean contains far more sodium salts 
 than potassium salts is explained on the ground that 
 sodium is far more easily removed than potassium, from 
 its zeolitic and other combinations, by the natural pro- 
 cesses of leaching. This is also well illustrated by the 
 well-known fact that in the natural weathering of certain 
 basic rocks the relative potassium content increases pro- 
 gressively, whereas the relative sodium percentages be- 
 come less. 
 
 403. The alleged ill effects of the chlorin of potassium 
 and other salts. — According to A. Mayer, 1 calcium and 
 magnesium chlorids are not particularly injurious to 
 meadow grasses. It is asserted by L. von Wagner that 
 chlorids are not good for beets and potatoes, but he doubt- 
 less refers to their depression of the sugar and starch con- 
 tent, which can be avoided by making the applications 
 the preceding year. 
 
 It has been explained by O. Loew 2 that the ill effect 
 of chlorids is probably due to the liberation of hydro- 
 chloric acid in the plant cells and to the fact that, unlike 
 nitric and sulfuric acids, little of it is assimilated, on 
 which account the accumulation soon reaches toxic limits. 
 
 In discussing the beneficial action of the carbonate, sul- 
 
 1 Lehrbuch der Agrikulturchemie (1886), 295. 
 
 2 Bui. 18, U. S. Dept. of Agr., Div. of Veg. Phys. and Path., p. 18. 
 
 246 
 
POTASH FERTILIZATION 247 
 
 fate, nitrate, silicate, and phosphate of calcium, Ullmann l 
 says that calcium chloric! is injurious to plant life. 
 
 It is stated by Griffiths, 2 based upon observations by 
 Jamieson and Munro, that potassium chlorid is a plant 
 poison and that investigations in England and on the con- 
 tinent of Europe have shown it to be an unreliable potash 
 manure. It must, however, be recognized that the danger 
 was greatly overdrawn by Griffiths in view of the fact 
 that enormous quantities of muriate of potash are used 
 throughout the world, with unquestionably good results. 
 
 Certain early experiments by Nobbe, 3 with buckwheat, 
 have been very generally cited in the past in support of 
 the alleged benefit derived by plants from chlorin, but 
 A. Mayer 4 holds that Nobbe attached undue weight to the 
 matter. Nevertheless, observations on potatoes by Pfeif- 
 fer 5 are said to indicate that chlorin was helpful, yet 
 Pagnoul found, on the contrary, that chlorin was injurious 
 to the growth of potatoes when grown on a sandy (sili- 
 cious) soil. It should be recalled in this connection that am- 
 monium chlorid has also been used by some experimenters 
 with good results, whereas others consider it a plant poison. 
 
 404. Reasons for the diversity of ideas concerning 
 chlorids. — In an attempt to throw light on the reason 
 for the quite contrary views of so many leading authorities, 
 Wheeler and Hartwell 6 experimented with several different 
 chlorids. Calcium chlorid was highly toxic to potatoes 
 on an acid soil, but either caustic magnesia or slaked lime 
 was shown to be capable of correcting the condition. 
 
 1 Kalk unci Mergel (1893), 9. 
 
 2 A Treatise on Manures, p. 225. 
 3 Landw. Vers.-Sta., 6, 118; also 13, 398. 
 4 Landw. Vers.-Sta., 49, (1901). 
 6 Landw. Vers.-Sta., 49, 349-385. 
 
 6 loth An. Rpt. R. I. Agr. Expt. Sta. (1902), 289-304. 
 
248 ' FERTILIZERS 
 
 Magnesium chlorid was not found to be toxic for barley 
 under the same conditions, yet ammonium chlorid was 
 exceedingly toxic. In the latter case the toxicity was 
 wholly corrected by calcium carbonate. The same re- 
 sult was also secured with caustic magnesia, after allow- 
 ing ample time for it to become well carbonated in the soil. 
 In other experiments in which ill effects were observed 
 from the use of muriate of potash, these were completely 
 overcome, and the fertilizer was made to produce normal 
 results by the employment with it of basic slag meal or 
 other basic substances. 
 
 In field experiments at the Rhode Island experiment 
 station, potatoes of excellent cooking quality have been 
 grown annually, with few exceptions, for a period of twenty 
 years with muriate of potash as the sole source of potash. 
 These results followed, even though the potash salt was 
 applied in the spring, immediately before planting. Slaked 
 lime had, however, also been applied periodically to the 
 soil, which may have been an important factor in bring- 
 ing about such a result. 
 
 From these various experiments it appears probable 
 that the highly toxic effects, reported as due to chlorids, 
 may often have been caused, in consequence of a lack of 
 basic substances in the soil. In fact, Schultz, of Lupitz, 
 demonstrated conclusively that occasional applications 
 of marl were necessary on the light acid soil of his sec- 
 tion of northern Germany, in order to insure good 
 results from repeated applications of the German potash 
 salts. 
 
 It has been pointed out by H. Ley * that neutral salts 
 prevent or check dissociation. It is possible, therefore, 
 that the lessening or hindering of unfavorable dissociations, 
 
 1 Ber. der deut. chem. Gesell., 80, 2192. 
 
POTASH FERTILIZATION 249 
 
 induced in the soil by the use of chlorids, may account in 
 some measure for the benefit derived from lime and other 
 basic substances. 
 
 405. The use of chlorids increases the need of liming. — 
 When chlorids of potassium and other bases are used on 
 soils well supplied with carbonate of lime, double decom- 
 positions result whereby the chlorin unites with the lime 
 and magnesia, forming the corresponding chlorids. These 
 chlorids, in reasonable quantities, are not only not ob- 
 servably toxic in the presence of an excess of carbonate of 
 lime ; but, owing to their high solubility, they readily 
 leach away in seasons of heavy and frequent rainfall. 
 This is true especially if the chlorid of potassium is 
 applied a few months, or preferably the autumn or spring, 
 preceding the growing of such crops as are most subject to 
 injury by chlorin. 
 
 Muriate of potash is reported by many as giving 
 usually slightly greater yields of potatoes than the sulfate 
 of potash, though the tubers are often claimed to be of 
 inferior cooking quality. In regions of heavy rainfall, 
 and where plenty of lime is used, the danger in this respect 
 seems to be greatly lessened or overcome. 
 
 406. The fate of sulfate of potash in the soil. — 
 Sulfates are less objectionable in the soil than the chlorids, 
 for the reason that plants require and utilize considerable 
 sulfur. Furthermore under temporary or long-continued 
 anaerobic conditions due to heavy rainfalls, sulfates are 
 readily reduced by bacterial action, with the result that 
 sulfide are formed from which even so weak an acid as 
 carbonic acid may disengage hydrogen disulfid, at the 
 same time forming carbonates. 
 
 When sulfate of potash is employed on soils rich in lime, 
 one result of the exchange of bases is the production of 
 
250 • FERTILIZERS 
 
 calcium sulfate. This salt is relatively insoluble, for 
 about 400 parts of water are required to effect the solution 
 of 1 part of it, whereas calcium chlorid soon liquefies upon 
 exposure to the air. 
 
 On this account, especially if the conditions are 
 occasionally favorable to reduction, the soil may not 
 become so rapidly depleted of its supply of lime when 
 using sulfate of potash as when muriate of potash is used. 
 
 407. Concerning the retention of potash by soils. — 
 It was already known in the time of Aristotle that common 
 salt is partly removed from solution upon leaching it 
 through sand or soil. It was also shown by Way, in 1850, 
 that when sulfate and muriate of potash are applied to 
 ordinary soils, the sulfuric acid and chlorin appear in the 
 drainage waters combined with lime and magnesia, and 
 that the potash is held quite completely and tenaciously 
 in the soil in zeolitic (zeolites are combinations of alumina, 
 silica, water, and the bases lime, magnesia, soda, or potash, 
 or various combinations of these bases) and other mineral 
 and organic chemical combinations. 
 
 It is now maintained by physicists and physical chem- 
 ists that the phenomenon of absorption may embrace three 
 distinct processes : (1) a mechanical inclusion called 
 imbibition, illustrated by the absorption of water by a 
 sponge or by soil ; (2) the partial taking up of the dissolved 
 substance to form a new compound or a solid solution l 
 such as is claimed to result in the absorption of phosphoric 
 acid, by lime, or by ferric oxid ; (3) absorption which is 
 
 1 A solid solution is a crystalline, amorphous, homogeneous solid 
 capable of changing its composition with the changing concentrations 
 of the liquid solution in contact with it. A definite compound, on the 
 other hand, is "stable in contact with a liquid solution of its constituents 
 over a measurable range of concentration." 
 
POTASH FERTILIZATION 251 
 
 the concentration or condensation of the substance in 
 solution on the surface of the absorbing medium. 
 
 It has been held by Cameron that potash is probably 
 held in soils by absorption. 
 
 Notwithstanding that in laboratory experiments, in 
 which relatively small amounts of soil are usually em- 
 ployed, the removal of potassium from weak solutions 
 of potassium sulfate and of muriate of potash is never 
 complete ; yet the conditions are entirely unlike those in 
 field operations, in which the amount of material is most 
 minute in its relation to the great volume of soil. It may, 
 nevertheless, be true that on sandy soils, which are greatly 
 deficient in clay, silt, and vegetable matter, potash salts may, 
 in extreme cases, be subject to moderate losses by leaching, 
 and they should consequently be used with some caution. 
 
 408. The teachings of the Rothamsted investigations. — 
 In the drainage waters from the unmanured experi- 
 mental plots of the Broadbalk wheat field at Rothamsted, 
 Voelcker found 1.7 parts of potash per million, whereas 
 in the drainage waters from the other plats receiving as 
 much as 300 pounds of sulfate of potash per annum, he 
 found only 2.9, 3.3, and 4.5 parts per million. An ex- 
 amination of the same soils by Dyer showed that about 
 half of the potash applied, in excess of that removed by 
 the crops, during a fifty-year period, was still present in 
 the upper nine inches of soil, and much of it was still soluble 
 in a 1 per cent solution of citric acid. Still further por- 
 tions of the excess of potash were found in the second and 
 third nine inches, which were also found to be soluble in 
 the citric acid solution. 
 
 409. Various factors affecting absorption. — Absorption 
 appears to be dependent upon at least the following 
 factors : — 
 
252 
 
 FERTILIZERS 
 
 (1) The solubility of the given substance in the solvent 
 employed, although the relation is as yet unknown. 
 
 (2) The character of the absorbing substance, though it 
 
 Full ration of 
 sodium carbonate 
 
 Full ration of potassium 
 carbonate 
 
 Fig. 26. — Treatment of Spinach. 
 Both lots limed and fertilized alike with nitrogen and phosphoric acid. 
 
 is uncertain in how far this is determined by the area of 
 exposed surface and by the character of the surface in- 
 volved. 
 
POTASH FERTILIZATION 253 
 
 (3) In a given solvent the rate of absorption of different 
 substances in solution is variable, even with one and the 
 same absorbing medium. This is so marked in some cases 
 that partial separations of two different salts in the same 
 solution may be thus made. 
 
 (4) Selective absorption from electrolytes, as when 
 potassium chlorid is filtered through soil, cotton, or other 
 absorbents. In this case the filtrate not only becomes 
 less concentrated, but even contains free hydrochloric acid. 
 
 (5) The rate of absorption increases with the concen- 
 tration of the solution and with the amount of the absorb- 
 ent or of its effective surface. 
 
 410. Potassium essential to plant growth. — It is fully 
 accepted that potassium is absolutely essential to plant 
 growth, even notwithstanding that it may, for many kinds 
 of plants, be partially replaced by sodium, in connection 
 with one or more of its possible functions. The degree, 
 however, of even this partial replacement appears to be 
 largely dependent upon the particular kind of plant 
 involved. 
 
 411. Potassium aids carbohydrate formation. — It 
 has been found that the curtailment of the potassium 
 supply exerts a serious effect upon the formation of car- 
 bohydrates, such as starch, sugar, and cellulose; and in 
 actual field practice certain crops especially rich in starch 
 and sugar seem to require its liberal employment. 
 
 412. Other functions of potassium. — It is now also 
 held that potassium performs valuable functions in the 
 formation of the proteins, and that it aids cell and nuclear 
 division. It has also been asserted by Loew that potas- 
 sium acts as a condensing agent, which would facilitate 
 the building up of carbohydrates from formaldehyde, as 
 Loew has previously suggested. 
 
254 FERTILIZERS 
 
 413. Potassium increases the size of the individual 
 grains of cereals. — In experiments by Hellriegel and 
 Wilfarth it was found that, with the supply of phosphoric 
 acid or of nitrogen curtailed, the quantity of grain was 
 greatly lessened; but yet the weights of the individual 
 kernels were but slightly, or not at all, affected. When, 
 however, the supply of potash was curtailed, the size of 
 the individual grains became smaller, and the formation 
 and translocation of starch was soon interfered with or 
 prevented. 
 
 In the later years of the barley experiments at the 
 Rothamsted experiment station, after a lack of potash 
 became evident, it was found that the average weight of 
 the grain per bushel for a period of fourteen years was 
 greater where potassium salts were used in the fertilizer, 
 and the average weight per kernel was increased thereby 
 in an even far greater degree. 
 
 414. Effect of potassium on photosynthesis. — Other 
 experiments at Rothamsted with mangel wurzels show 
 that with the leaf production varying but little, the addi- 
 tion of potassium salts to the other fertilizers increased 
 the yield of roots nearly two and one-half times. When 
 these roots were analyzed, it was found that the increase 
 in weight was due almost wholly to the increased produc- 
 tion of sugar and of other carbohydrates. It would 
 appear, therefore, that the process of photosynthesis in 
 the leaf and the consequent possibility of the storage in 
 the roots of the products elaborated by the leaves, is 
 largely regulated by the potash supply available to the 
 plant. In this instance the crop of roots was increased, as 
 a result of the use of the potassium salts, from 12 to 29 
 tons and the total product of sugar from 0.797 ton to 
 2.223 tons. 
 
POTASH FERTILIZATION 255 
 
 415. Potassium in connection with turgor. — Notwith- 
 standing that many writers even yet refer to " the func- 
 tion " of potassium salts as if potassium performed only 
 the function which has just been discussed, it appears 
 probable that there may be several. It has even been 
 asserted by Copeland l that potassium is both a direct 
 and indirect factor in maintaining the turgor of the plant. 
 The importance of this conclusion may, however, be 
 doubted in view of the work of De Vries, 2 who, though 
 upholding for a time the importance of certain organic 
 acids in maintaining turgor, concluded later that growth 
 may occur without turgor and that rapid growth may 
 lessen it. It is also asserted by Pfeffer that turgor can- 
 not furnish the energy essential to growth, but that on 
 the contrary it is a result of the conditions of growth. 
 
 416. The functions of potassium not necessarily shown 
 by the result which its absence produces. — As concerns 
 the association of potassium solely with the function of 
 aiding in the formation and translocation of starch, 
 Pfeffer 3 is of the opinion that phosphorus may be as 
 necessary in that respect as potassium, and he affirms 
 " that the function of an essential element is by no means 
 directly indicated by the result which its absence pro- 
 duces." 
 
 417. Potassium as a neutralizer and carrier within the 
 plant. — It has been pointed out by Shimper 4 that or- 
 ganic acids are the normal product within the plant of the 
 synthesis of the proteins. In experiments by Mercadente 5 
 
 1 Bot. Gazette, 24 (1897), 411. 
 
 2 Bot. Ztg. (1879), 848. 
 
 3 The Physiology of Plants, translated by Ewart (1900), I, 141. 
 
 4 Zur Frage der Assimilation der Mineralsalze durch die griine 
 Pflanze. 
 
 6 Abs. Jahresb. Agr. Chcniie (1885), 257. 
 
256 ' FERTILIZERS 
 
 in which he grew certain species of Oxalis and of Rumex 
 without potassium, it was found that only one-eighth of 
 the normal amount of acid was produced, and that the 
 oxalic and tartaric acids formed were in combination with 
 lime. In this case, only small amounts of starch and sugar 
 were present in the sap of the plants. It is known that 
 the neutral and more especially the acid salts of potassium 
 and oxalic acid which are normally formed in these plants, 
 are toxic to them if they accumulate in undue quantities. 
 Nevertheless, it has been suggested by Wheeler and Hart- 
 well that potassium perhaps performs a valuable office in 
 the plant by forming soluble combinations with some of 
 these acid synthetical by-products, in which state they 
 may be readily transported to other parts of the plant, 
 where by their combination with lime they are transformed 
 into comparatively insoluble and non-toxic compounds, 
 and are eliminated from the circulation. In this case 
 potassium would not only act as a neutralizer, but also as 
 a convenient and even necessary transporting medium. 
 
 418. Potassium may contribute to the " luxury con- 
 sumption " of plants. — It has been shown by careful 
 investigation in Germany that a certain minimum of 
 lime, magnesia, potash, and soda is essential to plant 
 growth, but that plants require, nevertheless, a certain 
 excess of bases above these total minima which may be 
 supplied indiscriminately by any one or more of them ; 
 for this reason, if there is a lack of the other bases, potas- 
 sium may be helpful by virtue merely of supplying this 
 so-called (though necessary) " luxury " consumption. 
 
 419. Certain functions and effects of potassium salts 
 in soils. — In some cases potassium salts may perform a 
 useful function in the soil by virtue of increasing the sur- 
 face tension of the soil solution, by which the rate of the 
 
POTASH FERTILIZATION 257 
 
 capillary movement of water toward the surface and to- 
 ward the plant roots is increased. 1 It is also asserted by 
 King (I.e.) that the presence of salts in the soil lessens 
 evaporation from the surface, so long as they remain in 
 solution, and if they crystallize out they serve in a measure 
 as a mulch. 
 
 Attention has recently been called by Muntz and 
 Gaudechon 2 to benefit which they allege may result in 
 certain cases from the addition to soil of soluble fertilizer 
 salts, since they lower the vapor pressure of the water 
 and induce a distillation, to the affected points, of water 
 vapor from the soil below and from the air above. 
 
 If soils are too open, the use of the German potash salts 
 may gradually improve their physical condition, by vir- 
 tue of the fact that they react with calcium carbonate, if 
 present, to form potassium carbonate, which salt has a 
 highly deflocculating action. If, on the contrary, a soil is 
 exceedingly fine, like many clay soils, the potassium car- 
 bonate may by the same action injure the existing con- 
 ditions, rendering the soils too compact and consequently 
 difficult to till. It may make them at the same time also 
 less suited in other respects to support plant growth to 
 the best advantage. In these particulars the varying 
 effects are analogous to those resulting from the residual 
 soda of nitrate of soda (Section 254). 
 
 420. The effect of potassium salts on legumes. — The 
 beneficial effect of potassium salts upon clover and other 
 legumes has long been generally recognized, and many 
 soils which have been found to be deficient in potash have 
 come to be termed " clover sick." It is nevertheless 
 true that clover sickness may sometimes be due to a lack 
 
 1 King, Text-book of the Physics of Agriculture (1901), p. 106. 
 2 Compt. rend., 48 (1909), 253-258. 
 S 
 
258 ' FERTILIZERS 
 
 of lime, to disease, or other conditions ; and one is not 
 necessarily justified in assuming which of the various 
 causes of the failure of clover may need to be dealt with, 
 without special knowledge of the particular locality and 
 of the soil concerned. 
 
 In view of the known promotion of the fixation of at- 
 mospheric nitrogen by certain plants, including the leg- 
 umes, when the associated bacteria are well supplied with 
 carbohydrates, it appears that at least one way in which 
 potassium salts may be helpful to the legumes is by in- 
 creasing the carbohydrate supply within the plant, by 
 which the organisms of the root nodules are made to work 
 more effectively. 
 
 In the permanent grass experiment at the Rothamsted 
 experiment station, the herbage in 1902, where a mineral 
 fertilizer containing phosphates, sulfate of potash, mag- 
 nesium salts, and sodium salts had been used in the past, 
 was 55.3 per cent legumes ; whereas where potassium salts 
 were omitted from the fertilizer mixture, the legumes 
 amounted to but 22.1 per cent; and where nitrogen was 
 applied and the potassium salts were omitted, no legumes 
 were to be found. 
 
 421. The effect of a lack of potassium on grasses and 
 other plants. — On the plots of land at Rothamsted where 
 potash was most deficient, the grasses very largely failed 
 to produce seed and the stalks were weak and brittle. 
 This was assumed to be due to an insufficient devel- 
 opment of carbohydrates within the plants. It is further 
 mentioned by Hall that the grass possessed an abnormal 
 color, lacked chlorophyl, and exhibited other signs of 
 malnutrition. The leaves of Swedish turnips developed 
 under similar conditions a " flecked " appearance, mangel 
 wurzels were attacked by a leaf-spot fungus (Uromyces 
 
POTASH FERTILIZATION 259 
 
 beta), wheat developed much rust, even when little was 
 present elsewhere, and grass was attacked by various 
 fungi. 
 
 Whether the ill effects arising from a deficiency of potash 
 were due to a lack of general vigor or to an altered com- 
 position of the plant cells, Hall does not attempt to con- 
 clude, although he inclines to the former view. Concern- 
 ing these results, Hall cautions against giving too much 
 weight to such effects, in general farm practice, since the 
 manurial conditions were most unusual and had been 
 developed during the long term of years in which the ex- 
 periments had been in progress. i 
 
 422. Potassium salts act best in wet seasons. — The 
 effect of potassium salts upon wheat and barley, at Roth- 
 amsted, has been found to be far more favorable in wet 
 than in dry seasons, due possibly to its preventing pre- 
 mature ripening. The yield of barley in a dry season was 
 18.1 bushels per acre without the use of potassium salts, 
 whereas it was 30.8 bushels when they were employed. In 
 a wet season the yield in the first instance was 34.9 bushels, 
 and in the latter instance 41.4 bushels, per acre. It has 
 been found, in the case of root crops, that potash hastens 
 maturity; however, in barley and wheat the migration 
 processes are quite different from those involved in the 
 storage which takes place in root crops. 
 
 423. A lack of potassium more serious for some crops 
 than for others. — In the course of experiments which 
 have been in progress at the experiment station of the 
 Rhode Island State College since 1894, it has been found, 
 where potassium salts were omitted from the otherwise 
 complete fertilizer and sodium salts substituted for 
 them, that clover and timothy (Phleum pratense L.) 
 largely, and in some cases completely, disappeared. Nev- 
 
260 FERTILIZERS 
 
 ertheless, moderate crops of redtop (Agrostis vulgaris 
 With.) were still produced, although the plants gave evi- 
 dence of probable faulty seed development. Where the 
 potassium salts were omitted, dark spots appeared on 
 the leaves of potatoes, and even a blackening of the entire 
 leaf surface often resulted. This did not appear like, nor 
 was it recognizable microscopically as being identical 
 with, either the early or late blight of potatoes. The 
 plants, as would be inferred, died prematurely. 
 
 Notwithstanding that the conditions in this experiment 
 and in those at Rothamsted were quite unusual, it may 
 nevertheless be true that under conditions which exist 
 in farm practice instances sometimes occur where plant 
 diseases may become unusually severe, due to a lack of 
 potash or of a sufficient supply of other plant food in- 
 gredients, to insure normal plant development. 
 
 424. Potash conservation in the soil by sodium salts. — 
 It has been shown by Wilfarth and his co-workers at 
 Bernburg, Germany ; also at Rothamsted ; and by Wheeler 
 and Hart well in Rhode Island, that certain plants, when 
 supplied liberally with sodium salts, take up materially 
 greater quantities of it, and less of potash, than when no 
 sodium salts are applied. In fact, in the case of the Rhode 
 Island experiments, the conclusion seemed obvious that 
 plants supplied with the necessary minimum of potash 
 could, perhaps with equal advantage, use some soda to 
 replace a part or all of the excess of potash which they 
 might have removed from the soil, had it been present. It 
 appears, therefore, that nitrate of soda and the sodium com- 
 pounds associated with the German potash salts may con- 
 serve, somewhat, the potash stores of the soil by prevent- 
 ing a " luxury," or unnecessary, consumption of potash 
 by the plant. 
 
CHAPTER XIX 
 
 LIME AND ITS RELATION TO SOILS AND FERTILIZERS 
 
 Lime has been shown not only to be a corrective, in 
 the presence of an excess of magnesia or of certain other 
 substances, but also to be absolutely essential to plant 
 growth, and incapable of complete replacement by other 
 plant food ingredients. 
 
 425. The occurrence of lime. — Lime is present in 
 combination with carbonic dioxid and also with alumina 
 and silica in many of the representative rocks of the earth's 
 crust. It may be present in soils in the form of minute 
 crystals of apatite, or in other combinations of lime with 
 phosphoric acid; likewise in gypsum (calcium sulfate), 
 calcium carbonate, in zeolitic compounds, and as a con- 
 stituent part of decaying vegetable matter. 
 
 426. Distribution and effect of limestone. — Carbonate 
 of lime is widely distributed in the form of rock, and 
 in many respects it is the most important form of lime 
 found in soils. 
 
 Notwithstanding the wide distribution of limestone 
 rocks over most of the globe, there are nevertheless soils 
 upon which it appears probable that lime is sometimes 
 even needed as plant food, though perhaps in such cases 
 only in connection with restricted classes of plants. Gen- 
 erally, however, if 1 me is required at all, it is as a soil 
 amendment, either in a neutralizing or flocculating capac- 
 ity. As a neutralizer it exerts a powerful influence upon 
 
 261 
 
262 FERTILIZERS 
 
 the character of the microscopic soil flora, thus vitally- 
 affecting ammonification, nitrification, denitrification, and 
 nitrogen assimilation. 
 
 Lime also affects the development of certain diseases, 
 not only on the roots, but also on the aerial portions of 
 plants. 
 
 It is because of these many functions of lime in the soil 
 and of the many cases of contradictory effects, dependent 
 upon the character of the soil, upon the kind of plant 
 grown, and upon the particular plant disease involved, 
 
 Fig. 27. 
 Clover, where before liming it could not be grown successfully. It was 
 said to winter-kill, which was really seldom the case. 
 
 that the problems connected with the use of lime are of 
 a very complex character. 
 
 427. Kinds of lime used in agriculture. — " Burned " 
 lime, " rock " lime, " stone " lime, and " builder's "4ime 
 are various names given to the final product after the car- 
 bon dioxid of limestone or marble has been expelled by 
 heat. In this process 100 pounds of pure limestone (cal- 
 cium carbonate) lose about 44 pounds of carbon dioxid 
 and yield about 56 pounds of calcium oxid (CaO, or lime). 
 Most limestone is so impure that the product, after burn- 
 ing, usually contains not more than from 95 to 98 per cent 
 
LIME AND ITS RELATION TO SOILS 
 
 263 
 
 of lime ; and certain highly magnesian limestones yield, 
 upon burning, a product containing about 60 per cent of 
 lime and about 40 per cent of magnesia. 
 
 Dolomite is the most highly magnesian of limestones, 
 and it contains before burning 30.4 per cent of lime and 
 21.7 per cent of magnesia. 
 
 Magnesian limestones are common, yielding a burned 
 
 Unlimed Limed 
 
 Sulfate of ammonia 
 
 Unlimed Limed 
 
 Nitrate of soda 
 
 Fig. 28. — Treatment of Silene orientalis. 
 
 All fertilized alike with potash and phosphoric acid. A like amount of 
 
 nitrogen was used in each case. 
 
 product containing amounts of magnesia ranging from the 
 merest traces to about 40 per cent. 
 
 Burned limestone is often ground, without slaking, and 
 sold, without further treatment, for direct application to 
 the land. In other cases the lime is slacked by the addi- 
 tion of about one-third its weight of water, when there 
 results a fine, dry product known as " water-slaked," or 
 more commonly as " hydrated " lime (Ca(OH) 2 ). This is 
 proportionately poorer in lime than before slaking, on 
 
264 
 
 FERTILIZERS 
 
 account of the addition of the hydroxyl groups (OH). 
 Frequently lime is slaked by mere exposure to the 
 air, whereby it takes on water and carbon dioxid, form- 
 ing a mixture of calcium carbonate and calcium hydrate. 
 Upon long and complete exposure to the air, under the 
 most favorable conditions, hydrated lime and air-slaked 
 lime become practically reconverted into calcium car- 
 bonate. 
 
 Other sources of carbonate of lime for agriculture pur- 
 
 Unlimed Limed 
 
 Sulfate of ammonia 
 
 Unlimed Limed 
 
 Nitrate of soda 
 
 Fig. 29. — Carnations. 
 All fertilized alike with potash and phosphoric acid. A like amount of 
 nitrogen was used in each case. 
 
 poses are wood-ashes, the waste from the manufacture of 
 acetone, soda, and from other industrial processes. 
 
 The chief materials used for furnishing carbonate of 
 lime are, however, ground shell marl, ground oyster 
 shells, and ground limestone or marble. These are named 
 in their order of availability. Ground limestone and 
 marble are the least efficient, chiefly on account of their 
 crystalline structure. 
 
 428. The effect of lime on nitrogen availability. — It 
 
LIME AND ITS RELATION TO SOILS 265 
 
 often happens in soils which are deficient in carbonate of 
 lime that the application of burned, air-slaked, or hydrated 
 lime, ground limestone, or marl has an almost immediate 
 beneficial influence upon ammonification and nitrification. 
 Cases are on record where the efficiency of certain forms 
 of organic nitrogen, in soils, has been increased from two 
 to a dozen times, solely as the result of a single heavy 
 application of lime. 
 
 429. The effect of lime on denitrification. — The effect of 
 lime on compact clay or silt soils is to cause several small 
 particles to draw together by the process known as " floccu- 
 lation." As a result, the air more readily enters the soil, 
 whereby the conditions are usually rendered less favorable 
 for the destruction of nitrates, since denitrification is 
 essentially a reducing or anaerobic process. In fact, 
 Koch and Pettit 1 have shown that in soils with 25 per 
 cent or less of water the denitrifying organisms lie quies- 
 cent, but when the moisture content is increased, destruc- 
 tion of nitrates begins suddenly ; and considerable nitro- 
 gen is then liberated in the gaseous state It appears 
 probable that the critical percentage of moisture would 
 be found to vary somewhat with the physical character 
 of the soil. 
 
 430. The effect of lime on soil texture. — As suggested in 
 the preceding paragraph, liming greatly improves compact 
 silt and clay soils, especially if they are in such condition 
 that they tend to bake badly. This improvement is not 
 only due to hindering denitrification, but also in conse- 
 quence of the general effect of a more free circulation of 
 air, the creation of conditions more favorable to nitrifica- 
 tion, and finally, also, by virtue of increasing the penetra- 
 
 iCentralb. f. Bakt., II Abt., 26 (1910), 335-345, Abs. E. S. R., 23 
 (1911), 123. 
 
266 FERTILIZERS 
 
 bilityof the soil by water, whereby surf ace erosion is greatly 
 lessened. The storage of water in the soil is also increased, 
 and its subsequent capillary movement is better regulated 
 and adapted to properly supplying the needs of the plants. 
 Such soils, after being suitably limed, are fit to work much 
 earlier in the spring than those from which lime has been 
 omitted. 
 
 It is also true of light sandy and gravelly soils that the 
 use of lime often improves their condition by the mere 
 adding of fine material, which increases their lifting ca- 
 pacity for water. Furthermore, it is claimed that by the 
 chemical combination of the lime with silica and alumina 
 to form zeolitic compounds, the condition of the soil is 
 not only rendered better from a physical standpoint, but 
 also as concerns its ability to hold potash and other plant 
 food elements. 
 
 The physical character of light soils is also said to be 
 affected favorably by the adherence of lime to the surface 
 of the existing soil particles. 
 
 In all cases heavy liming is to be avoided on light soils, 
 especially in hot climates, and particularly if they are 
 greatly deficient in vegetable matter. In no case should 
 opportunity be lost to increase the supply of the latter, 
 even though lime is used with great care and in small 
 quantities. 
 
 431. The use of lime in connection with phosphates. — 
 The presence of calcium carbonate in soils may be expected 
 to insure that when superphosphates of any kind are 
 applied to them, some of the monocalcium phosphate will 
 revert with lime rather than entirely or chiefly with oxids 
 of iron and aluminum, as might otherwise be the case. 
 This is quite commonly of distinct advantage in view of 
 the fact that the phosphates of iron and aluminum, when 
 
LIME AND ITS RELATION TO SOILS 267 
 
 once formed, are considered as being less available sources 
 of phosphoric acid for plants, at least on acid soils, than 
 tricalcium phosphate. They are also less soluble than the 
 latter in weak acids, including even carbonic acid. 
 
 Large applications of burned or slaked lime, or even of 
 carbonate of lime, are said to be frequently important 
 factors in liberating phosphoric acid already locked up in 
 the soil in combination with iron and aluminum oxids, 
 as has been pointed out by Deherain. 1 
 
 The beneficial effect of applications of slaked lime upon 
 the subsequent efficiency of roasted iron and aluminum 
 phosphate, even for several years after the last applica- 
 tion of each, has been most strikingly demonstrated at 
 the agricultural experiment station of the Rhode Island 
 State College. 2 This benefit is usually assumed to be due 
 to the long-continued reactions resulting from the gradual 
 transformation of the calcium carbonate into the more 
 active bicarbonate, which then reacts more effectively 
 than the carbonate upon the iron and aluminum phos- 
 phates. It is possible likewise that other more complex 
 factors are also involved. 
 
 432. Lime as a destroyer of worms and slugs. — Much 
 has been written of the effect of lime in destroying worms 
 and slugs, and Storer 3 states that if but 3 to 4 tons of lime 
 are applied per acre, some insects may escape destruction, 
 but that it may be expected to be very effectual if from 
 7 to 8 tons of lime are applied per acre. It must be rec- 
 ognized, however, that on sandy or other light soils one 
 should seldom, if ever, use more than from 1000 to 2500 
 pounds of burned or slaked lime per acre, in a single ap- 
 
 1 Traite de Chemie Agricole (1892), 525. 
 2 Buls. Nos. 114 and 118. 
 3 Agriculture, 2 (1897), 545. 
 
268 FERTILIZERS 
 
 plication. It is but rarely that more than from 1 to 2.5 
 tons per acre would be required, on heavier soils, in order 
 to accomplish such changes as are immediately desirable. 
 For this reason it is believed that the practical significance 
 of liming, as a remedy for slugs and worms under 
 usual economic agricultural conditions, has been unduly 
 emphasized. 
 
 It has been suggested by English writers that freshly 
 slaked lime or, preferably, burned lime should be scattered 
 in clover fields or in stubble where insect pests are common. 
 This should be done, however, at or after dusk, or before 
 sunrise, since the effectiveness of the lime depends upon 
 its coming into direct contact with the worms or slugs, 
 which appear to be unable to withstand its caustic action. 
 
 433. Need of liming suggested by soil acidity. — Soils 
 are commonly referred to as acid which quickly and 
 intensely redden a blue litmus paper when brought in 
 contact with it under suitable conditions of moisture. 
 Unless such soils are very light and sandy, or are typical 
 subsoils, they usually yield immediately, without previous 
 extraction with hydrochloric acid, dark chocolate, brown, 
 or black extracts, upon stirring them with water and 
 dilute ammonium hydroxid. 
 
 It has been pointed out by Cameron and others of the 
 Bureau of Soils of the United States Department of Agri- 
 culture, that finely divided or porous substances which can 
 in no way be considered as acid, as, for example, cotton, 
 have, nevertheless, the property of absorbing the base 
 away from • blue litmus paper, whereupon it gradually 
 takes on the color of the acid or red litmus. It should be 
 remarked, however, that this reaction between litmus 
 paper and cotton takes place very slowly. On account of 
 these and similar observations and because some soils 
 
LIME AND ITS RELATION TO SOILS 
 
 269 
 
 which impart a red 
 color to litmus pa- 
 per have not shown 
 subsequent benefit 
 from liming (conclu- 
 sions drawn some- 
 times without suffi- 
 cient attention to 
 the requirement of 
 the particular 
 plant), the relia- 
 bility and value of 
 the litmus paper 
 test for ascertain- 
 ing if soils are in 
 need of liming, has 
 been seriously ques- 
 tioned from several 
 sides. It has been 
 shown, x however, 
 that, notwithstand- 
 ing this physical 
 absorptive property 
 of soils, such redden- 
 ing of blue litmus 
 paper does not re- 
 sult in the presence 
 of moisture and of 
 calcium bicarbon- 
 ate. Again, if a con- 
 siderable amount of 
 
 1 Bui. 139, Agr. Expt. 
 Sta., R.I. State College. 
 
270 FERTILIZERS 
 
 active calcium carbonate is present in a soil, the rain 
 water, and the soil solution charged with more or . less 
 carbonic acid derived from the air, and from decomposing 
 plant residues in the soil, must inevitably react with it to 
 form calcium bicarbonate, the quantity of which would 
 increase within certain limits with the quantity of carbonic 
 acid present. For this reason the rapid and intense red- 
 dening of blue litmus paper by a moistened soil, whatever 
 the reaction may be ascribed to, is an indication of a suffi- 
 cient lack of basic substances to possibly interfere with 
 suitable bacterial development and with the growth of 
 certain higher varieties of plants, unless lime or other 
 basic substances are employed. 
 
 434. Liming the most economic basic treatment. — 
 Whether, therefore, a soil is strictly acid or is sufficiently 
 lacking in bases to require their addition, even if for other 
 reasons than for the neutralizing of acidity, liming is 
 suggested as a suitable remedy. In fact, no other basic 
 treatment, excepting possibly in some cases with magnesia, 
 is either so economical, so lasting, or is it followed by such 
 general good results, as liming. 
 
 435. Chemical methods for determining the lime re- 
 quirements of soils. — Many methods have been pro- 
 posed from time to time for determining the lime require- 
 ments of soils, as, for example, (1) the adding of lime-water 
 to the soil, evaporating, and determining the lime remain- 
 ing uncombined, and (2) the bringing of soil in contact with 
 calcium carbonate and the measurement of the carbon 
 dioxid evolved either at the usual or higher temperatures. 
 In the latter case the period of treatment must be very 
 brief, on account of the progressive destruction of organic 
 matter and the consequent liberation of carbon dioxid 
 from it, which is in no way related to the reaction sought. 
 
LIME AND ITS RELATION TO SOILS 271 
 
 Soils are sometimes extracted with water, and the 
 watery extract is titrated by use of a suitable indicator, 
 taking cognizance of the probable presence of free carbonic 
 acid in the extract. 
 
 The foregoing are but a few of the methods proposed 
 for the quantitative measurement of the lime require- 
 ment of soils, but all fall short of perfection for practical 
 purposes for the reason that they may give the total of 
 basic absorption and chemical combination, or they may 
 give only a fraction of this requirement. The true end 
 point of the reaction in some cases is difficult to determine, 
 and, furthermore, the amount of lime actually demanded 
 to give the best results can only be approximated for 
 certain selected groups of plants, and even the individual 
 members of a group may vary among themselves in this 
 respect. It is also true that amounts of lime far less than 
 are shown by some of these quantitative tests are actually 
 preferable, for certain crops, to the full amounts in- 
 dicated. 
 
 It is nevertheless true that certain of these methods, 
 in the hands of one having a practical knowledge of the 
 differences in plant requirements, when applied to un- 
 known soils in conjunction with tests of soils the require- 
 ments of which have been previously determined, may have 
 very great value. On the other hand, however, they may 
 lead to very erroneous and faulty conclusions as to the 
 treatment, if placed in the hands of one having solely a 
 knowledge of the chemical and laboratory side of the 
 problem. 
 
 436. The effect of lime on vegetable decay. — It is 
 mentioned by Storer that lime performs valuable func- 
 tions in the soil by coagulating organic matter. 
 
 If burned or slaked lime is mixed with relatively fresh 
 
272 FERTILIZERS 
 
 vegetable matter, the first effect is to retard decomposition, 
 but if decay has already progressed to a considerable ex- 
 tent, its introduction, in reasonable amounts, is likely to 
 hasten decomposition almost from the outset. In fact, 
 the action of lime in compost heaps is generally so well 
 understood as to require no more than passing mention. 
 Lime is also highly important in hastening ammoni- 
 fication and the subsequent formation of nitrates from 
 vegetable matter ; because, in order that nitrification may 
 be active and progressive, there must be present some base 
 
 Unlimed Limed Unlimed Limed 
 
 Sulfate of ammonia Nitrate of soda 
 
 Fig. 31. — Cranberries under Varied Treatment. 
 
 All fertilized alike with potash and phosphoric acid. A like amount 
 
 of nitrogen was used in each case. The cranberry is shown to thrive 
 
 best on soil so acid as to be destructive to mangels. 
 
 such as lime, magnesia, potash, or soda to combine with 
 the nitric acid as it is formed, for otherwise the accumula- 
 tion of acid soon inhibits the activity of the nitrifying 
 organisms. 
 
 437. ' The effect of lime on nitrogen content of humus. 
 — ; It must be remembered that in the early stages of the 
 destruction of vegetable matter, the losses of carbon and 
 hydrogen are relatively great, due to their ready transfor- 
 mation under usual soil conditions into water and carbonic 
 acid. Thus the organic residue becomes for a time, on 
 
LIME AND ITS RELATION TO SOILS 273 
 
 the percentage basis, continually richer in nitrogen. In 
 this connection it should be stated that it has been shown, 
 on a soil greatly in need of liming which was kept for many 
 years chiefly in hoed crops, that liming lessened to a con- 
 siderable extent the total humus removable by extraction 
 with ammonium hydroxid ("matiere noire " of Grandeau), 
 but that the percentage of nitrogen in the humus was dis- 
 tinctly greater than before, thus showing the same general 
 action of lime on material already well humified, in an 
 acid soil, as on vegetable matter in a less advanced stage 
 of humification. This tendency of the nitrogen percent- 
 age to rise, after liming, is of interest in connection with 
 observations by Hilgard and others to the effect that the 
 higher the percentage of nitrogen in the humus, the greater 
 becomes the availability of its nitrogen to plants. This 
 helps also to explain the high fertility of soils well supplied 
 with calcium carbonate which have become heavily 
 charged with decaying plant residues. 
 
 438. Rational rotation and the turning under of sward 
 should accompany liming. — The ideal condition is reached 
 when a grass, clover, alfalfa, or other sod, plenty of 
 barn-yard manure, straw, or green crops are introduced 
 into the soil with sufficient frequency to maintain a suit- 
 able supply of vegetable matter with which to insure 
 proper tilth. This material also furnishes food to the 
 organisms which assimilate atmospheric nitrogen and at 
 the same time, through the action of lime, yields carbonic 
 acid to act upon the mineral constituents of the soil 
 These residues also furnish to the plant considerable sup- 
 plies of available nitrogen as ammonia and soluble organic 
 matter, but primarily as nitrates. 
 
 439. Avoidance of liming to conserve humus not wise. 
 — The idea that organic matter should be kept from de- 
 
274 FERTILIZERS 
 
 struction in the soil as long as possible, and that liming 
 should be avoided because it hastens such destruction, is 
 wholly exploded by the recent investigations of the mi- 
 croscopic soil organisms and of their several beneficent 
 functions ; nevertheless, liming should not be overdone. 
 
 Sufficient lime in its burned, hydrated, or air-slaked 
 condition, or as calcium carbonate, should be applied, to 
 
 Unlimed Limed Unlimed Limed 
 
 Sulfate of ammonia Nitrate of soda 
 
 Fig. 32. — Asparagus differently Treated. 
 
 All fertilized alike with potash and phosphoric acid. A like amount 
 
 of nitrogen was used in each case. It should be noted that a fourth 
 
 bundle is lacking at the left. This was because every plant died on 
 
 the plot which received sulfate of ammonia but no lime. 
 
 bring about a reasonably rapid humificationof the vegetable 
 matter, but at the same time care must be taken that 
 this latter supply is reasonably maintained. In this con- 
 nection it should be stated that it is universally understood 
 that the repeated employment of slaked or burned lime 
 in unduly large quantities without stable manure, green 
 manures, the turning under of sward, and without proper 
 fertilization must be avoided, or dire consequences are 
 
LIME AND ITS RELATION TO SOILS 275 
 
 likely to follow. This is not only true as concerns the 
 exhaustion of available potash and phosphoric acid, but 
 also because of the serious destruction of the vegetable 
 matter already in its various stages of decomposition. 
 Nevertheless, the frequent sweeping condemnation of the 
 use of slaked or burned lime without regard to the cost 
 of transportation and other conditions affecting its use 
 is equally to be avoided. On account of their ready 
 availability, such forms of lime should usually be applied 
 at intervals of from four to seven years, and, if employed 
 on suitable soils, in reasonable quantities, and at the right 
 point in such rotations as involve the periodic turning 
 under of a good grass sod, no fear of material injury to 
 the land need be entertained. 
 
 440. Carbonate of lime versus slaked or burned lime. — 
 At the present time in the United States certain experi- 
 ments conducted at the agricultural experiment station 
 of the Pennsylvania State College are being extensively 
 cited in the agricultural press, and elsewhere, as a basis 
 for the unqualified denunciation of the use of burned and 
 slaked lime. 
 
 Conditions of the Pennsylvania experiment. — In the 
 foregoing experiment, however, neither fertilizer nor 
 stable manure was used. Slaked lime was applied at 
 the rate of two tons per acre every four years, immediately 
 before Indian corn in a rotation of Indian corn, oats, wheat, 
 and clover. In comparison with it, like amounts of cal- 
 cium oxid were used in ground limestone. In the former 
 case the liming should preferably have preceded the 
 seeding to wheat and clover, and the order of the rotation 
 should have been reversed to give an opportunity for a 
 favorable trial of the slaked lime. In the case of the lime- 
 stone the application was divided into two equal parts, each 
 
276 FERTILIZERS 
 
 being applied in alternate years, thus giving it a distinct 
 advantage. As a result of the excessive quantity used, 
 and of the application of the slaked lime at the wrong 
 point in the rotation, it actually depressed many of the 
 yields of Indian corn. 
 
 The quantity of lime applied in the Pennsylvania ex- 
 periment in twenty years on the basis of the four applica- 
 tions, assuming a content of 70 per cent of calcium oxid, 
 was 11.200 pounds of actual calcium oxid per acre. The 
 soil was furthermore not greatly in need of liming, as has 
 
 No lime Ground limestone Hydrated lime 
 
 Fig. 33. — Alfalfa with Treatment under Farm Conditions. 
 All fertilized alike with potash and phosphoric acid. Quantities of 
 lime having the same total neutralizing value were used in each case. 
 
 since been shown by Brown, and as indicated also by 
 the fact that no great injury arose from several repeated 
 applications of ammonium sulfate on other plots. It 
 appears, therefore, that slaked lime was not only applied 
 at an unfavorable time, but also in excessive quantities. 
 
 Slaked lime highly beneficial in the Rhode Island ex- 
 periments. — In striking contrast to the foregoing results, 
 slaked lime has been used most successfully during a 
 period of twenty years in several crop rotations at the 
 agricultural experiment station of the Rhode Island 
 State College, on land so greatly in need of lime at the out- 
 
LIME AND ITS RELATION TO SOILS 277 
 
 set that beets, spinach, and lettuce could not be grown 
 successfully without it or other alkaline fertilizers or ma- 
 nures. This soil was, furthermore, so greatly in need of lime 
 that a single small application of sulfate of ammonia 
 became immediately toxic. It is interesting to note, 
 however, that even under these extreme conditions the 
 total quantity of calcium oxid employed (including any 
 magnesium oxid present) was equivalent to less than 
 3200 pounds of calcium oxid, per acre, in an interval of 
 nineteen years. Even though in most of the instances in 
 the Rhode Island -experiments, fertilizers were applied 
 exclusively, the crop yields, as a rule, have been well main- 
 tained, and in general less fertilizer has been used in the 
 later than in the earlier years. 
 
 The preceding experience shows, therefore, that too 
 much alarm should not be occasioned by the results of 
 experiments which have been conducted under unnatural 
 conditions, and with unreasonably large quantities of 
 slaked or burned lime. 
 
 Slaked lime becomes quickly carbonated. — It must further 
 be borne in mind that recent investigations have shown 
 that slaked and burned lime, if applied in reasonable 
 amounts, change quickly in the soil into the form of cal- 
 cium carbonate ; hence it is essentially, as concerns subse- 
 quent effect, as if it had been applied as such at the outset. 
 In the course of earlier experiments made by Heiden, he 
 concluded that in some cases lime remained in a caustic 
 state in the soil for years; it appears, however, that he 
 assumed that all lime found soluble in water and capable 
 of producing an alkaline reaction was necessarily present in 
 the soil as calcium hydrate. The falsity of this assumption 
 is evident in view of the fact that calcium carbonate, if 
 placed even in distilled water, is somewhat soluble and will 
 
278 
 
 FERTILIZERS 
 
 cause it to give an alkaline 
 reaction. Furthermore, car- 
 bonic acid, which is always 
 present in the rainfall and 
 in the soil water, increases 
 decidedly the alkaline reac- 
 tion, by virtue of forming 
 calcium bicarbonate. Again, 
 salts of lime formed by other 
 weak acids may themselves 
 give an alkaline reaction in 
 water. This experiment by 
 Heiden has been widely cited 
 by various writers as a rea- 
 son why hydrated or burned 
 lime should not be applied 
 to soils, yet had they taken 
 the pains to investigate the 
 circumstances, it would have 
 been found that the con- 
 clusion of Heiden was not 
 justified by the experimen- 
 tal method which was fol- 
 lowed. 
 
 The - bearing of the 
 Maryland station experi- 
 ments. — ■ Still another ex- 
 periment, made at the 
 Maryland agricultural ex- 
 periment station, has been 
 generally cited in the 
 United States as showing 
 great superiority of calcium 
 
LIME AND ITS RELATION TO SOILS 279 
 
 carbonate over slaked or burned lime. In this case the 
 soil was admittedly deficient in both available potash and 
 phosphoric acid, and it was only in certain of the eleven 
 years covered by the experiment that any fertilizer was 
 applied, although its need was indicated by the small size 
 of the crops which were harvested. In this case marl 
 and ground oyster shells were compared with stone lime 
 and burned oyster shells, as well as with burned magnesia. 
 It appears, however, upon an investigation of the circum- 
 stances that the total quantity of marl probably contained 
 from 400 to 450 pounds of potash and approximately 
 48 pounds of phosphoric acid, and that these substances 
 may readily have become limiting factors in connection 
 with the yields. In fact, it seems probable, in the light of 
 this circumstance, that enough available potash and phos- 
 phoric acid may have been secured by the crops from the 
 marl, in many or all of the cases, to have accounted for 
 the greater yields which it often produced. As concerns 
 ground oyster shells, they often contain nearly .5 per cent 
 of nitrogen and over .1 per cent of phosphoric acid, which 
 may have given them some advantage over the burned 
 lime. 
 
 The fine matter associated with the marl used in the 
 Maryland experiments may have improved the physical 
 character of the soil. It is especially significant, likewise, 
 that in some cases the burned magnesia and burned oyster 
 shells actually gave larger crops than at least the ground 
 oyster shells. It appears probable, also, that the Maryland 
 plots were not, in all cases, sufficiently uniform in char- 
 acter to justify some of the conclusions which have been 
 drawn by others from the experiment. In view of this fact, 
 and of the other circumstances mentioned, undue weight 
 has apparently been attached to these results as a basis 
 
280 FEETILIZERS 
 
 for discrimination against slaked or burned lime. In 
 fact, Director Patterson, who made the experiment, still 
 recommends slaked lime for many agricultural purposes. 
 
 Views of certain eminent European authorities. — In 
 conclusion it should be said that such eminent European 
 authorities as Deherain in France, and Orth in Germany, 
 though fully familiar with the dangers which may arise 
 from the unintelligent and inordinate use of burned or 
 slaked lime, nevertheless, recognize the great agricultural 
 value of these forms of lime in specific cases, when used in 
 
 No lime Lime as top-dressing in Lime harrowed in 
 
 spring after seeding before seeding 
 
 Fig. 35. — Timothy. All Seeded the Same Autumn. 
 
 The lime in both cases was from the same lot, and was weighed out at the 
 
 same time. 
 
 reasonable amounts, and under ordinary conditions of 
 culture. 
 
 441. The penetration of lime into soils. — One of the 
 usual recommendations regarding lime is to harrow it 
 into the surface of the soil, for the reason that it tends to 
 work downward. There can be no doubt but that the 
 various forms of lime will be carried downward to a con- 
 siderable extent both by mechanical washing and in solu- 
 tion as bicarbonate and otherwise, especially in soils 
 which are sandy and open, and which are relatively de- 
 ficient in vegetable matter. 
 
LIME AND ITS RELATION TO SOILS 281 
 
 On upland soils which are very compact, like certain 
 silts and clays or fine soils containing large quantities of 
 vegetable matter in advanced stages of decomposition, the 
 chance for the descent of lime to the lower levels, excepting 
 as it leaches through as nitrate, is very small, unless ex- 
 cessive amounts are used. This has been well illustrated 
 by the experience of Coville, who attempted to introduce 
 lime-water into the lower levels of a soil rich in vegetable 
 matter, only to find that all of the lime was held in a com- 
 paratively thin layer of the surface soil. 
 
 Another striking example of lime being retained in the 
 surface soil is afforded in connection with the renovation 
 of some of the acid peat (hoch-moor) soils of northern Ger- 
 many. After liming, and other suitable treatment, these 
 soils bore good crops for a few years, only to be followed 
 later by frequent serious failures. Subsequent investiga- 
 tion showed that this failure was due to the fact that the 
 upper layer of soil had become so thin, as a result of the 
 decompositions induced by the lime and by the system of 
 drainage, that the crops suffered from drought by virtue 
 of the fact that their roots did not penetrate to a sufficient 
 depth to avail themselves of the permanent water supply. 
 In fact, the lime had been of little or no value as a soil 
 amendment below the level to which it was originally in- 
 troduced, and the unlimed acid peat beneath was such an 
 inhospitable medium that the plant roots would not pene - 
 trate it to any practical extent. The unfortunate condition 
 was corrected by subsoiling with a plow carrying knife at- 
 tachments in the rear, and lime in a hopper on the beam, 
 by which means lime was incorporated with the lower 
 levels of the soil, after which the conditions for plant 
 growth were again found to be favorable. 
 
 The fact that plant roots will not readily penetrate an 
 
282 FERTILIZERS 
 
 inhospitable medium has been recently demonstrated by- 
 Reed in connection with some ingeniously devised experi- 
 ments conducted in the laboratory of the Bureau of Soils 
 of the United States Department of Agriculture. 
 
 442. The expulsion of ammonia from soils as a result 
 of liming. — Experiments by Boussingault and others 
 are often cited to show that so long as lime remains in the 
 soil, in a caustic state, the formation of ammonia pro- 
 gresses. Observations are also on record showing that 
 
 Limed Unlimed Limed Unlimed 
 
 Nitrate of soda Sulfate of ammonia 
 
 Fig. 36. — Alfalfa under Treatment. 
 
 All fertilized alike with potash and phosphoric acid. A like amount of 
 
 nitrogen used in each case. 
 
 actual losses of ammonia from limed soils have been noted 
 in laboratory experiments ; and likewise in fields, after 
 heavy liming. In most pot experiments, however, the 
 proportion of lime to soil will be found to have been far 
 greater than those existing in practical field operations; 
 and even the applications of lime in the field were usually 
 excessive and beyond what would be employed in rational 
 agricultural practice. At all events, on all ordinary clay, 
 silt, or loam soils the absorptive and chemical combining 
 power of the soil for ammonia is so great that no material 
 losses need be feared, wherever only reasonable applica- 
 
LIME AND ITS RELATION TO SOILS 283 
 
 tions of slaked or burned lime are made. This has been 
 fully established at the experiment station of the Rhode 
 Island State College, by both pot and field experiments, 
 in connection with which applications of from 1 to 4 tons, 
 per acre, of slaked lime have been made. 
 
 It has been observed, on unlimed soil, where sulfate of 
 ammonia has been used, that ammonium salts, consisting 
 chiefly of the carbonate or bicarbonate, sometimes appear 
 on the surface as an efflorescence, some time after the 
 sulfate of ammonia is applied ; and in case the former salt 
 were formed, losses of ammonia would be expected to 
 occur. Where lime was employed, and the conditions for 
 nitrification were better, no such efflorescence has ever 
 been noticed. It therefore appears probable that there 
 are cases where the retention by the soil of the nitrogen 
 applied as ammonia, may be actually furthered by the 
 employment of lime. 
 
 What has preceded illustrates the danger of generalizing 
 from laboratory experiments, in which quite unusual 
 conditions often prevail, or from field experiments in 
 which excessive applications of lime have been used, as to 
 what will transpire under the usual and normal conditions 
 of farm practice. Nevertheless, such data serve as a 
 constant and useful warning to those who must deal with 
 very open, sandy soils, to the effect that there may be 
 danger of serious direct loss of ammonia if either slaked 
 or burned lime is used on them in excessive amounts. 
 
 443. The influence of lime on nitrification. — The 
 influence of lime in promoting nitrification is now too well 
 understood to require more than mere mention. It, or 
 some other base, is essential to combine with the nitric 
 acid as produced, and hence to prevent the uncombined 
 nitric acid from accumulating to such an extent as to 
 
284 FERTILIZERS 
 
 inhibit the further action of the nitrifying organisms. 
 For this purpose slaked lime, burned lime, or carbonate 
 of lime may be used ; although if either slaked or burned 
 lime is employed, care should be taken not to use excessive 
 quantities, for large amounts of slaked or caustic lime 
 may check nitrification for a time. Such an apparent 
 delay of the process of nitrification, for about ten days, 
 resulted in one instance from the use of four tons of slaked 
 lime, per acre, at the agricultural experiment station of 
 the Rhode Island State College, on a good silt loam soil. 
 
 Unlimed Limed Unlimed Limed 
 
 Sulfate of ammonia Nitrate of soda 
 
 Fig. 37. — Chicory ttnder different Treatments. 
 
 All fertilized alike with potash and phosphoric acid. A like amount of 
 
 nitrogen was used in each case. 
 
 It was noted, however, that no such delay followed the use 
 of one ton of slaked lime per acre. At the end of the ten 
 days the plants, in the first case, practically all recovered 
 their normal appearance and made vigorous growth within 
 forty-eight hours after the first sure signs of improve- 
 ment were noticed. This improvement was doubtless 
 coincident with the time when, by natural carbonation 
 in the soil, the alkalinity of the lime had been reduced 
 below the point where it could check the development 
 of the nitrifying organisms. This experience suggests 
 the experiments by earlier English investigators who 
 
LIME AND ITS RELATION TO SOILS 285 
 
 found that nitrification would not progress in undiluted 
 urine until the alkalinity was lessened by the addition of 
 calcium sulfate. This reacted with the ammonium car- 
 bonate to form the essentially neutral salts, ammonium 
 sulfate and calcium carbonate. 
 
 It was found by Kellerman and Robinson that the ad- 
 dition of calcium carbonate to a sandy loam soil was 
 favorable to nitrification up to a limit of 2 per cent, or 
 to a far greater limit than would ever be applied to agri- 
 cultural soils. The application of magnesium carbonate, 
 however, in excess of 0.25 per cent positively inhibited 
 the action of the nitrifying organisms. 
 
 444. Effect of calcium and magnesium carbonates on 
 ammonification. — Experiments by Lipman 1 have shown 
 that, when mixed with soil, calcium carbonate depressed 
 the formation of ammonia from cotton-seed meal, but 
 stimulated it in the case of dried blood ; whereas with 
 magnesium carbonate the result was exactly the opposite. 
 This may have been due to the difference in the relative 
 calcium and magnesium content of the blood and of the 
 cotton-seed meal, whereby the relation of the two was made 
 favorable in one instance, and unfavorable in the other, 
 to the vegetative growth of the ammonifying organisms ; 
 as noted by Loew not only for certain lower organisms, 
 but also for the higher agricultural plants. It has been 
 suggested by Lipman that this difference in the action of 
 the two carbonates upon organic matter of different 
 kinds may explain the reason why the effect of magnesian 
 lime is good on some soils and poor on others ; also why 
 where the magnesian lime fails, the purer lime is often help- 
 ful. Such practical differences in the action of the two 
 carbonates as arise in farm practice may, however, not 
 
 1 Centralb. f. Bakt., II Abt., 30 (1911), 173, 174. 
 
286 FERTILIZERS 
 
 only be due to the indirect effects suggested by Lipman 
 and others, whereby more or less nitrogen is rendered 
 available to the plants, but it may also be due to a direct 
 physiological effect upon the agricultural plants themselves, 
 which, according to Loew and his various co-workers, is 
 often a very important factor in plant growth. 
 
 Recent investigations by Gile in Porto Rico appear to 
 show that much wider lime-magnesia ratios may exist, 
 without causing injury to certain plants, than the conclu- 
 sions of Loew and his fellow-workers would indicate. 
 
 445. General ideas as to the indirect manurial action 
 of lime. — Lime has long been looked upon, whether ap- 
 plied as hydrated, air-slaked, or fully carbonated lime, 
 as a liberator of potash in the soil. This has been sup- 
 posed to be due chiefly to mass action, whereby it may 
 replace other bases in the zeolites and other similar com- 
 pound silicates. Lime has also been shown by Morse and 
 Curry l to increase the amount of potash freed, even from 
 feldspathic and other potash-bearing minerals. 
 
 446. Results with sodium and magnesium salts il- 
 lustrate how lime acts indirectly. — An excellent illus- 
 tration of a very similar liberating effect of magnesium 
 and sodium is furnished by the experiments at the Roth- 
 amsted station in England in connection with the wheat 
 crop. These results are given by Hall from 1852 to 1901 
 inclusive. Sodium sulfate, potassium sulfate, and mag- 
 nesium sulfate were added singly to separate plots of land ; 
 to one plot all three were added, and a fifth plot was in- 
 cluded from which all were omitted. In the course of the 
 first ten years potassium sulfate gave smaller yields than 
 any of the other sulfates, but where all were omitted the 
 yields were markedly inferior. As time progressed the 
 
 1 Bui. 142 (December, 1909), N. H. Agr. Expt. Sta. 
 
LIME AND ITS RELATION TO SOILS 287 
 
 yields secured with sodium sulfate and with magnesium 
 sulfate became relatively less, and the result with potas- 
 sium sulfate in the subsequent decades of the experiment 
 approached somewhat closely those secured with the 
 combination of all three sulfates. Bearing in mind the 
 recent work of Hart and Peterson, 1 it might be thought 
 that these sulfates had been helpful by virtue of supplying 
 additional sulfur to the plants, rather than as a result of 
 their having liberated potash. If, however, such need of 
 sulfur had existed, it would have been expected that where 
 it was applied the percentage in the ash of the crop would 
 have been increased, which was not the case. It must, 
 however, be recognized that this is not always the case 
 with nitrogen and perhaps not with other of the necessary 
 elements. In all cases, nevertheless, the potash percentage 
 in the ash of the crop was materially increased. The 
 per cent in the ash in the case where no sulfates were 
 added was 9.91 ; the respective percentages found upon 
 the addition of sodium sulfate and of magnesium sulfate 
 were 14.68 and 14.87 ; whereas, as a result of the use of 
 potassium sulfate alone the potash in the ash rose to 23.28 
 per cent. With all three sulfates it amounted to 25.89 
 per cent. These changes were not accompanied by in- 
 creases in the percentages of either soda or magnesia. 
 
 447. Fixation of potash after liberation by lime. — 
 Notwithstanding that, in agreement with others, lime 
 was found by Morse and Curry to have a marked solvent 
 action upon the potash of feldspars, yet in the presence of 
 considerable clay the potash was not found to have been 
 rendered soluble in water. This was probably due to its 
 having been fixed by the zeolitic compounds of the clay as 
 fast as it was freed from the feldspar. This possibility is 
 
 1 Research Bui. 14 (April, 1911), Wis. Agr. Expt. Sta. 
 
288 FERTILIZERS 
 
 illustrated by experiments performed by Gerlach in which 
 he found tricalcium phosphate more or less soluble in cer- 
 tain weak acids, yet in the presence of iron and aluminum 
 hydroxids no phosphoric acid was found in solution even 
 after long-continued action. It was ascertained, however, 
 in this case, that the phosphoric acid had been transferred 
 to the iron and aluminum oxids, which fixed it as fast as 
 the acid released it from its combination with lime. It 
 appears probable, therefore, that as a result of the inter- 
 action of the lime and feldspar, in the presence of the 
 
 Limed Unlimed Limed Unlimed 
 
 Nitrate of soda Sulfate of ammonia 
 
 Fig. 38. — Chimson Clover under Treatment. 
 
 All fertilized alike with potash and phosphoric acid. A like amount of 
 
 nitrogen was used in each case. 
 
 clay, the potash of the feldspar may have passed to some 
 extent into zeolitic combinations, as a result of which its 
 subsequent availability to plants may have become greater 
 than in its original combination. It is possible also that 
 in the presence of the clay considerable lime was also 
 absorbed or fixed by zeolites directly, whereby the action 
 of the lime on the feldspar was greatly weakened. Indeed, 
 Storer states that after submitting clay to the action of 
 lime-water for a week or two, it will be found that an 
 appreciable quantity of the clay which was previously 
 insoluble in hydrochloric acid will then be dissolved, with 
 
LIME AND ITS RELATION TO SOILS 289 
 
 separation of gelatinous silica. In other words, by the 
 addition of the lime to the clay, the formation of zeolites 
 or compounds of similar character is apparently promoted. 
 
 448. Caustic lime attacks powdered quartz. — It has 
 been shown by Stoeckhardt that caustic lime attacks 
 not only precipitated silica, but also even powdered quartz 
 previously extracted with acid, forming as a result hy- 
 drated calcium silicate. 
 
 The addition of carbonate of lime to soils often increases 
 their power to hold potash, ammonia, and other bases, 
 either by chemical or physical means, or perhaps by both. 
 Furthermore, these bases may be set free again by the 
 action of the sesquicarbonate or bicarbonate of lime 
 which are continually being formed in soils stocked with 
 active (the term " active" is used to designate such calcium 
 carbonate as is not surrounded by particles of clay or 
 other matter to such a degree as to be readily protected 
 from attack by carbonic acid) carbonate of lime. 
 
 449. Losses of lime by leaching. — There are contin- 
 ual losses of lime from the soil due to various causes : — 
 
 (1) Carbonate of lime is even somewhat soluble in pure 
 water, and certain salts in the soil solution are likely to 
 increase the solvent action, as, for example, sodium chlorid, 
 sodium sulfate, and certain ammonium salts. 
 
 (2) The presence of carbonic acid carried to the soil in 
 the rainfall, formed by absorption of carbon dioxid from 
 the air, and produced by the decomposition of vegetable 
 and animal matter in the soil, insures the gradual forma- 
 tion of calcium sesquicarbonate and of calcium bicarbon- 
 ate which may pass in some cases to a certain extent into 
 the drainage water. The solubility of calcium carbonate 
 has been shown to increase, at least within certain limits, 
 with the amount of carbonic acid in the solution. 
 
290 FERTILIZERS 
 
 (3) In the nitrification of manures, fertilizers, and of 
 plant or animal residues in the soil, considerable calcium 
 nitrate is formed which, not being held readily by the 
 soil, is likely to be lost in the drainage unless the nitric 
 acid therein is taken up by growing crops. At most 
 seasons of the year and under favorable soil and cultural 
 conditions, excepting in the case of a long-continued and 
 excessive rainfall, there is but little loss by this means. 
 
 (4) A considerable depletion of lime results in soils from 
 the use of sulfate of potash, or sulfate of magnesia, but 
 more especially from application of potassium, sodium, 
 and magnesium chlorids, since the resulting calcium 
 chlorid is far more soluble than calcium sulfate. Further- 
 more, in case the soil is well stocked with vegetable matter 
 and it becomes so wet as to temporarily exclude the air, 
 calcium sulfate may be reduced to calcium sulfid, which 
 in contact with carbonic acid may be decomposed into 
 hydrogen disulfid and calcium carbonate, whereby some 
 carbonate of lime is regenerated in the soil. 
 
 (5) Other salts of lime are also somewhat soluble and 
 may in consequence add to the losses by drainage. 
 
 It is on account of these and other tendencies to loss 
 of lime by natural drainage, and on account of the trans- 
 formation of the calcium carbonate into other chemical 
 combinations in the soil, that care must be taken to insure 
 in soils at all times a small supply of " active " carbonate 
 of lime. 
 
 450. Coarsely ground limestone compared with fine 
 limestone and marl. — It is on account of the continual 
 loss of lime from the soil by drainage that most of the soils 
 of the humid regions which are formed from conglomer- 
 ates, granite, gneiss, certain shales, schists, and sand- 
 stones, are usually deficient in lime. For the same reason 
 
LIME AND ITS RELATION TO SOILS 291 
 
 soils of limestone regions lying even but a few feet above 
 marl, chalk, or limestone beds often become sufficiently 
 exhausted of their carbonate of lime to require its supply 
 to the surface soil. 
 
 It must be obvious from what has been said that the 
 coarser the particles of lime added to the soil, the longer 
 some of them will remain as calcium carbonate, or, in 
 other words, the longer some effect of a given application 
 
 No lime Ground magnesian limestone Ground limestone 
 
 Fig. 39. — Alfalfa Tbeatment on Farm. 
 
 All fertilized alike with potash and phosphoric acid. Quantities of 
 lime having the same total neutralizing value were used in each case. 
 On certain other soils in the same State, ground magnesian limestone 
 was found to be superior to the ordinary ground limestone. 
 
 will endure. It is, however, false philosophy to assume 
 that the lime which endures longest in the soil is neces- 
 sarily either the most efficient or the most economical. 
 It is, nevertheless, possible that there is a limit of fineness 
 which permits of the preparation of ground limestone in 
 a single grinding operation, a high percentage of which 
 will pass a sieve with from 30 to 60 meshes to the linear 
 inch, at such low cost that it is better economy to use 
 more of the coarser material than a smaller quantity 
 ground to a greater degree of fineness. If, in each case, 
 
292 FERTILIZERS 
 
 the same amount of material, passing a 30 or 50 mesh 
 screen, can be secured at the same price, the still coarser 
 associated material will cost nothing, and hence the pur- 
 chaser might do better, if the transportation charges were 
 low, to buy the coarser product. 
 
 In other cases it may be better to use less of a fine, 
 readily available, and efficient product, and to repeat the 
 application at more frequent intervals, than to buy, for 
 a larger sum of money, coarser material which, even though 
 some of it will remain in the soil longer, will nevertheless 
 tie up a large cash investment for a longer period of time. 
 No definite rule can therefore be applied to these cases, 
 since the fineness and character of the product, the rate 
 of interest, the character of the soil, the freight charges, 
 the cost of hauling by team, and other factors must de- 
 termine the choice of the purchaser in individual cases. 
 
 451. Concerning the practical use of lime. — Burned 
 lime, finely ground or crushed, may be used at rates rang- 
 ing from a quarter of a ton on certain light soils to two 
 and one-half tons on extremely acid soils which are rich 
 in humus, capable of immediate extraction with ammo- 
 nium hydroxid. A third more, in weight, of air-slaked or 
 hydrated lime may be used under the same circumstances, 
 or somewhat more than double the quantity of ground 
 limestone or marl. 
 
 Care should be taken to learn from small experimental 
 plots about what quantities of lime are necessary, on a 
 given soil, to insure success with the special crops to be 
 grown ; and this amount will often be found to be far short 
 of the total " lime requirement," as indicated by certain 
 quantitative laboratory methods. 
 
 Excessive liming is something to be especially avoided, 
 for the natural tendency of farmers is to carry it to ex- 
 
LIME AND ITS RELATION TO SOILS 293 
 
 tremes as soon as the advantages from the use of lime have 
 once been fully recognized. 
 
 On rocky pastures which cannot be plowed, lime must 
 obviously be applied to the surface ; and for this purpose 
 ground limestone, or, preferably, shell marl or wood-ashes, 
 are much to be preferred to burned or slaked lime. 
 
 On mossy lands, in bad general condition, small appli- 
 cations of some form of lime may be made to advantage 
 just before plowing; but the chief part of the application 
 should be made afterward, when it should be immediately 
 
 4» «•* m w 
 
 Limed Unlimed Limed Unlimed 
 
 Nitrate of soda Sulfate of ammonia 
 
 Fig. 40. — Watermelons variously Treated. 
 
 All fertilized alike with potash and phosphoric acid. A like amount of 
 
 nitrogen was used in each case. 
 
 and thoroughly harrowed into the soil. In all such cases 
 the principle should be borne in mind that the nearer a 
 particle of lime can be brought to each particle ' of soil, 
 the better will be the result. 
 
 For most purposes, in ordinary farm practice the har- 
 rowing of the lime into the soil after plowing is to be rec- 
 ommended, though on land which cannot be plowed, car- 
 bonate of lime may be spread broadcast on the sod in 
 order to bring in clover and certain nutritious grasses 
 which may otherwise fail to thrive. 
 
 452. Pure lime compared with magnesian lime. — 
 Instances are on record, as in the experiments by Pat- 
 
294 ' FERTILIZERS 
 
 terson, 1 in which burned magnesia in certain instances has 
 given better results than burned lime, and there are, for 
 example, certain soils, as in parts of New Jersey and else- 
 where, upon which magnesian lime gives generally better 
 results than pure lime. The reverse is also true in still 
 other localities in New Jersey and elsewhere in other states. 
 This is usually due to the presence in the soil of relatively 
 much greater quantities of magnesia than of lime, and in 
 such cases the use of highly magnesian lime may some- 
 times become objectionable. 
 
 Within a few years new and important light has been 
 shed on the whole question by Loew and his various co- 
 workers, which will be discussed in full in considering 
 magnesia. 
 
 As a general rule it is at least erring on the safe side if 
 one avoids liming repeatedly with a highly magnesian 
 lime, and uses, alternately, a purer grade of lime. 
 
 !Bul. 110, Md. Agr. Expt. Sta. (1906), 13-21. 
 
CHAPTER XX 
 
 LIMING IN ITS RELATION TO PLANTS 
 
 The subject of liming is just as important in its rela- 
 tion to plants as in its relation to soils and fertilizers, and 
 in this respect the complexity of the whole question be- 
 comes increasingly great with each new research which is 
 conducted. 
 
 453. Plants may transform lime compounds. — The 
 function of plants in aiding in the transformation of 
 one lime compound into another suggests itself by the 
 fact that lime is taken up abundantly by common sorrel 
 from soils in which carbonate of lime is practically absent. 
 When once within the plant, the lime performs the valuable 
 function of neutralizing and removing from the circula- 
 tion, as insoluble calcium oxalate, some of the oxalic acid, 
 the excessive accumulation of which is toxic even to the 
 plant in which it is produced. This compound in its 
 turn, like calcium acetate and other organic calcium salts, 
 is readily broken up into calcium carbonate in the soil in 
 the course of the normal processes of decay ; thus actually 
 tending in a slight degree to correct for other plants the 
 soil conditions which are unfavorable to them, but which 
 in no way inhibit the luxuriant growth of the common 
 sorrel. A study of other plants with this feature in mind 
 will reveal other possibilities of a similar character. 
 
 454. Miscellaneous effects of lime on plant diseases. — 
 If lime is applied to acid soils, it creates a condition far 
 
 295 
 
296 FERTILIZERS 
 
 more favorable to development of potato "scab " than that 
 which existed at the outset. This action is, however, by 
 no means confined to lime, since sodium carbonate, barn- 
 
 Limed Unlimed . Limed Unlimed 
 
 Nitrate of soda Sulfate of ammonia 
 
 Fig. 41. — Rye under Treatment. 
 
 All fertilized alike with potash and phosphoric acid. A like amount of 
 
 nitrogen was used in each case. 
 
 yard manure, or other substances which are of an alkaline 
 character have the same effect. For this reason lime 
 should usually be introduced into a crop rotation after, 
 rather than preceding, the potato crop. It is also impor- 
 
LIMING IN ITS RELATION TO PLANTS 297 
 
 tant in all cases that the seed tubers should be treated with 
 corrosive sublimate solution, as proposed by Bolley, or 
 with formalin, in order to destroy any germs of the disease 
 which may be present upon them. 
 
 The dry spot of oats has also been recently observed in 
 Europe to occasionally follow the use of lime. A some- 
 what similar or identical disease, or a possible disturbance 
 of physiological function of oat plants, has been observed 
 on silt loam soil in occasional years at the agricul- 
 tural experiment station of the Rhode Island State Col- 
 lege. The evidence thus far at hand points rather to a 
 disturbance of physiological functions. It is notable 
 that the difficulty seems to depend, nevertheless, in a great 
 measure upon the prevailing climatic conditions, for in 
 certain seasons no injury has been observed. 
 
 It was thought at first in Europe that the difficulty was 
 confined to the moor (peat) soils, but it is now recognized 
 as occurring also on sandy and clayey soils ; and Hudig 1 
 believes it to be due to changes in the composition of the 
 humus brought about by repeated applications of the lime, 
 or by other physiologically alkaline fertilizers. 
 
 The use of excessive amounts of lime or of other alkaline 
 substances has been found to encourage a disease of to- 
 bacco known as " tobacco root rot " 2 which is caused 
 directly by a fungus (Thielavia basicola), the development 
 of which may be hindered by the use of acidic fertilizers. 
 It r has been suggested also that similar treatment may 
 aid in combating certain diseases of the ginseng. 
 
 A striking illustration of the lessening of disease by the 
 use of lime is afforded by the " club-foot," " aubury," or 
 
 i E. S. R., 25, 724; also Landw. Jahrb., Ifi (1911), 613-644. 
 2 Circ. No. 7, Bureau of Plant Industry, U. S. Dept. of Agr. (1908) 
 By Lyman J. Briggs. 
 
298 
 
 FERTILIZERS 
 
 Air-slaked lime Unlimed 
 
 Fig. 42. — Treatment for Potato Scab. 
 
 Complete fertilizer in both cases. 
 
 Calcium sulfate Calcium chlorid 
 
 Fig. 43. — Treatment for Potato Scab. 
 Complete fertilizer in both cases. 
 
LIMING IN ITS RELATION TO PLANTS 299 
 
 " finger-and-toe " disease of the cabbage, turnip, and other 
 related plants of the Cruciferce family. This is accomplished 
 by the employment of especially heavy applications of 
 caustic lime immediately following a badly diseased crop, 
 and again just before the growing of crops subject to the 
 disease. 
 
 455. Lime in connection with potato scab. — The ef- 
 fect of lime in encouraging potato scab has been mentioned 
 briefly elsewhere, but the subject is of such importance 
 that it requires more than passing notice. 
 
 Earlier ideas. — Prior to the year 1891 when Thaxter l 
 discovered that potato scab was caused by a fungus 
 (Oospora scabies Thaxt.), many observations had been 
 made in Germany and elsewhere upon its appearance. 
 Its occurrence had previously been attributed to lime and 
 to many other substances, on the ground that they caused 
 an irritation or injury to the surface of the tuber, and that 
 in the attempt to recover from the injury the characteristic 
 growth of scab devleoped. 
 
 The work of Thaxter. — The laboratory investigations 
 of Thaxter were supplemented by him by field trials of 
 various substances for one season, in the course of which 
 he found 60 per cent of scab when broken plaster and 
 cement were used in the hill, whereas in alternate hills 
 in which mixed fertilizer was used but 6 per cent of scab 
 was found. Among other materials Thaxter also employed 
 wood-ashes in the same manner as the broken plaster and 
 cement. In this case but 7.5 per cent of scab resulted, 
 whereas in the alternate hills without wood-ashes but with 
 the mixed fertilizer 12.5 per cent of scab was observed. 
 From the foregoing it is obvious that the results furnished 
 no conclusive evidence of lime having promoted the devel- 
 
 1 An. Rpt. Conn. Agr. Expt. Sta. (New Haven), 153-160. 
 
300 
 
 FERTILIZERS 
 
 Calcium carbonate Calcium ox 
 
 Fig. 44. — Treatment for Potato Scab. 
 Complete fertilizer in both cases. 
 
 Calcium acetate 
 
 Fig. 45. — ■ Treatment for Potato Scab. 
 Complete fertilizer in both cases. 
 
 Wood- 
 
LIMING IN ITS RELATION TO PLANTS 
 
 301 
 
 opment of scab, since they were negative with wood-ashes, 
 which doubtless supplied much more carbonate of lime 
 than was present in the broken plaster and cement. 
 
 The work at the Rhode Island experiment station. — 
 Upon the conclusion of Thaxter's work the matter was 
 carefully investigated for a period of four years at the ex- 
 periment station of the then Rhode Island Col ege o 
 Agriculture and Mechanic Arts 1 with the result that 
 slaked lime, wood-ashes, calcium carbonate, calcium oxa- 
 late, calcium acetate, sodium carbonate, and barn-yard 
 manure were all found to encourage the development of 
 potato scab to a most serious extent, in case the causative 
 fungus was present on the « seed » tubers or was already 
 existent in the soil. On the other hand, calcium sulfate, 
 calcium chlorid, sodium chlorid, and oxalic acid either 
 failed to increase the scab or materially lessened it. By 
 the use of a complete fertilizer, even with badly scabbed 
 " seed " tubers, little or no scab ensued on soil which was 
 quite acid. It was conclusively shown, also, m cases m 
 which the soil was already badly contaminated by the 
 fungus, and where it had been made favorable to potato 
 scab by the use of alkaline manures or amendments, that 
 treatment of the " seed " tubers exerted no appreciable 
 protective influence against scab. 
 
 Owing to the fact that in Thaxter's laboratory experi- 
 ments the fungus failed to thrive well, not only on very 
 acid, but also on very alkaline, media, it seems likely 
 that the reason the wood-ashes failed to encourage scab, 
 in his original field experiment, was that they were 
 probably employed at rates far in excess of what would be 
 usually applied to land, thus creating a strongly alkaline 
 reaction, which may be just as protective against scab 
 
 i Bulletins 26 (1893), 30 (1894), 33, (1895), and 40 (1896). 
 
302 FERTILIZERS 
 
 as a condition of extreme acidity. This explains also 
 the reason why broken plaster and cement should have 
 encouraged scab, for the active lime therein must have 
 been relatively too small to produce such a degree of 
 alkalinity as would have been produced by the combined 
 action of the carbonates of lime, magnesia, potash, and 
 soda, all of which may have been present in the wood- 
 ashes. 
 
 456. Lime may be used and potato scab avoided. — 
 Notwithstanding the tendency of lime to promote potato 
 scab, it has been used periodically at the experiment sta- 
 tion of the Rhode Island State College in several crop 
 rotations in quantities amounting in the aggregate to 
 about 3200 pounds of calcium oxid in a period of about 
 twenty years, and yet without practical injury to the 
 potato crops from scab. In this case, however, the lime 
 is applied in the rotations immediately following the po- 
 tato crops, at intervals of from three to six years, and the 
 tubers are always treated with formalin or with corrosive 
 sublimate solution before they are planted. The impor- 
 tance of these precautions is obvious, in view of the fact 
 that in certain of the experiments in Rhode Island, in 
 which they were not taken, the scab fungus has survived 
 saprophytically an interval of seventeen years without an 
 intervening potato crop. 
 
 457. Lime may cause injury to pineapples. — It has 
 been reported by Gile x that when lime is present in sandy 
 soils, in excess, it may be a cause of pineapple chlorosis. 
 In such cases treatment of the leaves and soils with iron 
 salts, though said not to be feasible from an economic 
 standpoint, proved to be an effective antidote. The 
 treatment of the leaves is in accord with recent experi- 
 
 1 Porto Rico Agr. Expt. Sta., Bui. 11. 
 
LIMING IN ITS RELATION TO PLANTS 303 
 
 ments showing that inorganic fertilizers can enter plants 
 effectively through the leaf. 
 
 458. The effect of lime on the size of potatoes. — Many 
 
 Limed Unlimed 
 
 Nitrate of soda 
 
 Limed Unlimed 
 
 Sulfate of ammonia 
 
 Fig. 46. — Oats under Treatment. 
 All fertilized alike with potash and phosphoric acid. A like amount of 
 nitrogen was used in each case. 
 
 experiments on an acid silt loam at the agricultural ex- 
 periment station in Rhode Island, covering several years, 
 have shown that liming frequently results in increasing 
 the total crops of potatoes. This effect is, however, in- 
 
304 FERTILIZERS 
 
 consequential compared with the great increase in the 
 relative per cent of large tubers, a point which is of decided 
 economic importance. 
 
 459. Liming may hasten crop maturity. — The question 
 of the influence of lime in hastening crop maturity has 
 been much debated pro and con, probably for the reason 
 that its effects are very different, depending upon the 
 character of the soil, the crop, and other attendant con- 
 ditions. 
 
 If the physical condition of a soil were injured by liming, 
 the growth of crops might be unduly prolonged; but if 
 liming were to improve the physical condition, it would be 
 expected that the maturity of the crops grown upon the 
 soil would be hastened. 
 
 If there were a lack in the soil of readily available nitro- 
 gen, phosphoric acid, or potash, at the outset, to meet 
 fully the plant requirements, the tendency would be to 
 delay growth, and hence the final maturity of the crop. 
 If, on the other hand, liming were to promote a sufficiently 
 active ammonification and nitrification, or if it were to 
 bring about a sufficient liberation of lacking mineral in- 
 gredients to meet the complete needs of the plant, without 
 material excesses, growth would follow rapidly from the 
 outset, and maturity would probably be hastened. 
 
 If a soil were very acid, and hence poorly adapted to the 
 luxuriant growth of certain plants, liming would likewise 
 be expected to hasten development and maturity. In this 
 way one may account for the marked increase in large 
 potato tubers mentioned previously. For similar reasons 
 crops of onions have been observed to ripen from two to 
 three weeks earlier on land which had been limed three 
 times in the course of fifteen years than where the land had 
 been limed but twice in the same interval. It has been 
 
LIMING IN ITS RELATION TO PLANTS 305 
 
 observed in cases where liming failed, or practically failed, 
 to increase the yield of Indian corn, that the maturity 
 was nevertheless hastened from a week to ten days. 
 
 On acid soils the effect of lime in hastening the maturity 
 of cantaloupes and of kohl-rabi has often been found to 
 be very marked. 
 
 Limed Unlimed 
 
 Nitrate of soda 
 
 Limed Unlimed 
 
 Sulfate of ammonia 
 
 Fig. 47. — Wheat under Treatment. 
 All fertilized alike with potash and phosphoric 
 acid. A like amount of nitrogen was used in each 
 
 i In case a soil were already abundantly supplied with all 
 needed forms of plant food, and large quantities of nitrates 
 were to be produced, as a result of liming, this additional 
 supply would naturally have a tendency to prolong growth 
 at the expense of maturity, just as was found by Voorhees 
 to be the case when repeated applications of nitrate of soda 
 
306 
 
 FERTILIZERS 
 
 were made to tomato plants, in contrast to a single appli- 
 cation at the outset. 
 
 460. Soils needing liming for some plants ideally 
 adapted to others. — Soils giving strong and quick re- 
 
 Limed Unlimed 
 
 Nitrate of soda 
 
 Limed Unlimed 
 
 Sulfate of ammonia 
 
 ■Fig. 48. — Barley under Treatment. 
 All fertilized alike with potash and phosphoric acid. A like amount 
 of nitrogen was used in each case. Comparisons with Figs. 41, 46, and 
 47 show that barley is more helped by liming than wheat, oats, or rye. 
 
 actions with blue litmus paper and with ammonium 
 hydroxid are frequently highly toxic to certain very sen- 
 sitive plants, even though the soils have not been fertilized 
 at all for many years with either chemical fertilizers 
 or barn-yard manure other than perhaps the occasional 
 
LIMING IN ITS RELATION TO PLANTS 307 
 
 dropping of dung by horses or cows. It is not to be sup- 
 posed that the ill effect upon certain plants is necessarily 
 due in all cases directly to soil acidity, but perhaps chiefly 
 in many cases to toxic iron compounds, toxic organic 
 substances, or other deleterious compounds accompanying 
 the lack of basic substances, or arising in consequence 
 thereof, which are oxidized, catalysized, or otherwise de- 
 stroyed as a result of the application of lime. 
 
 461. Details concerning the lime requirements of dif- 
 ferent plants. — It is not safe in any event to generalize 
 from experimental results secured with one, or even with 
 several, plants in regard to the lime requirements of other 
 plants in their relation to the soil. This is well illustrated 
 by the fact that a soil rendered so toxic by the long-con- 
 tinued application of ammonium sulfate as to absolutely 
 inhibit the growth of the poppy, lettuce, beet, canta- 
 loupe, asparagus, cress, onion, barley, clover, and a whole 
 series of other agricultural and ornamental plants will yet 
 produce better plants of the common sorrel, cranberry, or 
 Silene orientalis than it will after the condition, so highly 
 unfavorable to most plants, had been corrected by liming. 
 With only the latter plants in mind, and provided one had 
 not experimented with others, the natural assumption 
 might be that agricultural soils are never so acid or so 
 charged with toxic substances as to interfere with the 
 growth of plants, for the worse the condition becomes for 
 certain plants, within reasonable limits, the better certain 
 others seem to thrive. Similarly, on the other hand, cer- 
 tain plants are best suited by conditions of alkalinity or 
 salinity which are totally destructive to the great majority 
 of agricultural plants. 
 
 On account of a lack of sufficient appreciation of these 
 conditions, the agricultural press and even scientific pub- 
 
308 FERTILIZERS 
 
 lications often contain statements to the effect that legumes 
 are in great need of liming, in order that they may develop 
 root nodules and properly assimilate atmospheric nitrogen. 
 Nevertheless, the Southern cowpea, serradella, and certain 
 of the lupines are likely to be injured by heavy liming. 
 Other legumes may possibly be injured under the same 
 conditions, whereas the alfalfa and winter vetch suffer 
 seriously, for lack of lime, even where clover will still grow 
 with moderate success. 
 
 Not only the lupines (Lupinus), but also the beans 
 (Phaseolus), differ widely among themselves as to their 
 requirements for lime in its amendatory capacity. 
 
CHAPTER XXI 
 
 GYPSUM AND WASTE LIME FROM INDUSTRIES 
 
 Recently gypsum has been employed in the United 
 States to a smaller extent than formerly, whereas the use 
 of ground limestone, burned lime, slaked lime, and waste 
 lime from certain industries has increased. 
 
 462. Early use of gypsum. — Gypsum (land plaster or 
 calcium sulfate) has been used as a fertilizer since the time 
 of the earliest Greek and Roman writers. Much mystery 
 surrounded its action in earlier times, which has been re- 
 moved by modern discoveries in agricultural science. It 
 is now available as ground gypsum and as a by-product 
 of the manufacture of double superphosphate. 
 
 463. The source of some of the gypsum in soils. — In 
 certain localities considerable calcium sulfate is present in 
 soils naturally, and since the advent of superphosphates it 
 has been added in that form to the land in considerable 
 quantities, with but little thought on the part of the user 
 that it was present in the usual commercial fertilizer 
 which he was applying. 
 
 Gypsum has also been added to soils incidentally, in 
 some cases, in kainit, which is used by itself or as a fre- 
 quent constituent of ready mixed commercial fertilizers. 
 
 The effect of gypsum and lime on clover and other plants. 
 — In Europe, generally, gypsum has long been considered 
 as a specific for clover ; and in many cases it has been 
 found to give much better results than lime. Indeed, 
 
 309 
 
310 
 
 FERTILIZERS 
 
 Storer l cites several such 
 cases and mentions in the 
 same connection that Gas- 
 parin found it to work well 
 on a soil containing 20 per 
 cent and more of lime. 
 
 In experiments at the 
 agricultural experiment 
 station of the Rhode Is- 
 land State College it was 
 found, on an acid silt loam 
 soil, that, notwithstanding 
 a striking gain in beets and 
 clover resulting from the 
 use of gypsum, the employ- 
 ment of the same quantity 
 of calcium oxid in air- 
 slaked lime gave far better 
 results. 
 
 In order to throw light 
 upon other similar discrep- 
 ancies in the use of these 
 substances, it should be 
 pointed out that Gasparin 
 was dealing with a soil well 
 supplied with lime, in whi ch 
 the general conditions were 
 not unfavorable to the 
 growth of the particular 
 crop concerned, whereas in 
 the experiment made in 
 
 1 Agriculture, etc., 
 (1897), 326. 
 
 Vol. 
 
GYPSUM AND WASTE LIME FROM INDUSTRIES 311 
 
 Rhode Island the soil was a silt loam essentially devoid 
 of carbonate of lime and so deficient in bases as to 
 quickly and intensely redden blue litmus paper and to 
 yield large quantities of humus (" matiere noire " of 
 Grandeau) upon extraction with dilute ammonium 
 hydroxid, without previous extraction with hydro- 
 chloric acid. It was also shown that applications of 
 sodium carbonate, potassium carbonate, and burned 
 magnesia very largely corrected the condition of this soil 
 for beets and other plants, but that the corresponding sul- 
 fates were of little or no avail. It is evident, therefore, 
 that in Gasparin's experiment neutralization of the soil 
 was not needed, and gypsum was helpful probably chiefly 
 because of the liberation of potash or possibly by virtue 
 of supplying sulfur, both of which clover greatly needs. 
 Gypsum may nevertheless also have been useful in liber- 
 ating magnesia and phosphoric acid or in counteracting 
 an improper relation between lime and magnesia, if such 
 existed. 
 
 The possibility of some indirect action in the experi- 
 ment by Gasparin is well illustrated by experiments by 
 Boussingault in which the application of gypsum resulted 
 in raising very greatly, not only the percentage of lime in 
 clover, but also the content of potash, magnesia, phos- 
 phoric acid, and sulfuric acid. 
 
 In the Rhode Island experiment generous applications 
 of complete fertilizer were made in both cases, which 
 would naturally have lessened any benefit arising from the 
 possible liberation of plant food ingredients of the soil. 
 
 464. Gypsum poorer than lime on acid soils. — The 
 chief factor causing the superior action of the slaked lime 
 in Rhode Island was the fact that the prime difficulty with 
 the soil was its acidity, which the lime could neutralize at 
 
312 FERTILIZERS 
 
 once, but which the gypsum could correct but little, if at 
 all, until by possible processes of reduction some of the 
 sulfate had been transformed into calcium sulfid and this 
 in turn into calcium carbonate through the action of car- 
 bonic acid. 
 
 465. Gypsum may yield calcium carbonate in the soil. — 
 The formation of calcium carbonate from gypsum is in- 
 dicated by the following equations : — 
 
 (1) CaS0 4 + 2 C = 2 C0 2 + CaS 
 
 calcium carbon carbon calcium 
 sulfate dioxid sulfid 
 
 (2) CaS + C0 2 + H 2 = CaC0 3 + H 2 S (volatile) 
 
 calcium carbon water calcium hydrogen 
 
 sulfid dioxid carbonate sulfid 
 
 It must be remembered, however, that these changes 
 take place under anaerobic conditions, which are not 
 likely to be vigorously maintained for a great length of 
 time in fairly open, well-drained soil which is in good tilth. 
 
 466. Gypsum may furnish lime or sulfur as plant food. 
 — It is possible that cases may occur where gypsum is 
 useful by virtue of supplying either lime or sulfur to the 
 plant, in the capacity of a plant food ingredient, but in 
 general the explanation is more properly to be sought in 
 an indirect manurial action, by virtue of the liberation of 
 other plant food elements. 
 
 467. Factors determining the choice between gypsum 
 and lime. — When dealing with soils which are acid and 
 with plants readily subject to injury by such acidity or 
 by the toxic substances which often accompany it, either 
 slaked lime or calcium carbonate is likely to prove more 
 effective as a soil amendment than gypsum. In the case, 
 however, of nearly neutral, neutral, or alkaline soils, or of 
 
GYPSUM AND WASTE LIME FROM INDUSTRIES 313 
 
 plants that find therein optimum conditions, as concerns 
 their chemical reaction, it is probable that gypsum will be 
 found to act better than the other compounds of lime. 
 
 468. Gypsum as a retainer of ammonia. — Whereas 
 much weight was formerly attached to gypsum as an agent 
 for changing the ammonia of ammonium carbonate into 
 ammonium sulfate, whereby its volatilization might be 
 avoided, it has been found that much moisture is necessary 
 to the change, and furthermore the reaction is only partial 
 and even then reversible, so that the importance of gypsum 
 in this connection, under many of the conditions practi- 
 cally to be dealt with, seems to have been much overes- 
 timated. 
 
 469. Methods of applying gypsum. — For clover it has 
 generally been found to be a good practice to apply the 
 gypsum to the moist leaves when the plants are only a 
 few inches high. Similarly, it has been applied with good 
 results to potatoes by scattering it along the top of the 
 drill after the plants are well up and immediately before 
 cultivating them. It may of course be spread broad- 
 cast, and then be harrowedinto the soil, especially before 
 seeding to clover and before the planting of other crops. 
 
 470. Gypsum as an oxidizing agent. — Mention has 
 been made of the reduction of calcium sulfate to calcium 
 sulfid, and it should be recognized that in connection with 
 this process gypsum plays the role of an oxidizing agent. 
 It furnishes the oxygen for the destruction of the vege- 
 table matter, which takes place through the intervention 
 of the microorganisms of the soil. 
 
 471. Gypsum may sometimes aid nitri cation. — 
 Owing to the capacity of gypsum to react with ammonium 
 carbonate to form ammonium sulfate and calcium car- 
 bonate, it has been shown by Warrington to be effective 
 
314 FERTILIZERS 
 
 in promoting nitrification in liquid manure or in manure 
 heaps, where the reaction is too alkaline at the outset 
 for nitrification to begin. 
 
 472. Gypsum a renovator of alkaline soils. — Gypsum 
 has been shown by Hilgard and others to be an efficient 
 substance for counteracting black alkali (sodium carbon- 
 ate) in consequence of its reacting with it to produce 
 sodium sulfate and calcium carbonate, whereby the al- 
 kalinity is greatly reduced. 
 
 473. Effect of gypsum on the solubility of lime. — It 
 has been shown by Cameron and Bell 1 that the solubility 
 of gypsum is depressed in an increasing degree as the 
 amount of lime (CaO) in the solution is increased, where- 
 as with increasing amounts of gypsum in the solution the 
 solubility of lime seems to be nearly the same as in pure 
 water. 
 
 474. Gas-lime and lime from other industries. — " Gas- 
 lime," or " gas-house lime " as it is sometimes called, 
 should lie exposed to the air for some time in order to 
 effect the destruction of certain poisonous substances, 
 before it can be applied to the land with safety. The 
 lime in the processes of purifying the gas is changed very 
 largely into calcium sulfate, and hence it cannot perform 
 the same functions as slaked lime, burned lime, or calcium 
 carbonate. 
 
 The lime waste from acetylene lighting plants is essen- 
 tially hydrated lime, and it has been used agriculturally 
 with good results. The same is true of the waste lime 
 from beet-sugar factories and from other industrial works. 
 
 It is always a wise precaution to have waste factory 
 products examined by an agricultural experiment station 
 
 1 Jour. Am. Chem. Soc, 28 (1906), 1220; Bui. No. 33, Bur. of Soils, 
 U. S. Dept. of Agr. (1906) ; Jour. Phys. Chem., 11 (1907), 273. 
 
GYPSUM AND WASTE LIME FROM INDUSTRIES 815 
 
 before attempting to utilize them for manurial purposes, 
 for the reason that factory processes are subject to frequent 
 changes, and the presence of some one or more substances 
 toxic to plant life is not unusual in the residues from cer- 
 tain industries. 
 
CHAPTER XXII 
 
 MAGNESIA AS A FERTILIZER 
 
 In 1851 E. von Wolff * pointed out the beneficial effect 
 of magnesia upon plant growth, although Mulder be- 
 lieved it was merely due to its liberation of other plant 
 foods. 
 
 475. Functions of magnesia in the plant. — It was 
 shown by the work of Schmiedenberg 2 that magnesia 
 was possibly of importance in connection with the forma- 
 tion of the albuminoids. At present, however, magnesia 
 is not believed to play a direct role in connection with 
 protein formation. 
 
 According to E. von Raumer 3 magnesia performs 
 useful functions in connection with the translocation of 
 starch, though in this respect potassium is now known to 
 be particularly important. 
 
 It has been asserted by Loew and by Hilgard 4 that 
 magnesia serves in the plant as a carrier of phosphorus, 
 where, according to Hilgard, it exists as dimagnesic-hydric 
 phosphate. The fact that more magnesia is present in 
 oily than in starchy seeds, supports this view, since 
 lecithin, which is rich in phosphorus, is formed in cells 
 rich in oil. It is furthermore stated by Reed that there 
 
 i Erdmann's Jour., 51 (1851), 15. 
 
 2 Zeits. f. Physiolog. Chem., 1, 205. 
 
 3 Die landw. Vers.-Sta., 29, 279. 
 
 4 Soils, etc. (1906), 382. 
 
 316 
 
MAGNESIA AS A FERTILIZER 
 
 317 
 
 is often a very definite relation between the magnesia 
 and the vegetable oils. It is also of interest to note that 
 Ville found, when magnesia was omitted, that the yield of 
 wheat fell from 337 to 123 grains. 
 
 According to Bretfield 1 an increase in the dry weight of 
 plants is impossible in the absence of magnesia. In 
 experiments by Dassonville, 2 with magnesium sulfate, 
 
 No lime Ground magnesian limestone Slaked Lime 
 
 Fig. 50. — Alfalfa on Farm. 
 All fertilized alike with potash and phosphoric acid. Quantities of lime 
 having the same total neutralizing value were used in each case. 
 
 it was found that, though delaying the growth of certain 
 legumes at the outset, it became finally indispensable. 
 The participation of magnesia in some of the most impor- 
 tant synthetic processes of the plant is asserted by Stras- 
 burger, Noll, Schenck, and Schimper. 3 
 
 In brief, no one now questions that magnesia is essential 
 to plant growth. 
 
 476. Conflicting ideas as to the action of magnesia. — 
 According to Atterberg, 1 the compounds of humus 
 
 1 Pflanzenphysiologie (1884), 135. 
 
 2 Revue generate de Botanique, 8 (1896), 331; Abs. Jahresb. f . 
 Chem. (1896), 260. 
 
 3 A Textbook of Botany, translated by Porter (1898), 173. 
 
 Agr. 
 
318 
 
 FERTILIZERS 
 
 with lime are less soluble than those of humus and mag- 
 nesia. 
 
 It was asserted by Stutzer 2 as late as 1893 that soils 
 usually contain sufficient magnesia to meet plant require- 
 ments, yet D. Meyer, 3 for example, attaches special value 
 
 12 3 4 
 
 Fig. 51. — Treatment of Oats. 
 1. Unlimed. 2. Calcium chlorid in 1894 and 1895. 3. Same as 2, with 
 addition of caustic magnesia in 1897. 4. Same as 2, with addition of slaked 
 lime in 1897. All fertilized alike with complete fertilizer. 
 
 to magnesian lime as compared with the high calcium 
 limes, in connection with the growth of certain legumes; 
 and Larbaletrier and Malpeaux report the use of magne- 
 sium sulfate as advantageous for beets, for some years, in 
 the Department of Pas-de-Calais, France. Similar results 
 are also recorded by Stockhardt, in Saxony, and like 
 
 1 Svenska Mooskultur-foreningenstidschrift (1891), 121, 122; Abs. 
 Centralb. f. Agrik. Chem, 21, (1882), 298, 299. 
 
 2 Leitfaden der Diingerlehre, p. 16. 
 
 3 Landw. Jahrb., 29 (1900), 961. 
 
MAGNESIA AS A FEETILIZEB 319 
 
 instances may be cited from experiments in Rhode Island, 1 
 and elsewhere in the United States. 
 
 It has long since been observed that experimenters 
 in different localities have sometimes secured quite op- 
 posite results from the use of magnesia, as, for example, 
 in the case of the good results secured by Ville when it 
 was used for wheat and the ill effect on wheat noted by 
 Passarini. 2 
 
 It has been pointed out by Storer that Tennant noted a 
 poisonous action of caustic magnesia, yet in recent ex- 
 periments at the Maryland experiment station caustic 
 magnesia at the rate of 1400 pounds per acre gave in 
 certain instances better results than the same amount of 
 calcium oxid in ground oyster shells. In fact, many 
 similar conflicting instances might be cited. 
 
 It has been stated that Von Raumer, in 1883, pointed 
 out the necessity of a proper relationship of lime to mag- 
 nesia in connection with plant growth ; and Knop called 
 attention at an early date to the fact that in water-culture 
 experiments certain calcium, potassium, or ammonium 
 salts were capable of counteracting the ill effects of an 
 excess of magnesia, and he suggested the applicability of 
 lime as an antidote for magnesia in field culture. Many 
 other investigators have found lime an antidote for an 
 excess of magnesia in field practice. Later, a theory was 
 advanced by Loew 3 which may explain, in many cases, 
 this interesting and important fact. 
 
 477. Loew's theory concerning magnesia. — In brief, 
 Loew holds "that a calcium protein compound partici- 
 
 i An. Rpt. R. I. Agr. Expt. Sta., 17 (1903-1904), 230-234. 
 
 2 Bol. Scuolo Agr., 3 (1895), 140-142 ; Abs. Jour. Chem. Soc. (London), 
 72, No. 142, II, 587. 
 
 3 Die landw. Vers.-Sta., 41, 466-475 ; also Flora (1892), 368-394 ; Bui. 
 18, U. S. Dept. of Agr., Div. of Veg. Phys. and Path. (1889), 42. 
 
320 
 
 FERTILIZERS 
 
 o 
 
 s .5 
 
 * 2 
 
 H S 
 
 ft T3 
 
 o £ 
 
 & a ^ 
 
 a m 
 
 O to 
 
 s h 
 
 . .3 
 
 - eg cs 
 
 •2 'a 
 
 2 « 
 
 
 pates in the organized 
 parts of the nucleus 
 and chlorophyl 
 body," and that 
 when magnesium 
 salts of the stronger 
 acids are made avail- 
 able to the plant, 
 the lime as the 
 stronger base would 
 " combine with the 
 acid of the mag- 
 nesium salt, while the 
 magnesia would enter 
 into the place which 
 the lime had occu- 
 pied in the organized 
 structure ; the ca- 
 pacity for imbibition 
 would thereby be 
 altered and a disturb- 
 ance of its structure 
 would result which 
 would prove fatal. 
 
 " On the other 
 hand, judging [from 
 the laws of the action 
 of masses, it would 
 naturally be inferred 
 that an excess of lime 
 salts would remedy 
 the evil effects by 
 making the reverse 
 
MAGNESIA AS A FERTILIZER 321 
 
 process possible." It is not to be assumed, however, 
 that all cases of injury arising from the use of magnesia 
 are due to the reason given by Loew and his various co- 
 workers, for other factors often come into play. It ap- 
 pears probable, nevertheless, that there are certain fairly 
 definite relations between lime and magnesia which are 
 best for given kinds of plants, and yet for other plants 
 they may be widely different. The recent work by Gile 
 shows that in some cases the importance of the very 
 close and definite relationship may have been overesti- 
 mated. The investigation of this question is, however, 
 yet in its infancy. 
 
 There has unquestionably been too great a tendency to. 
 explain cases of injury arising from the use of magnesium 
 salts on the basis of Loew's theory, for in many cases some 
 other explanation harmonizes far better with the observed 
 facts. 1 These attempts to support the theory of Loew 
 by frequent unwarranted claims have resulted in awaken- 
 ing unnecessary fear of magnesia poisoning, even in 
 regions where magnesia is not present in soils in undue 
 proportions as compared with lime, and where its applica- 
 tion is often followed by good results. 
 
 478. The ratios of lime and magnesia in different soils. 
 — It has been asserted by D. Meyer 2 that soils with an 
 especially high content of magnesia, as compared with the 
 lime, are quite exceptional ; yet Loew 3 cites analyses of 
 twenty soils from different parts of Japan in which the 
 magnesia exceeds the lime by from two to five times, and 
 the relations of the two in the soils of Japan have been 
 found to range from traces of lime associated with 0.475 
 
 1 An. Rpt. R. I. Agr. Expt. Sta., 17 (1903-1904), 221-260. 
 
 2 Landw. Jahrb. (1904), Heft 3. 
 
 3 Ibid. (1905), 133. 
 
 Y 
 
322 
 
 FERTILIZERS 
 
 per cent of magnesia to such limits as 1.618 per cent of 
 lime and 6.307 per cent of magnesia. Other analyses of 
 Japanese soils are also cited in which quite the opposite 
 relation was found to exist. 
 
 Magnesia has also been found in excess of the lime in 
 certain of the soils of Ohio, which have been greatly helped 
 by liming, yet the benefit in this case may well be 
 due chiefly to other effects than the correction of an un- 
 favorable ratio between lime and magnesia. Indeed, 
 
 Fig. 53. — Clover, Redtop, and Timothy, prominent in the Order 
 
 Named. 
 Hydrated magnesian lime with high magnesia content. "Complete" 
 fertilizer. Seeded to timothy, redtop, and clover, the same as in Figs. 
 52, 54, and 55. 
 
 even Loew {ibid., p. 135) calls attention to the neutralizing 
 value of both calcium carbonate and magnesium carbon- 
 ate, and to their frequent beneficial action, in this capac- 
 ity, upon the bacterial flora of the soil, which effects, he 
 admits, may in certain cases be so great as to obscure the 
 physiological effects due to correction of the calcium- 
 magnesium ratio. He also adds that otherwise in soils 
 containing about equal quantities of lime and magnesia 
 the yield of cereals would be depressed by an application 
 of either. 
 
 In order to arrive at the lime and magnesia available 
 
MAGNESIA AS A FERTILIZER 323 
 
 in the soil, Loew prefers an extraction of the fine earth 
 with 10 per cent hydrochloric acid rather than with a 10 
 per cent solution of ammonium chlorid, which was em- 
 ployed by Meyer. 
 
 479. Variations in magnesia content of different parts 
 of the same plant. — Instances are cited by Loew 1 of 
 certain seeds in which there are found one hundred mole- 
 cules of magnesia to seventeen of lime, and yet in the 
 leaves there were two hundred and twenty-four molecules 
 of lime to one hundred of magnesia. 
 
 480. Concerning the alleged toxic action of magnesium 
 chlorid. — It was suggested by Knop that in certain 
 soils sulfate of potash should be employed rather than 
 muriate of potash on account of the possibility that 
 magnesium chlorid might otherwise be formed, which 
 Knop regarded apparently as a positive plant poison. 
 
 According to the theory of Loew, magnesium chlorid 
 would be expected to have a toxic action upon plants, at 
 least whenever the lime was deficient. In fact, he states 2 
 that " calcium and magnesium chlorid have an injurious 
 effect upon plants, probably on account of the liberation 
 of hydrochloric acid in cells, this not being assimilated 
 like nitric and sulfuric acid and therefore accumulating 
 to a noxious degree." 
 
 It has been stated by L. von Wagner 3 that calcium and 
 magnesium chlorids are not good for potatoes and beets. 
 
 It is obvious that excessive a'hiounts of magnesium 
 chlorid, like other salts, must inevitably be injurious 
 to plant life ; the degree of injury depending upon the 
 kind of plant and the concentration of the salt solution. 
 
 1 Die landw. Vers.-Sta., 4-1 (1892), 473. 
 
 2 Bui. 18, U. S. Dept. of Agr., Div. of Plant Phys. and Path., 18. 
 
 3 Pfianzen-Produktions-Lehre (1874), 336. 
 
324 FERTILIZERS 
 
 A study of the effect of magnesium chlorid was made 
 by Wheeler and Hartwell 1 on a silt loam containing about 
 0.57 and 0.21 per cent, respectively, of lime and magnesia 
 soluble in strong hydrochloric acid, as determined by the 
 Hilgard method of soil analysis. The land had been 
 planted to Indian corn for several years, without fertilizer 
 or manures, until it would no longer produce a crop over 
 6 inches high in the course of a whole season. The 
 experiments were made in galvanized iron pots 18 inches 
 in diameter and 26 inches deep, with the bottoms sloping 
 to an opening in the center. The pots were set in soil 
 nearly to their tops over drain tile, which insured normal 
 conditions of temperature and prevented the backing up 
 of water into them from the surrounding soil. The first 
 two years all of the pots received acid phosphate, nitrate 
 of soda, and muriate of potash, and the third year dried 
 blood, basic slag meal, and potassium-magnesium car- 
 bonate (a product of the German potash works). The 
 average yield of barley plants per pot the first year, with- 
 out further treatment, was 43.7 grams, and upon the addi- 
 tion of 19.2 grams of hydrous magnesium chlorid per pot 
 the yield was 46.5 grams. By the use of 110 grams of 
 calcium carbonate per pot in addition to the magnesium 
 chlorid the average yield was raised to 67.9 grams; but 
 when caustic magnesia was added at the rate of 44 grams 
 per pot in place of the calcium carbonate, the average 
 yield fell to 6.1 grams. 
 
 The following year the application of magnesium chlorid 
 was repeated, and spring rye was grown. The average 
 yield with magnesium chlorid was 51.3 grams; the yield 
 where calcium carbonate had also been applied, the pre- 
 vious year, was 55.8 grams ; and where caustic magnesia 
 
 1 An. Rpt., R. I. Agr. Expt. Sta., 15 (1901-1902), 295-304. 
 
MAGNESIA AS A FERTILIZER 325 
 
 replaced the calcium carbonate, the yield was now 49.7 
 grams. The toxic action of the caustic magnesia, ob- 
 served the first year, had now practically vanished. It 
 was found that the addition of magnesium carbonate 
 at the rate of 59.2 grams per pot, where the caustic 
 magnesia had been applied the year before, resulted in 
 a depression of the yield to 41.4 grams. This second 
 year the check pots to which no magnesia had been 
 added in any form gave an average yield of but 3.7 
 grams. 
 
 The third year the crop was oats, and the average yield 
 with magnesium chlorid was 84.4 grams of oat plants per 
 pot. Where calcium carbonate had been added two years 
 before, the average yield was now 79.4 grams ; that 
 where caustic magnesia was used two years before was 
 87.9 grams ; and the yield where caustic magnesia was 
 used two years before, and magnesium carbonate a year 
 before, was 82.5 grams. It is of special interest to note 
 that the yield of the check pots as a result of using a basic 
 magnesian fertilizer was now 88.7 grams. The magne- 
 sium chlorid had not in this case proved materially or 
 positively toxic, since the differences are within the 
 reasonable limit of error. In view of the improvement 
 in yield from the use of calcium carbonate and the injury 
 from caustic magnesia the first year, it might have been 
 assumed, on the basis of Loew's theory, that the lime had 
 been helpful by virtue of counteracting an undue propor- 
 tion of magnesia ; yet such a conclusion is impossible in 
 view of the excellent results in every case in the last year, 
 where magnesium salts were used as additions to the 
 magnesium chlorid and the regular fertilizer. It has 
 since been shown by field experiments that this soil had 
 finally become so acid as to inhibit almost absolutely the 
 
326 FERTILIZERS 
 
 growth of timothy, clover, and barley, until the condition 
 was corrected by the addition of calcium carbonate, potas- 
 sium-magnesium carbonate, burned dolomite or slaked 
 lime (slightly magnesian). This fact accounts for the 
 poor results of the second year in the check pots when 
 muriate of potash and acid phosphate were used, and 
 also for the toxic action of ammonium chlorid when used 
 in an experiment under the same conditions as magnesium 
 chlorid. This also explains the effect, the first two years, 
 of calcium carbonate in more than counteracting the tox- 
 
 Fig. 54. — Redtop. (Clover and Timothy lacking.) 
 
 Complete fertilizer. No lime. Seeded to timothy, redtop, and clover, 
 
 the same as in Figs. 52, 53, and 55. 
 
 icity of the ammonium chlorid, and also the effect of the 
 basic fertilizer made up of basic slag meal, dried blood, and 
 potassium-magnesium carbonate, in correcting, in all 
 cases, the conditions in the check pots in the third year. 
 
 The foregoing results show that magnesium chlorid 
 is less toxic on certain soils than ammonium chlorid; 
 and still other experiments with the same soil indicate 
 that it is far less toxic than calcium chlorid. 
 
 481. Danger from using caustic magnesia and burned 
 and hydrated magnesian lime. — The preceding results 
 show that caustic magnesia was toxic at first when it 
 was used in large quantities, even on a soil evidently in 
 
MAGNESIA AS A FERTILIZER 327 
 
 slight need of magnesia, but that when sufficient oppor- 
 tunity had been afforded for it to become carbonated, it 
 became useful. It is probably on this account that special 
 care must be taken in employing a hydrated, air-slaked, 
 or burned magnesian lime immediately before planting 
 a crop, unless great care is taken to limit the quantity 
 used to moderate applications, and to most thoroughly 
 incorporate it with the soil. Such danger is obviously 
 greater on light, sandy, and gravelly soils, lacking in 
 moisture and vegetable matter, and less on heavier soils 
 rich in vegetable matter, especially if they are of an acidic 
 character. 
 
 482. The solubility of magnesium carbonate in its 
 relation to practice and experiment. — According to 
 Comey, 1 magnesium carbonate is more soluble than cal- 
 cium carbonate in water, carbonated water, and in am- 
 monium chlorid. It has also been shown by Tread well 
 and Reuter that one liter of water will hold only 0.385 gram 
 of calcium bicarbonate in solution, but that the same 
 amount of water will hold in solution at one time, not 
 only 1.954 grams of magnesium bicarbonate, but also 
 0.715 gram of magnesium carbonate. For this reason 
 there is much more danger of injury from heavy applica- 
 tions of burned and slaked magnesian lime than from the 
 pure lime, especially on soils but little in need of basic 
 applications, and for plants which are particularly suscep- 
 tible to such injury as may arise in consequence of the 
 creation of an alkaline reaction in the soil solution. Not- 
 withstanding that these figures may apply to magnesium 
 carbonate, which is formed by the taking up of carbonic 
 acid by slaked magnesian lime, it is doubtless not true of 
 the magnesium carbonate in natural magnesite, dolomite, 
 
 1 A Dictionary of Chemical Solubilities, London and New York, 1896. 
 
328 FERTILIZERS 
 
 or highly magnesian limestone ; for Hilgard x has pointed 
 out that magnesia in its native combinations leaches less 
 rapidly from soils, than lime, indicating that the relative 
 solubilities of artificial carbonates may be quite the re- 
 verse of the natural compounds. In fact, the mineral 
 magnesite (magnesium carbonate) is said to be probably 
 insoluble in water and not to be affected by boiling with 
 water or with aqueous solutions of alkaline carbonates. 2 
 Experiments conducted under the direction of B. L. Hart- 
 well, at the request of the writer, have also shown that 
 ground magnesian limestone, sufficiently fine to pass a 
 sieve with 50 meshes to the linear inch, was much less 
 soluble in carbonated water maintained in a state of 
 saturation than ground limestone passing a sieve of the 
 same mesh. In fact, the solubility of the latter was ap- 
 proximately three times as great as the solubility of the 
 former. 
 
 If, therefore, quick action is necessary, magnesium car- 
 bonate, if formed recently from burned magnesian lime, 
 would be expected to correct undue acidity of soils rather 
 more quickly than calcium carbonate ; but natural mag- 
 nesite, dolomite, or magnesian limestone might accom- 
 plish it less quickly than natural carbonate of lime. 
 
 It has been shown by H. Ley 3 that neutral salts check or 
 prevent dissociation, hence magnesium carbonate as well 
 as calcium carbonate may be expected to act favorably 
 on acid soils in preventing dissociations of compounds 
 possessing ions of a character injurious to plant growth. 
 On the other hand, the high solubility of magnesium 
 
 1 Soils, etc. (1906), 383. 
 
 2 Davis, Jour. Soc. Chem. Ind., 25 (1906), 788; cited from Cameron 
 and Bell, Bui. 49, Bur. of Soils, U. S. Dept. of Agr., 59. 
 
 3 Ber. d. deut. chem. Gesell., 30, 2192. 
 
MAGNESIA AS A FERTILIZER 329 
 
 carbonate, such as would be likely to be formed quickly 
 from burned magnesian limestone in the soil water, and 
 the possibility of creating by its presence alkaline condi- 
 tions unfavorable to certain plants, has been very fre- 
 quently neglected or ignored in farm practice and also in 
 experimental work. In consequence, in certain instances 
 very erroneous conclusions have doubtless been drawn. 
 In fact, no experimenter can afford to neglect the possibility 
 of such effects any more than he should, for example, the 
 possible influence of such compounds upon the ionization of 
 other salts, upon the bacterial life, or upon the physical 
 character of the soil. 
 
 483. Ranges in lime and magnesia content of plants 
 without material differences in yield. — It was found by 
 Wheeler and Hartwell in pot experiments with spring rye 
 in which the average yields of rye plants per pot were 
 50.5 and 51.3 grams, respectively, that in the former case, 
 in which calcium carbonate was employed, the ratio of 
 lime to magnesia was 6.3 to 1 ; whereas in the second 
 instance, where magnesium chlorid had been applied, the 
 ratio of lime to magnesia was 1.5 to 1. Results with 
 mangels were also secured in connection with which, in 
 addition to the regular fertilizer, caustic magnesia, sodium 
 carbonate, and air-slaked lime were employed. When 
 caustic magnesia was added to the usual fertilizer, the 
 yield was 126.3 grams of air-dried mangel " roots," and 
 the ratio of lime to magnesia was 6.4 to 1 ; when sodium 
 carbonate was added, the yield was 131.3 grams, and the 
 ratio of lime to magnesia was 1.6 to 1 ; when slaked lime 
 was used instead of the caustic magnesia or sodium car- 
 bonate, the yields in two cases were 148.2 and 132 grams 
 and the ratios of lime and magnesia 4.4 to 1 and 3 to 1, 
 respectively. Without further addition than that of the 
 
330 FERTILIZEBS 
 
 regular fertilizer^the yield was 91.3 grams and the ratio of 
 lime to magnesia was 4.2 to 1. 
 
 Attention has been called elsewhere to the fact that 
 plants may be physiologically relieved of certain excesses 
 of lime by its crystallizing out within them as insoluble 
 calcium oxalate and in some cases exteriorly as calcium 
 carbonate. The former disposition is impossible in the 
 case of magnesia, because of the solubility of the mag- 
 nesium oxalate. It must be evident, therefore, that in 
 
 Fig. 55. — Extreme Left, Redtop and Weeds. (No Clovek nor 
 
 Timothy.) 
 
 No lime. No fertilizer. Seeded to timothy, redtop, and clover, the 
 
 same as in Figs. 52, 53, and 54. 
 
 any discussion of the ratios of lime and magnesia in plants, 
 the possibility of such storing away of some of the lime in 
 insoluble, and hence in inactive form, must be taken into 
 consideration; yet in the instance here considered, it 
 does not seem probable that this factor could have had 
 much influence on the relation of the two. It appears, 
 therefore, as concerns the ratios of lime and magnesia within 
 the plant, that there may be in some cases very wide varia- 
 tions without an accompanying difference in yield. 
 
 484. Desirable lime and magnesia ratios in soils and 
 culture solutions. — According to Loew, 1 a relation of 2 of 
 
 1 Circular No. 10 (1909), Porto Rico Agr. Expt. Sta. 
 
MAGNESIA AS A FERTILIZER 331 
 
 lime to 1 of magnesia in soils is to be desired, because it 
 stands between that which is best for cereals, on the one 
 hand, and for the legumes on the other; he points out, 
 however, that the relative availability of the lime and 
 magnesia present in the soil may nevertheless change 
 these ratios materially, a difference not revealed by his 
 chemical method of determining them. Furthermore, 
 these generalizations, especially as to the legumes, may 
 be hasty and subject to material modification, depending 
 upon the individual legume concerned. 
 
 It has been established experimentally by Furuta and 
 Katayama x that the most advantageous ratio of lime to 
 magnesia is 1 to 1 for rice and oats, 2 to 1 for cabbage, 
 and 3 to 1 for buckwheat. It appears, in other words, in 
 accord with the relatively greater amount of lime in the 
 leaves, and of magnesia in the seeds, that plants with a 
 great leaf surface may require relatively more lime. 
 
 It was found by Bernadini and Corso that the best 
 ratio of lime and magnesia for maize was 2 to 1 ; for oats 
 in water-culture it was 1 to 1 ; and in soil culture 2 to 1 was 
 permissible ; but a depression in yield resulted with a ratio 
 of 3 to 1. It was noted by Takeuchi that a decrease of 
 two-thirds resulted in the growth of oats, when the ratio of 
 lime to magnesia was changed from 1 to 1, to 10 to 1. 
 
 The experiments of Aso, Bernadini, and Corso, and 
 likewise of Konowalow, have indicated the proper lime- 
 magnesia ratio for rice, wheat, rye, and barley to be 1 to 1. 
 For onions, Katayama found 2 of lime to 1 of magnesia 
 the best ratio. For leaf production, in the case of mul- 
 berry trees, Aso established the ratio of 3 of lime to 1 of 
 magnesia. 
 
 1 Bui. Col. of Agr., Tokyo, 4, Nos. 5 and 6. 
 
332 FERTILIZERS 
 
 For flax, Nakamura gives the proper ratio of lime to 
 magnesia as 1 to 1. 
 
 Experiments by Daikuhara 1 with a soil having 0.64 
 per cent of lime and 1.91 per cent of magnesia indicated 
 that a ratio of 3 of lime to 1 of magnesia is unfavorable 
 to beans, buckwheat, tobacco, and the cereals. 
 
 The recent work by Gile gives evidence of frequent wide 
 variations in the lime-magnesia ratios of soils, without 
 unfavorable effects on the plants. 
 
 485. Sources of magnesia. — Magnesia is available for 
 fertilizer purposes in several different forms : — 
 
 (1) Magnesite, magnesium carbonate (MgC0 3 ), occurs as 
 a native mineral in California, and elsewhere in the United 
 States, and it is found in considerable quantities in Eu- 
 rope. It is said to be insoluble in pure water and to be 
 exceedingly resistant to carbonic acid. 
 
 (2) Dolomite is a whitish-opaque calcium-magnesium 
 carbonate containing about 47.6 per cent of magnesium 
 carbonate, the remainder being carbonate of lime. 
 
 (3) Magnesian limestone is one in which a part of the 
 calcium carbonate is replaced by magnesium carbonate in 
 proportions ranging from traces of magnesium carbonate 
 to essentially the quantities present in dolomite. 
 
 (4) Dou le manure salt (double sulfate of potash and 
 magnesia) , also referred to as low-grade sulfate of potash, 
 and kainit. The latter contains magnesium sulfate, and 
 also carries considerable quantities of magnesium chlorid. 
 These salts and kieserit are considered more fully under 
 the chapter on potash salts. 
 
 1 Bui. Expt. Sta., Tokyo, 1, No. 1 (1905) ; cited from Loew. 
 
CHAPTER XXIII 
 
 SODIUM SALTS 
 
 Sodium is present in the air. as sodium chlorid, in the 
 shape of fine powder. This is derived chiefly from the 
 winds which sweep into the air the spray of the ocean and 
 of salt lakes. The winds also carry into the air salt dust 
 of terrestrial origin. The quantity of common salt thus 
 
 Full ration Full ration One-fourth ration Full ration 
 
 sodium carbonate potassium carbonate sodium carbonate, sodium carbonate. 
 
 One-fourth ration One-fourth ration 
 
 potassium carbonate potassium carbonate 
 
 Fig. 56. — Mangels, Limed. 
 
 Fertilized alike with phosphoric acid and nitrogen. 
 
 carried inland is sufficient to materially raise the chlorin 
 content of spring and well waters in near proximity to the 
 sea coast. 
 
 In addition to this atmospheric source of sodium, it is 
 a prominent constituent of many important and widely 
 distributed minerals and rocks. 
 
 486. Mineral sources of sodium salts. — Orthoclase, 
 one of the chief minerals of certain granites, frequently 
 contains from 2 to 6 per cent of soda ; oligoclase, also often 
 
 333 
 
334 FERTILIZERS 
 
 present in granite, contains 8 per cent of soda; diorite 
 likewise contains 3 per cent of soda ; and certain volcanic 
 rocks contain as much as 6 per cent. Thus these and other 
 sodium-bearing minerals and rocks add, by their disin- 
 tegration, to the soluble sodium salts of the soil, and hence 
 aid in their distribution throughout all arable soils. It 
 must be borne in mind, however, that in humid regions 
 sodium as chlorid, and also in other combinations, is being 
 continually leached way, whereas, on the contrary, in 
 arid regions the soluble sodium salts often accumulate to 
 such an extent as to inhibit plant growth, or at least the 
 growth of the usual agricultural plants. 
 
 487. Black alkali. — Chief among the noxious so- 
 dium salts is the so-called " black alkali " (sodium car- 
 bonate, Na 2 C0 3 ), which was so named because of the 
 dark color imparted to the otherwise white sodium car- 
 bonate, by vegetable decomposition products which it 
 dissolves. 
 
 488. Quantities of common salt injurious to crops. — 
 The soluble sodium of soils is present chiefly as chlorid, 
 although it may occur as nitrate, sulfate, carbonate, or 
 silicate. In dry soils quantities of sodium chlorid as great 
 as 1 to 1000 parts of soil are likely to be injurious to 
 plants, though in very wet soils nearly twice that quantity 
 may be endured. 
 
 489. The presence of soda in plants. — The presence of 
 soda seems to be practically universal in cultivated plants, 
 though the amounts in different plants vary widely accord- 
 ing to the nature of the plant and to the condition under 
 which it is grown. There is also a wide variation in the 
 percentages present in different parts of the same plant. 
 In elevated regions, very remote from the sea, the quan- 
 tity of soda present in plants is so small that cattle reared 
 
SODIUM SALTS 
 
 335 
 
 there require much more common salt than those fed on 
 plants grown nearer the sea. 
 
 According to Pagnoul, 1 Peligot first pointed out the 
 difference in the action of soda and of potash upon plants. 
 He made analyses of many varieties of plants, 2 and claimed 
 that the ash of most plants, including spinach, contained 
 no soda, although he found it in fodder beets and in species 
 of Atriplex and Chenopodium. When, later, Bunge 3 
 called attention to the faulty method of analysis by which 
 much or all of the soda might have been lost, Peligot re- 
 
 Full ration 
 common salt 
 
 Full ration 
 muriate of potash 
 
 One-fourth ration 
 
 common salt. 
 One-fourth ration 
 muriate of potash 
 
 Full ration 
 
 common salt. 
 
 One-fourth ration 
 
 muriate of potash 
 
 Fig. 57. — Mangels, Limed. 
 Fertilized alike with phosphoric acid and nitrogen. 
 
 peated some of his earlier work, 4 taking special precautions 
 against the loss of soda, and again found soda absent 
 from certain plants. 
 
 It was found by Deherain 5 and Sjollema 6 that potato 
 tubers were free from soda, notwithstanding that sodium 
 
 1 Ann. Agron. (1899), 467. 
 
 2 Compt. rend. (Paris), 2 (1867), 729 ; and in later issues of the same 
 journal. 
 
 3 Annal. de Chemie et Pharm., 172, 16. 
 
 4 Compt. rend. (Paris), 76 (1873), 113 ; Abs. Centralb. f. Agr. Chem., 
 4 (1873), 222-226. 
 
 6 Ann. Agron., 9 (1883), 511. 
 « Jour. f. Landw. (1899), 309. 
 
336 FERTILIZERS 
 
 salts were present in the manures. It is reported by 
 Pagnoul l likewise that potatoes grown in soil which con- 
 tained soda were themselves free from it, and later he 
 asserted 2 that sodium may be absent if large amounts of 
 potash are used in the manures. He found, however, 
 that oats absorbed soda if there was a deficiency of potash 
 in the manures and fertilizers. 
 
 That the use of sodium salts in the manures may in- 
 crease the quantity of it in some plants is shown by Zoller, 
 who found in the stems of beans 5.1 per cent when soda 
 was so employed, but only 1.36 per cent when it was not. 
 Similar wide variations were found by Wheeler and Hart- 
 well 3 in various crops. 
 
 It is reported that Coutejean and Guitteau 4 determined 
 the potash and soda percentages in over six hundred 
 varieties of plants, and large numbers of similar deter- 
 minations are given by Wolff. 5 It appears that the soda 
 content of plants may therefore vary from mere traces 
 to high percentages. The amount found by Hilgard 6 in 
 the ash of greasewood (Sarcobattus vermiculatus) was 40 
 per cent. 
 
 490. Sodium salts as indirect manures. — It was found 
 by Birner and Lucanus 7 that the application of sodium 
 sulfate favored the passage of phosphoric acid into the 
 plant and that it lowered at the same time the percentage 
 of lime. Upon applying potassium chlorid, the ash and 
 
 1 Compt. rend. (Paris), 80 (1875), 1010; Abs. Jahresb. f. Agr. Chem., 
 18, 259. 
 
 2 Ann. Agron., 20 (1894), 467-479. 
 
 3 An. Rpt., R. I. Agr. Expt. Sta., 19 (1905-1906), 235-251. 
 
 4 Compt. rend. (Paris), 86 (1878), 1151-1153; Abs. Centralb. f. Agr. 
 Chem. (1879), 259. 
 
 6 Aschen-Analysen. 
 
 6 Jahresb. f. Agr. Chem. (1892), 183. 
 
 'Landw. Vers.-Sta., 8 (1866), 140. 
 
SODIUM SALTS 337 
 
 dry matter of the plants were enriched in magnesia and 
 potash, but became poorer in lime, sulfuric acid, and phos- 
 phoric acid; and upon applying sodium chlorid a still 
 more striking change in the same direction ensued. On 
 the other hand, Storer x cites Dyer as authority for the 
 statement that common salt seems to be needed to bring 
 out the action of phosphates and nitrates, yet from ob- 
 servations by various experimenters it would appear that 
 there are many conditions under which common salt is 
 
 Full ration Full ration One-fourth ration Full ration 
 
 sodium carbonate potassium carbonate sodium carbonate, sodium carbonate . 
 
 One-fourth ration One-fourth ration 
 
 potassium carbonate potassium carbonate 
 
 Fig. 58. — Flat Turnips, Limed. 
 
 Fertilized alike with phosphoric acid and nitrogen. 
 
 used to check the too rapid formation or assimilation of 
 nitrates. It is apparent, therefore, that the effect produced 
 hinges upon the peculiar conditions which exist in any 
 given case. 
 
 It has been shown by various experimenters that upon 
 applying calcium salts to ordinary soils, considerable 
 amounts of potash are often rendered soluble, and the 
 high efficiency of sodium chlorid in this respect, under 
 exaggerated conditions, has been shown by Passarini. 2 
 Nevertheless, Muntz and Girard hold that if sodium chlorid 
 
 1 Agriculture, II (1897), 595. 
 
 2 Quorta Seine 17, Dist. la~2a; 72, della Raccolta Generate, 15. 
 
 z 
 
338 FERTILIZERS 
 
 exerts a solvent action upon soil phosphates or upon soil 
 silicates, containing potash, it must be extremely limited. 
 It must, however, be evident that rich potash-bearing 
 zeolites or, possibly, glauconite would be likely to yield 
 more potash than would be freed from feldspars ; and they 
 would also yield considerably greater quantities of potash, 
 if rich in that ingredient, than if they were poor in potash 
 at the outset and were already rich in soda, lime, and 
 magnesia. 
 
 In the course of experiments with sodium chlorid and 
 with sodium carbonate, at the experiment station of 
 the Rhode Island State College, the serious deficiency of 
 potash which soon developed, in a silt loam soil of granitic 
 origin, indicated, if there had been a liberation of potash 
 from zeolitic or other silicate combinations, that it could 
 neither have been of very great consequence at the outset 
 nor of long duration. In this case generous amounts of 
 readily available phosphoric acid, as well as occasional 
 applications in less available form, were made throughout 
 the course of the experiments, hence it was not a question 
 of liberation of native phosphorus compounds of the 
 soil. Under the circumstances which existed, it was 
 found that on both lightly and moderately limed soil, both 
 sodium compounds showed an unmistakable tendency, in 
 two or three different years and with several different crops, 
 to increase the percentage of phosphorus in the dry matter 
 of the plants. 1 
 
 491. Concerning the benefit to crops from applying 
 sodium salts. — The old and modern writers on agricul- 
 tural chemistry and on general agriculture agree that 
 marked benefit to farm crops often follows the application 
 of sodium salts, though reference is commonly made to 
 
 'An. Rpt., R. I. Agr. Expt. Sta., 19 (1905-1906), 194-219. 
 
SODIUM SALTS 
 
 339 
 
 sodium chlorid. Recently Smets and Schreiber x have 
 pointed out that sodium salts are highly beneficial to 
 certain plants under given conditions of field culture. 
 Frequent ill effects from such use of sodium chlorid are 
 nevertheless on record. 
 
 It is apparent that sodium salts act more beneficially 
 with some classes of plants than with others. From this 
 it must be inferred that the different plants require unlike 
 amounts of potash, which soda can liberate, that they are 
 
 Full ration 
 muriate of potash 
 
 One-fourth ration 
 
 common salt. 
 
 One-fourth ration 
 
 muriate of potash 
 
 Full ration 
 
 common salt. 
 
 One-fourth ration 
 
 muriate of potash 
 
 Fig. 59. — Flat Turnips, Limed. 
 Fertilized alike with phosphoric acid and nitrogen. 
 
 unequally affected by such biological and physical changes 
 in the soil as the use of soda may cause, or one is led to 
 conclude that soda probably performs functions of direct 
 physiological importance. 
 
 The general recognition in Great Britain of the benefit 
 from the application of common salt to soils is evident from 
 the statement by Griffiths 2 to the effect that 250,000 tons 
 of finely crushed common salt are used annually for ma- 
 nurial purposes in the United Kingdom. 
 
 In soils which contain calcium carbonate, it is possible 
 
 1 Recherches sur les Engrais Potassiques et Sodiques, Maaseyck 
 (1896). 
 
 2 A Treatise on Manures (1889), 256. 
 
340 FERTILIZERS 
 
 that common salt, by its reaction with sodium chlorid, 
 may give rise to sodium bicarbonate, which, being more 
 basic than the carbonate of lime, may affect the chemical 
 reaction of the soil either favorably or unfavorably ac- 
 cording to the variety of plant involved. It has even been 
 asserted that it may, by its solvent action, render certain 
 humous bodies of the soil either directly assimilable by 
 plants, or else aid in the more rapid change of some of 
 their constituents into other available forms of plant food 
 ingredients. It was found by Prianischnikov, 1 when 
 using sodium nitrate as a source of nitrogen in the growth 
 of plants, that the medium in which they grew became 
 alkaline by virtue of the sodium carbonate which resulted 
 after the removal and utilization of the nitric acid by the 
 plants. Indeed, this is in full accord with later observation 
 of others and with the earlier classification of sodium nitrate, 
 by Adolf Mayer, as a physiologically alkaline fertilizer. 
 
 492. The effect of sodium salts dependent on various 
 conditions. — That an excess of sodium carbonate in soils 
 may be injurious, is well attested by the evil effect of the 
 " black alkali " (sodium carbonate) of the arid and semi- 
 arid regions of Canada, the western part of the United 
 States, and elsewhere. If sodium chlorid is used on an 
 acid soil, practically devoid of carbonates of lime and mag- 
 nesia, it may aggravate the existing condition by ulti- 
 mately increasing the acidity, whereas on a soil where the 
 sodium chlorid can react with carbonate of lime to form 
 sodium bicarbonate, the reverse effect might follow. 
 
 493. The influence of sodium salts on the conservation 
 and movement of soil moisture. — It has been shown by 
 Ricome 2 in experiments with Malcolinia maritima and 
 
 1 Chem. Ztg., 66 (1900), 701. 
 
 2 Compt. rend., 137 (Paris, 1903), 141 ; Abs. Centralb. f. Agr. Chem., 
 33 (1904), 224. 
 
SODIUM SALTS 
 
 341 
 
 Alyssum maratinum that the presence of sodium chlorid 
 in the solution outside of the plant may lessen the quantity 
 of water absorbed, and thus protect it from an injurious 
 degree of transpiration. The presence of the sodium salt 
 in the plant itself was without beneficial effect in this 
 connection, unless the existing conditions were also such 
 as to permit of easier absorption. 
 
 Since soluble salts, such as sodium chlorid, increase the 
 surface tension of liquids, it has been pointed out by King 
 that they may be helpful by facilitating the movement of 
 
 Full ration 
 common salt 
 
 Full ration 
 muriate of potash 
 
 One-fourth ration 
 
 common salt. 
 One-fourth ration 
 muriate of potash 
 
 Full ration 
 
 common salt. 
 
 One-fourth ration 
 
 muriate of potash 
 
 Fig. 60. — Chicory, Limed. 
 Fertilized alike with phosphoric acid and nitrogen. 
 
 the soil water towards the surface, and hence towards 
 the plant roots. 
 
 In certain soils sodium chlorid exerts a beneficial floc- 
 culating influence, yet in others in which the bicarbonate 
 is readily formed, it may have the opposite effect. 
 
 It is generally held by farmers that common salt added 
 to a soil helps it to retain moisture, on which account it is 
 helpful on light sandy soils which are readily subject to 
 drought. This view is supported by the fact l that the 
 presence of salts in the soil solution lessens evaporation 
 from the surface so long as they remain in solution, and 
 
 1 King, A Textbook of the Physics of Agriculture (1901), 106. 
 
342 FERTILIZERS 
 
 in case they are separated at the surface, they then even 
 serve the purpose of a mulch. 
 
 494. The effect of sodium salts upon osmotic pressure. 
 — There appears to be evidence that conditions may arise 
 in which sodium salts, or other soluble salts, may be of 
 service in connection with the growth of plants in solu- 
 tions, merely by their increase of the osmotic pressure, 
 though whether this would have any bearing upon the 
 growth of plants in a normal way in soils is problematical. 
 
 495. The possible physiological and manurial functions 
 of sodium salts. — Some writers attribute to potassium 
 but the one function of aiding in the formation and trans- 
 location of starch, though Benecke 1 indicates others, for 
 in discussing sodium he suggests its osmotic service to the 
 plant as a substitute for potassium. As concerns potas- 
 sium salts, in this connection, Copeland 2 has asserted that 
 they are direct or indirect factors in maintaining turgor, 
 also that upon the omission of salts containing phosphorus, 
 magnesium, or sulfur, the plants, though showing poor 
 growth, exhibited high turgor, whereas in the absence of 
 potassium salts, the turgor was decreased and the growth 
 stunted. Nevertheless, Pfeffer 3 holds that turgor is a 
 result of conditions of growth rather than a cause of it; 
 a view which seems to have the greater support. 
 
 It is held by Pfeffer that phosphorus may be as essential 
 as potassium in effecting the formation and translocation 
 of starch ; and as sodium often aids in carrying phosphorus 
 to the plant, it may thus render an indirect service. 
 
 It has indeed been suggested by Goodale 4 that sodium 
 
 x Ber. deut. bot. Gesell., 12 (1894), Gen. Vers., 114; quoted from 
 Copeland. 
 
 2 Bot. Gazette, 24 (1897), 411. 
 
 » The Physiology of Plants (translated by Ewart) (1900), 1, 141, 
 
 4 Physiological Botany (1885), 255. 
 
SODIUM SALTS 
 
 343 
 
 may be substituted for a portion of the potassium required 
 by the plant. 
 
 Owing to the large quantities of sodium in certain plants, 
 A. Mayer thinks that it may perhaps be essential or at 
 least serviceable to them. 
 
 Fig. 61. — Onions. 
 With full ration of common salt. Fertilized liber- 
 ally with nitrogen and phosphoric acid and limed. 
 In these respects like Figs. 62 and 63. 
 
 Attention has also been called by Mayer to the free 
 movement of the salts of sodium within the plant, and he 
 suggests that soda may just as well combine with organic 
 acids in the plant as to have this service performed by 
 some other base, and yet this would be without necessary 
 
344 FERTILIZERS 
 
 physiological significance. In this connection an experi- 
 ment by Mercadante is of interest, for upon growing 
 species of Oxalis and Rumex, without potassium, neither 
 fruit nor flower formed, and but one-eighth the normal 
 amount of acid was present. The oxalic and tartaric 
 acids produced were found combined with lime, and but 
 little starch or sugar was formed. 
 
 Under normal conditions, therefore, some of the organic 
 acids, formed during the synthesis of the proteins, are 
 found combined with potassium. This suggests that not 
 only potassium, but also sodium, if there is a partial lack 
 of the former, may perform a highly useful function as a 
 neutralizer of organic acids, and, as Mayer has suggested, 
 it may act as a soluble conveyor of at least oxalic acid 
 to other parts of the plant, where by contact with lime the 
 acid is precipitated as insoluble calcium oxalate. As a re- 
 sult the acid is prevented from reaching toxic propor- 
 tions in certain vital parts of the plant. 
 
 It was held by Salm-Horstmar 1 as early as 1856 that 
 sodium was essential to wheat and oats, in connection with 
 the perfection of the seed. 
 
 From water-culture experiments with Indian corn, 
 Stohmann 2 concluded that sodium was essential to its 
 perfect development. It has been suggested by Miintz 
 and Girard that if sodium is essential, the mangel wurzel 
 is a plant most likely to require it. Sodium is mentioned 
 also by Aikman, Johnson, and others, as possibly essential 
 to plants ; but if so only in very minute quantities. 
 
 496. Results by Jordan and Genter. — It was con- 
 cluded by Jordan and Genter 3 that " soda cannot re- 
 
 1 Versuche und Resultate iiber die Nahrung d. Pflanze, 12, 27, 29, 
 and 36. 
 
 2 Flora (1890), 207-261. 
 
 8 Bui. 192, N. Y. (Geneva) Agr. Expt. Sta., December, 1900. 
 
SODIUM SALTS 345 
 
 place potash as an active agent in the development of 
 plant life," or, in other words, that it could not replace it 
 in function though taking the place of some of it in the 
 quantity found within the plant. 
 
 497. Soda in connection with diastatic action. — An 
 interesting suggestion as to a possible independent phys- 
 iological function of soda in plants has been made by 
 Suzuki * in which he recalls the work of Chittenden, show- 
 ing that the efficiency of vegetable diastase is heightened 
 by small quantities of sodium chlorid (0.24 per cent). 
 The same has been shown by Wachsmann 2 to be the case 
 with animal diastase; furthermore it has been observed 
 by A. Mayer that a 1 per cent solution of potassium chlorid 
 not only retarded diastatic action, but that smaller amounts 
 exerted no decisive effect. In consequence he concludes 
 that sodium chlorid may act indirectly, in conjunction 
 with the diastase, in the transportation of starch to the 
 growing tips of plants. 
 
 498. Atterberg's experiments with soda. — An experi- 
 ment is on record by Atterberg 3 in which plants were 
 grown in quartz sand in which, in one series, calcium salts, 
 and in another, sodium salts, were substituted for a part 
 of the potassium, with the result that the yields fell off in 
 the former case far more than in the latter. It has, how- 
 ever, been learned by correspondence that it was ascer- 
 tained later that the particular lot of sand which was used 
 in the experiments contained surprisingly large quantities 
 of sodium chlorid, and hence it may also have contained 
 some potassium salts capable of being liberated by sodium 
 salts in a greater degree than by the action of lime. This, 
 
 1 Bui. Col. of Agr., Tokyo, Imp. Univ., 6 (1905), No. 4, 408. 
 2 Pfiuger's Archiv, 91 (1902), 191. 
 3 Deut. landw. Presse (1891), 1035. 
 
346 
 
 FERTILIZERS 
 
 therefore, throws some doubt upon whether the benefit 
 was a direct one or was wholly or in part indirect, by virtue 
 of the liberation of potash. The following year Wagner 
 and Dorsch x called attention to the manurial value of 
 sodium salts, asserting that, in case potash was lacking, 
 sodium was capable, in connection with certain plants, of 
 
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 Fig. 62. — Onions with Muriate or Potash. 
 
 Full ration of muriate of potash. Fertilized lib- 
 erally with nitrogen and phosphoric acid s and limed. 
 In these respects like Figs. 61 and 63. 
 
 increasing the crop as much as one-half. Still later Stahl- 
 Schroeder published certain researches which seemed to 
 him to contradict the idea that the sodium in the experi- 
 ments by Atterberg and by Wagner and Dorsch had ex- 
 erted a direct effect, but rather that it was indirect by 
 virtue of the liberation of potassium. 
 
 499. The experiments at Bernburg. — In a series of 
 
 1 Die Stickstoffdiingung d. landw. Pflanzen (1892), 227-242. 
 
SODIUM SALTS 347 
 
 experiments by Hellriegel, Wilfarth, and others, 1 at Bern- 
 burg, Germany, made in quartz sand or in mixtures of 
 sand and peat, extracted previously in order to remove 
 practically all of the available potassium, it was found 
 that there was an increase in crops of barley and oats, 
 when a deficiency of potash in the manures was partially 
 made up by additions of sodium salts. There were in- 
 dications, nevertheless, that buckwheat, potatoes, and 
 perhaps other crops may not be benefited by sodium 
 compounds. 
 
 In discussing the work of Hellriegel and Wilfarth, 
 Schneidewind 2 calls attention to the fact that they were 
 able, by substituting some soda for a part of the potash in 
 the fertilizers, to produce the same amounts of sugar and 
 of total dry matter as with the use of more potash. The 
 latter believed, nevertheless, that the good effect of soda, 
 which he had also observed in connection with beets, 
 was not due to physiological functions of the sodium 
 salts, but to the fact that the solubility of the sodium 
 nitrate, sodium phosphate, and sodium sulfate was 
 greater than the solubility of the corresponding potassium 
 salts; and that on this account the several plant foods 
 when in combination with sodium were more available. 
 This latter conclusion is, however, open to serious 
 question in view of the fact that Hellriegel and Wilfarth 
 worked in pots which were watered artificially in order that 
 optimum amounts of water might at all times be main- 
 tained in the soil; furthermore, under ordinary soil con- 
 ditions plants are known to make use, in a satisfactory 
 manner, of the various potassium salts. 
 
 It has been pointed out by Hartwell and Pember 3 
 
 1 Arbeiten Deut. landw. Gesell., Hefts 34 and 38. 
 
 2 Jour. f. Landw. (1898), 7, 8. 
 
 3 An. Rpt., R. I. Agr. Expt. Sta., 21, 249, 250. 
 
348 FERTILIZERS 
 
 that in the experiments by Hellriegel and Wilfarth, when 
 sodium was added, more potassium was removed in the 
 crop than otherwise ; and, furthermore, that the increase 
 in growth was no more than might have been expected 
 from the extra potassium thus rendered available. It 
 was assumed by the latter investigators that when the 
 sodium salts were deficient in the soil-culture medium, some 
 of the potash applied in the fertilizers was fixed by the 
 silica or otherwise, in such form that all of it could not 
 be readily secured by the plants, but that a part of the 
 potassium thus fixed was rendered available to a greater 
 degree upon the addition of sodium salts. 
 
 500. The Rhode Island experiments. — It was on 
 account of the many conflicting ideas as to the possible 
 functional benefit of sodium salts that the matter has been 
 studied exhaustively at the experiment station of the 
 Rhode Island State College. At first, plants were grown 
 in the field, in which case great benefit from common salt 
 and from sodium carbonate resulted, when employed in 
 connection with small applications respectively of muriate 
 of potash and of potassium carbonate. In fact, even 
 in cases where more than 300 pounds of muriate of potash, 
 or its equivalent of potassium carbonate, were employed, 
 the yields of mangel wurzels were doubled by sodium salts. 
 In all cases heavy applications of organic nitrogen (chiefly 
 in dried blood) and of available phosphates were made, 
 in order to eliminate, in so far as possible, any effect of 
 the sodium salts by way of rendering nitrogen and phos- 
 phoric acid available to the plants. In the course of this 
 work many different kinds of plants were analyzed in 
 order to determine the influence of the soda upon the 
 composition of the mineral matter : and, in some cases, 
 1 An. Rpt., R. I. Agr. Expt. Sta., 19, 186-316. 
 
SODIUM SALTS 
 
 349 
 
 upon the organic constituents of the plants. This work 
 indicated that benefit from soda seemed to have resulted, 
 in certain cases, which could not be readily explained 
 upon the assumption that it was due to a greater liberation 
 of potash. In order, however, to further remove doubt 
 
 r'~*?£. •_ v3s3 
 
 8E* -v 1 
 
 < 'S&JjP 
 
 k. " -7 .JlKt ^mmrri 
 
 ■%>*,■ ■"• \, *--* 
 
 
 - 
 
 ir?i^3wr^fti^ '-£ 'M^' -■'■„•?' '•' ■' 
 Mf&vTtr-' — -."■■< ...-■ — 
 
 
 ^i;^rp 
 
 
 ^ f"^ iiifc~nr-r 
 
 Fig. 63. — Onions. 
 FmZZ ration of common salt and full ration of mu- 
 riate of potash. Fertilized liberally with nitrogen 
 and phosphoric acid, and limed. In these respects 
 like Figs. 61 and 62. 
 
 on this point, an extensive series of water-culture experi- 
 ments was made at the Rhode Island station by Wheeler, 
 Hartwell, and Pember, 1 and by Braezeale, under condi- 
 tions where indirect manurial action was impossible. 
 Precautions were also taken to eliminate the possibility 
 of benefit from the sodium salts being due to a change in 
 
 i An. Rpt., R. I. Agr. Expt. Sta., 20 (1906-1907), 299-357 ; An. Rpt., 
 21 (1907-1908), 243-285. 
 
350 FERTILIZERS 
 
 the relation of the nutrients, to the chemical reaction, to 
 the concentration of the solution, or to other similar 
 effects, rather than to some physiological function of the 
 sodium salt. As a result it appeared that though possibly- 
 unable to wholly replace potash in any one function, or 
 at least in all of its functions, in connection with the 
 growth of certain plants, sodium may and often does 
 perform some part of one or more of the important func- 
 tions of potassium, and thus increase the amount of dry 
 matter which the plant can produce. 
 
 501. The practical significance of soda in agriculture. — 
 The most practical feature connected with the utilization 
 of sodium salts is to use for the growing of mangels, 
 radishes, turnips, and such other crops as can make good 
 use of them, fertilizers like nitrate of soda and kainit, 
 which furnish nitrogen and potash ; and at the same time, 
 without added cost, supply soda. The soda, in such cases, 
 serves as an insurance against a possible shortage of 
 potash and may materially add to the yields. 
 
CHAPTER XXIV 
 
 IRON AND MANGANESE 
 
 The importance of iron to plants has long been known, 
 and now new interest attaches to manganese. 
 
 502. Iron in its relation to plant growth. — Experi- 
 ments have shown that a lack of iron in plants causes 
 pathological chlorosis, and it is believed that it may- 
 affect the protoplasmic structure in which the chlorophyl 
 is deposited. It is therefore vital to the higher plants. 
 
 The necessity of iron may be readily shown by growing 
 Indian corn or other plants for some time in a nutritive 
 solution, which is complete excepting for the omission of 
 iron. After having reached an advanced stage of chlorosis, 
 the condition can still be remedied in a very short time by 
 the addition of ferric chlorid to the nutrient solution. 
 
 Sufficient iron is present in practically all soils to meet 
 the ordinary needs of plants. It has, nevertheless, been 
 asserted that certain soils of northern Michigan are so 
 deficient in this element that the plants grown upon them 
 do not furnish sufficient iron to the cattle of the region to 
 permit of their being brought successfully to maturity. 
 It is stated that this can be accomplished, nevertheless, 
 if they are supplied with fodder brought from elsewhere, 
 or if they are removed after a time to some other section 
 of the state. 
 
 Certain salts of iron may be reduced to lower oxid com- 
 binations under anaerobic soil conditions, or the lower 
 
 351 
 
352 FERTILIZERS 
 
 combinations may be oxidized upon draining the land or 
 in times of drought. This latter change accounts for the 
 frequent transformation from a bluish to a reddish brown 
 tint observed in soils when, upon their exposure to the air, 
 iron carbonate is oxidized to hydrous sesquioxid of iron. 
 Where, as in muck and peat soils, the conditions are at 
 times only partially favorable to oxidation, toxic organic 
 compounds of the lower oxid of iron are said to result. 
 In better aerated bogs, also, toxic iron protosulfate (FeS0 4 
 + Aq.) may be formed by the oxidation of iron sulfid 
 (FeS 2 ), provided the latter is present in the sands or 
 gravels frequently used as a covering for the surface. 
 In the latter case the toxicity can be counteracted by lim- 
 ing, whereupon the iron salt is broken up to form gypsum, 
 and the iron is further oxidized. Similar, but usually less 
 striking, effects may also be noted in wet uplands. 
 
 503. Manganese in plants and soils. — It has been 
 said that the existence of manganese in plants was first 
 pointed out by Scheele, who found it in the ash of wild 
 anise and of certain kinds of woods. It was later noted by 
 Herapoth in the ash of the radish, beet, and carrot and by 
 Salm-Horstmar in oats. 
 
 In 1872 Le Clerc recognized manganese as almost 
 universally present in soils and plants, although present 
 in the former usually in quantities much below 1 per cent. 
 
 504. Manganese as a fertilizer. — It was found by 
 Giglioli that manganese dioxid increased the yields of both 
 corn and wheat. 
 
 Experiments by Fukutome l have shown that the em- 
 ployment of ferrous sulfate, in conjunction with manganese 
 chlorid, was very helpful to flax, whereas either employed 
 without the other had but little effect. In experiments by 
 
 1 Bui. Col. of Agr., Tokyo, 6 (1904-1905), 137. 
 
IRON AND MANGANESE 353 
 
 Garola, also with flax, it was found that the employment 
 of salts of manganese in the manures not only increased 
 the growth, but also the assimilation of nitrates, phos- 
 phorus, potassium, calcium, and other ingredients. 
 
 Soils that were " oat-sick " were restored by Sjollema 
 and Hudig to a normal condition upon the employment of 
 manganese sulfate. 
 
 The amounts of manganese which may be safely and 
 often profitably applied per acre, range, according to 
 various experimenters, from nine to thirty-six pounds per 
 acre. It is recommended that the salts be pulverized and 
 mixed with the chemical fertilizers which are employed, 
 or that they be mixed with the stable manure before it is 
 applied to the land. 
 
 505. The manganese in Hawaiian soils. — Recent 
 examinations of certain black Hawaiian soils have shown 
 that they contain from about 4 per cent to nearly 10 per 
 cent of manganese oxid (Mn 3 4 ), whereas the red soils of 
 Hawaii show a range of from only 0.15 to 0.37 per cent. 
 
 506. Plants unlike in endurance of manganese. — It 
 appears that agricultural plants are very unlike in their 
 relation to manganese, for the quantity present in the 
 black Hawaiian soils, although not enough to interfere 
 with the successful growth of sugar cane, is so toxic to 
 pineapples that the plants often fail to bear fruit. Like- 
 wise Aso l found rice more resistant than either barley or 
 wheat to salts of manganese, and he has also shown that 
 its ill effects are worse in cold than in warm weather. 
 
 507. Variations in the manganese content of plants. — 
 Manganese is very commonly present in the ash of plants, 
 and Kelley 2 reports that the content of Mn 3 4 found 
 
 1 Bui. Col. of Agr., Tokyo, Imp. Univ., 5, 177-185. 
 
 2 The Jour, of Ind. and Eng. Chem., 1 (1909), 536. 
 2a 
 
354 FERTILIZERS 
 
 in the ash of pineapple leaves varied from 1.65 to 2.12 
 per cent, which he considers low in view of the high man- 
 ganese content of the soil upon which they were grown. 
 In the ash of the bark and leaves of the Norway spruce, 
 Schroeder found 35.5 and 41.2 per cent, respectively, of 
 Mn 3 4 . The fact that so little manganese is found 
 in some plants has led to the suggestion that possibly at 
 certain stages of the growth of the plant it may pass back 
 into the soil through the roots, or that it may be excreted 
 from the aerial portions of the plants, as has been shown 
 to be the case with certain other mineral plant constituents. 
 
 508. The effect of manganese on enzymes. — It was 
 shown by Bertrand l many years ago that much manganese 
 is present in the ash of oxidizing enzymes and that certain 
 soluble salts of manganese increase the power to carry 
 oxygen. In consequence, he suggested its practical trial 
 by making application of it to the soil. 
 
 The beneficial results from the use of manganese are 
 supported also by the experiments of Loew and Sawa. 
 The latter investigators found that manganese sulfate, 
 in moderate quantities, was toxic to barley. It exerted 
 a bleaching action upon the chlorophyl, and increased 
 the intensity of the oxidase and peroxidase reactions. 
 
 509. Manganese increases many crops. — When used 
 in very dilute solutions, manganese sulfate was found by 
 Loew and Sawa to promote the development of the plants. 2 
 The same was found by Aso to be true of rice ; and Na- 
 gaoka 3 reports an increase of 37 per cent in rice, upon the 
 application of 13.7 pounds of manganese sulfate per acre 
 (77 kilos per hectare). A similar result is reported by 
 
 i Compt. rend. (Paris), 124, 1032. 
 
 2 Bui. Col. Agr., Tokyo, Imp. Univ., 5, 172. 
 
 3 Ibid., 6, No. 1. 
 
IBON AND MANGANESE 355 
 
 Voelcker from Woburn (England) in experiments with 
 wheat and other crops. In experiments by Sutherst 1 
 it was found that small amounts of manganese compounds, 
 including the dioxid, were helpful to maize, yet he states 
 that Salamone found large amounts injurious. 
 
 It has been shown by A. Anduard and P. Anduard that 
 the employment of manganese increased the yields of 
 wheat and of kidney beans, but lessened slightly the yields 
 of carrots and of potatoes. 
 
 510. Roots change the oxidation of manganese. — In 
 view of the alleged oxidizing power of plant roots, which 
 it is asserted is even stimulated by salts of manganese, it 
 is of interest to note that Kelley found the soil darker 
 immediately about the roots of unhealthy pineapple 
 plants than elsewhere, and that Aso discovered man- 
 ganese dioxid adhering to the roots of wheat grown in 
 solutions containing manganese sulfate, thus showing that 
 the roots effect a change in the oxidation of the manga- 
 nese. It is, however, claimed by Schreiner and Sullivan 2 
 that the beneficial effect of manganese is due to its pro- 
 moting oxidation; they assert, however, that "the re- 
 lation between oxidation and catalysis is not as clear as 
 it should be, even in the plant where it has been exten- 
 sively studied." It is evident in any event that manga- 
 nese, if employed for its alleged " catalytic," "stimulating," 
 or " oxidizing " effect, must be used very cautiously, es- 
 pecially if the degree of sensitiveness of the particular 
 plant under experiment is not known at the outset. 
 
 511. Manganese may aid chlorophyl development. — 
 In growing plants by way of water-culture, it has been 
 found that if iron is slightly deficient, the addition of a 
 
 1 The Transvaal Agr. Jour., 6, No. 23. 
 
 2 Bureau of Soils, Bui. 73, U. S. Dept. of Agr. (1910). 
 
356 FERTILIZERS 
 
 soluble manganese salt causes chlorophyl development 
 and the renewed vigor that would be expected in such a 
 case ; yet, as was pointed out by Sachs l and later by 
 Loew and Sawa, iron cannot be fully replaced by manga- 
 nese in the production of chlorophyl. 
 
 A very full review of the experiments thus far conducted 
 with manganese is given by Giglioli and Rousset, 2 and 
 brief reference to much of the work is also made by 
 Schreiner and Sullivan (I. c.) and others. 
 
 1 Hoffmeister, Handbuch Phys. Botanik, 4 (1865), 144; cited from 
 Schreiner and Sullivan. 
 
 2 Ann. Sci. Agron., 2 (1909), 81. 
 
CHAPTER XXV 
 
 CHLORIN, SULFUR, SILICA, CARBON DISULFID, TOLUENE, 
 AND OTHER MISCELLANEOUS SUBSTANCES 
 
 Many miscellaneous substances including iodin, bromin, 
 boron, lithium, and others have been tested as to their 
 influence on plant growth, but only the more important 
 of these are considered in this chapter. 
 
 512. Chlorin. — Whereas there have been some in- 
 stances in which chlorin has seemed to be slightly bene- 
 ficial to plant growth, especially in connection with buck- 
 wheat, potatoes, and possibly other plants, through some 
 indirect action not definitely determined, it is nevertheless 
 considered as a non-essential element. For this reason 
 it is not classed as a plant food. 
 
 513. Sulfur. — Sulfur is essential to plant growth, and it 
 is required in considerable amounts in the formation of 
 certain essential oils, like those of the horseradish, cress, 
 and for the proteins, which are present in all plants. It 
 is, nevertheless, one of the elements supposed to be sel- 
 dom, if ever, so deficient in soils as to require that it be 
 supplied artificially. This is more especially the case in 
 regions where the extended use of ready-mixed commercial 
 fertilizers is common, since they usually contain consider- 
 able quantities of gypsum as one of the ingredients, not 
 only of ordinary superphosphates, but also of certain of 
 the German potash salts. Sulfur is also added to soils 
 in potassium sulfate, in the low and high grade sulfates of 
 
 357 
 
358 FERTILIZERS 
 
 potash, and likewise in the protein compounds of nitroge- 
 nous organic fertilizing materials. 
 
 514. Sulfur may become depleted in soils. — It has 
 been shown by Hart and Peterson that where farm-yard 
 manure is applied to soils regularly and in reasonable quan- 
 tities, the original quantity of sulfur in the soil is maintained 
 or even increased. Soils, on the contrary, which have been 
 cropped for from fifty to sixty years, and which have re- 
 ceived but little manuring, were found to have lost 40 per 
 cent of their original sulfur, as indicated by comparisons 
 with similar virgin soils. 
 
 It has been further pointed out by Hart and Peterson 
 that many crops remove sulfur from the soil in much 
 greater quantities than those usually given in the tables 
 of analyses of farm crops. This fact, however, may merely 
 signify that a great excess of sulfur is present in the soil 
 in assimilable form, and hence the results may serve as a 
 more effective argument against its lack than for the ne- 
 cessity of its application. 
 
 515. The relation of sulfur and phosphorus in plants 
 and soils. — The fact has also been pointed out by Hart 
 and Peterson that the amount of sulfur trioxid represented 
 in average crops of the grain and straw of cereals is about 
 two-thirds as great as the amount of phosphoric acid which 
 these crops remove ; that in mixed meadow hay the quan- 
 tities of the two are about equal ; and in certain legumes the 
 amount of sulfur trioxid represented may approach, and 
 in alfalfa even exceed, the amount of the phosphoric acid. 
 
 An average crop of cabbage is said to remove from the 
 soil the equivalent of 100 pounds per acre of sulfur trioxid, 
 and in normal soils the amount in an acre-foot of soil was 
 found by the method of fusion with sodium peroxid to be 
 only from 1000 to 3000 pounds. 
 
CHL0R1N AND OTHER SUBSTANCES 359 
 
 The annual addition to the soil of sulfur trioxid in the 
 rainfall, as estimated by Hart and Peterson, for Madison, 
 Wisconsin, is said to be from 15 to 20 pounds per acre, 
 whereas the estimated losses by leaching, based upon the 
 yearly drainage from the Rothamsted (England) experi- 
 mental fields, are assumed to be about 50 pounds per 
 annum. 
 
 516. Need of sulfur may need investigating. — In 
 view of the preceding, and other facts, and of the attention 
 called by Bogdanov, 1 as well as by Dymond, Hughes, and 
 Dupe 2 to the possible importance of the sulfur question, 
 Hart and Peterson believe that the possible need of an 
 artificial supply of sulfur should be given due considera- 
 tion in connection with future researches involving soils 
 and fertilizers. 
 
 517. Silica in plants. — Silica is an important con- 
 stituent of the ash of the grasses and rushes and also of 
 many other plants. The ashes of some clovers, and of 
 the straws of cereals, have been found to contain from 40 
 to 70 per cent of silica. In fact, this plant silica, by virtue 
 of its unusual solubility, may have some heretofore un- 
 considered value in the soil, in connection with green 
 manuring and with the use of stable manure and straw, 
 by way of aiding in the formation of zeolitic double salts 
 of lime, magnesia, and the alkalies, by which the absorp- 
 tive capacity of light soils may be advantageously in- 
 creased. 
 
 518. Suggested functions in plants. — Silica has been 
 supposed to serve as a protection and support in the cell 
 walls, although not considered absolutely essential to plant 
 growth. 
 
 1 Abs. E. S. R., 11, 723. 
 
 2 Jour. Agr. Sci., England, 1 (1905), 217. 
 
360 FERTILIZERS 
 
 It has been asserted by Wolff that silica favors the mi- 
 gration of phosphoric acid from maturing stems and leaves 
 to the seeds which are in process of development ; for he 
 secured a larger number of perfect grains in its presence 
 than in its absence. Nevertheless, four generations of 
 maize were grown by Jodin without silica, other than that 
 derived from the dust of the air and from the vessels used 
 in the experiment, but yet without apparent ill effect upon 
 the plants. From what is now being learned about in- 
 dividual plant peculiarities, it would, however, be unwise 
 to conclude from experiments with maize as to the needs 
 of all other higher plants. 
 
 519. Silica may replace other ingredients in the " lux- 
 ury " consumption. — In experiments with oat plants 
 Wolff determined, in the presence of an abundance of all 
 of the other essential elements, the minimum of each which 
 was necessary, but found nevertheless that he could not 
 grow plants containing only these minima of all of them. 
 In other words, there seems to be required a certain 
 excess of mineral matter beyond such calculated minima, 
 a part of which/' luxury " need may be supplied by silica 
 very much as sodium seems to answer a part of the general 
 need for a soluble base when potash is present only to the 
 extent of that minimum vital to plant growth. 
 
 520. Silica deposition checks sap diffusion. — It has 
 been suggested by Ritthausen that silica performs a useful 
 function through its well-regulated and gradual deposition 
 as a gelantinous mass in the walls of cells, by which the 
 diffusion of sap is gradually suspended, especially in the 
 lower leaves which gradually become unnecessary and 
 ineffective. By this process, the chief portion of the plant 
 food contained in such leaves, together with all of the sap, 
 is ultimately diverted to the building up of new shoots 
 
CHLORIN AND OTHER SUBSTANCES 361 
 
 and to parts of the plant which, in the later stages of growth, 
 have become more important. 
 
 521. Carbon disulfid often increases crops. — It was 
 pointed out by A. Girard in 1894, in connection with ex- 
 periments extending over a number of years, that highly 
 beneficial effects upon the growth of plants followed ap- 
 plications to the soil of carbon disulfid, which had been 
 used at the rate of 2904 pounds 1 per acre for the destruc- 
 tion of beet nematodes. The beet crop was ruined by the 
 treatment, but the following year the wheat crop on the 
 treated area was much better than elsewhere. Subse- 
 quent experiments, in which carbon disulfid was used 
 at the same rate, resulted in a gain of from 15 to 46 per 
 cent in the yield of wheat grain, and of from 21 to 80 per 
 cent in wheat straw. The yield of potatoes was similarly 
 increased by from 5 to 38 per cent, and that of beets from 
 18 to 29 per cent. The yield of clover was also increased 
 by from 67 to 119 per cent. In the case of oats there was 
 an increase in 1891 of 9 per cent in grain and of 30 per cent 
 in straw. At Joinville, in 1892, oats showed a gain, from 
 its use, of 100 per cent in grain and of 60 per cent in straw. 
 
 522. Reasons suggested for the benefit to soils from 
 using carbon disulfid. — For a long time much doubt 
 existed as to the cause of the benefit which resulted from 
 the use of the carbon disulfid. Among the suggestions 
 offered in explanation was one to the effect that the ma- 
 terial might have acted as a " stimulant," also that it 
 might have aided by destroying certain " injurious sub- 
 terranean insects " or " cryptogamic organisms," which 
 might otherwise exert an injurious effect upon the roots 
 of plants. This latter view was held by C. Oberlin, 2 an 
 
 i Also E. S. R., 6 (1894-1895), 564, 565. 
 2 Ibid., 565. 
 
362 FERTILIZERS 
 
 Alsatian viticulturist who had made similar observations 
 on vegetables, cereals, and forage crops. 
 
 It was suggested by Milton Whitney that the effect of 
 the carbon disulfid might be due to an alteration of the 
 physical character of the soil. 
 
 It had already been established by Warrington and was 
 supported later by J. Perraud x that carbon disulfid checks 
 excessive nitrification, but it was supposed that this was 
 offset by benefit in other directions. 
 
 Subsequent investigations made by P. Wagner led him 
 to conclude that the preservative action of carbon di- 
 sulfid on stable manure, and its beneficial action on soils, 
 were probably due to its destruction of denitrifying or- 
 ganisms. 2 
 
 523. Treatment of soils with carbon disulfid costly. — 
 The expense of the disulfid treatment at the time of the 
 earlier experiments was very great. In fact, at the French 
 price, 3^ cents per pound, it cost $96 per acre, and at the 
 prevailing American prices, due to the high tariff and other 
 causes, the cost of treatment was $290 per acre. The 
 use of such costly' amounts of carbon disulfid simply for 
 soil improvement was obviously not economical, but the 
 experiments justified the belief that if but 175 to 290 
 pounds per acre were employed, or such quantities as were 
 customarily applied in vineyards, that some benefit would 
 result aside from the mere destruction of the phylloxera. 
 
 524. Carbon disulfid cures certain vetch clover and 
 alfalfa " sick " soils. — Certain experiments by Oberlin 3 
 have shown great benefit from the previous employment 
 of carbon disulfid. He found that a soil made " alfalfa 
 
 i Abs. E. S. R., 6 (1894-1905), 565. 
 
 2 L'Engrais, 10 (1895), No. 18, 423; Abs. E. S. R., 7, 25. 
 
 3 Jour. Agr. Prat., 59 (1895), 459-464, 499-503, 535-540. 
 
CRLOEIN AND OTHER SUBSTANCES 363 
 
 sick "by the continuous growth of the crop for six years 
 could be effectually cured by it, at least for a time. Sim- 
 ilar results were secured also with hairy vetch and crimson 
 clover. It is of interest to note that, among other queries, 
 Oberlin raised the question if the treatment destroyed all 
 soil organisms or only certain classes of them. 
 
 525. Carbon disulfid not the only unusual compound 
 to benefit soils. — It is impossible here to follow all of 
 the developments in connection with sterilization by the 
 heating of soils, likewise the use of carbon disulfid and 
 all of the many other soil disinfectants, catalyzers, stimu- 
 lants, indirect fertilizers, or whatever they may have been 
 termed. Among these may be prominently mentioned 
 toluene, tricresol, chloroform, zinc sulfate, and potassium 
 permanganate. Most, or at least many of these com- 
 pounds are too costly to permit of their general extensive 
 application, even though they may be highly beneficial 
 in certain special cases, and zinc compounds and certain 
 other substances may, by their accumulation in the soil, 
 become ultimately toxic. 
 
 526. Disinfectants, like heating, destroy soil amebe. 
 — Recently added interest has been lent to the subject of 
 disinfecting soils by the observations of Loew l to the effect 
 that soil " infusoria, flagellatae, and amcebe devour great 
 numbers of microbes." This was soon- followed by the 
 address of A. D. Hall 2 delivered at Sheffield, England, in 
 1910, in which he called attention to the fact that Russell 
 and Hutchinson of the Rothamsted laboratory had found 
 that soils which had been subjected to sterilization by 
 chemical treatment were found to contain exceptional 
 amounts of ammonia, sufficient, in fact, to account for their 
 
 i Science, 31 (1910), 988. 
 *!&«*., 32 (1910), 363. 
 
364 FERTILIZERS 
 
 subsequent increased fertility. It was further pointed 
 out that the sterilization was not complete, yet at the out- 
 set it greatly lessened the number of bacteria. This was, 
 however, but temporary, for after the soil was watered and 
 allowed to stand, it was discovered that they had increased 
 far in excess of the normal numbers. A given Rothamsted 
 soil, for example, containing normally seven million bac- 
 teria per gram, contained but four hundred after heating ; 
 yet a few days later the number present amounted to six 
 millions and later reached forty millions per gram of 
 soil. 
 
 Toluene treatment. — Treatment of the soil with toluene 
 resulted similarly, and the increase in ammonia in the soil 
 was explained by the rapid multiplication of bacteria, a 
 conclusion suggested by the fact that their increase was 
 coincident with this gain. The nitrifying bacteria were 
 eliminated by the treatment, and those remaining were of 
 the ammonifying group. This work led to the idea that 
 the treatment had destroyed something which had pre- 
 viously limited the bacterial development, and upon fur- 
 ther investigation it was found to have been the protozoa 
 which fed upon the living bacteria. With the destruc- 
 tion of these protozoa the ammonification of the organic 
 matter in the soil progressed rapidly. The protozoa prob- 
 ably concerned in the destruction of the bacteria were 
 found to be amebe and ciliates, for they were killed by 
 partial sterilization. 1 
 
 527. Destruction of soil protozoa may explain benefit 
 from soil " firing '" and deep plowing. — The preceding 
 observations afford a probable explanation of a part of the 
 beneficial results following the old practice of " firing '-'■ 
 or burning soils ; and also the practice of the Bombay 
 
 1 Russell, E. J., Science, 36 (1913), 520. 
 
CHLOBIN AND OTHER SUBSTANCES 365 
 
 tribes, who were accustomed to burn rubbish with as much 
 of the surface soil as possible before sowing their seed ; for 
 such treatment would be highly destructive to protozoan 
 life. 
 
 It has since been claimed by Loew that the protozoa 
 can probably only exist on or near the surface layers of 
 such soils as are very compact, for the reason that the 
 bacteria would be likely to render the store of air at the 
 lower levels unfit for the respiration of the many proto- 
 zoa. Nevertheless, in the Rothamsted soil, amebe are 
 found at considerable depths. It may nevertheless be 
 true that they exist chiefly in the surface layers of other 
 soils. If this be true, the suggestion of Loew's might ex- 
 plain some part of the benefit sometimes resulting from 
 deep plowing, as compared with a shallow working of 
 the soil by harrowing, since the protozoa would be trans- 
 ferred thereby to the lower levels and would possibly be 
 largely destroyed, thus giving a better chance for the 
 development of the beneficial bacteria and for the rapid 
 accumulation of an abundance of quickly available nitro- 
 gen. 
 
 528. The general applicability of soil disinfection 
 doubted by Loew. — Notwithstanding that Loew admits 
 the possible correctness of the conclusion of the Rotham- 
 sted investigators, and the possibility of the usefulness of 
 such treatment in special cases, he does not think that it 
 will admit of general application ; furthermore, he points 
 out the chance for the increase of possibly harmful as well 
 as of beneficial organisms, as a result of sterilization. It 
 is asserted, however, by Russell 1 that, " The improvement 
 in the soil is permanent ; the high bacterial numbers being 
 kept up even for 200 days or more." 
 
 1 Science, 37 (1913), 519. 
 
366 FERTILIZERS 
 
 529. The chlorid of lime treatment of soil tried by Loew. 
 
 — In connection with the study of a soil which had become 
 sick for lilies, Loew made a trial of carbon disulfid, tri- 
 cresol, potassium permanganate, and chlorid of lime. It 
 was found that beneficial results followed the use of all of 
 these substances, but that chlorid of lime was the most 
 effective and the least costly of them all. Since this is 
 perhaps the first time that chlorid of lime (bleaching 
 powder) has ever been used for this particular purpose, it 
 may be stated that to an area 1.5 meters long and 1 meter 
 wide, 100 grams of chlorid of lime were applied, dissolved 
 in 5 liters of water. A part of the solution was spread 
 over the surface, and the remainder was poured into holes 
 made in the soil. 
 
INDEX 
 
 A. B. C. method of conserving hu- 
 man excrement, 17. 
 
 Abraumsalz, 7. 
 
 Acid phosphate, definition of, 201 ; 
 sometimes dyed black, 208. 
 
 Acid soils yield dark extracts with 
 ammonium hydroxid, 268. 
 
 Acids, fatty, in guano, 76. 
 
 Actinomycetes as decomposers of 
 humus, 39. 
 
 Aerobacter, 42. 
 
 Aerobic organisms active in dung, 
 42. 
 
 Ahlendorff & Co., 82. 
 
 Ahnfeldtia plicata, 66, 231. 
 
 Aikman, 344. 
 
 Albinus, 165. 
 
 Algae, marine, see sea-weeds. 
 
 Algerian phosphates, 181, 182 ; 
 composition of, 182 ; contain 
 little iron and alumina, 182 ; 
 good effect of, on "Hochmoor" 
 soils, 182. 
 
 Alkali, black, 334 ; is sodium car- 
 bonate colored with vegetable 
 matter, 334. 
 
 Alsa menhaden, 88. 
 
 Aluminum and iron silicates in 
 phosphates sometimes objection- 
 able, 221. 
 
 Aluminum phosphate, 185 ; action 
 of water on, 186, 188 ; artificial, 
 solubility of, 186 ; efficiency of, 
 increased by roasting, 185, 186 ; 
 solubility of, affected by acid and 
 alkaline solutions, 188 ; solubility 
 in citric acid, 186 ; solubility in- 
 creased by ammonium salts, 186 ; 
 solubility in oxalic acid, 186. 
 
 Alunite of little value as a fer- 
 tilizer, 243. 
 
 Amebe, destroyed by disinfectants, 
 destroy microbes, 363. 
 
 Amidase, use in treating distillery- 
 waste, 112. 
 
 Amids in manure, 29. 
 
 Ammonia, absorbed by soil, 30 ; 
 absorbed by various substances, 
 31 ; fermentation in soils pro- 
 moted by destroying protozoa, 
 363 ; how held in soils, 30, 31 ; in 
 manure, 29 ; preserved by gyp- 
 sum, 32 ; said to be expelled from 
 soils by lime, 283, 284 ; synthetic, 
 production of, 146 ; volatiliza- 
 tion of, 20. 
 
 Ammonification, method of Lipman 
 for determining nitrogen avail- 
 ability by, 124. 
 
 Ammonite, 94. 
 
 Ammonium chlorid, early use of, at 
 Rothamsted, 7 ; see chlorids. 
 
 Ammonium nitrate costs little for 
 transportation per unit of nitro- 
 gen, 146 ; rarely used for manu- 
 rial purposes, 146. 
 
 Ammonium salts, first employed as 
 manures, 7 ; synthetic production 
 of, 146. 
 
 Ammonium sulfate, absorption of, 
 by soils, 148, 149 ; aids in ren- 
 dering certain grasses dominant, 
 155, 156 ; availability of, deter- 
 mined by Wheeler and Hartwell, 
 119; appearance of, 147; com- 
 position of, 147, 148 ; conditions 
 produced by, in acid soils not 
 equally toxic to all plants, 153, 
 
 367 
 
368 
 
 INDEX 
 
 154, 155 ; develops acidic condi- 
 tions, 149 ; early use of, at Roth- 
 amsted, 7 ; effects double decom- 
 positions in the soil, 151 ; effect 
 of, on maturity of plants, 157 ; 
 efficiency of, as a fertilizer, 150 ; 
 exhausts soils of lime, 149, 158 ; 
 fleeting in effect, 158, 159 ; gives 
 better results than nitrates in 
 later stages of growth of some 
 
 _ plants, 160 ; importance of the 
 effect of, on the soil reaction, 151 ; 
 impurities in, 147, 148 ; influence 
 of soda in comparisons of, with 
 nitrate of soda, 151 ; leaches less 
 readily than nitrates, 159 ; liber- 
 ates plant food, 158 ; manufac- 
 ture of, 147 ; may cause injury 
 on light calcareous soils, 159, 160 ; 
 may cause partial sterility on ex- 
 ceedingly acid soils, 152 ; may 
 cause the suspension of certain 
 bacterial activity, 157, 158 ; 
 must not be mixed with certain 
 alkaline substances, 148 ; nitro- 
 gen of, fixed by microorganisms, 
 149, 150 ; on acid soils drives out 
 clover and certain grasses, 156 ; 
 reaction of, with calcium carbo- 
 nate, 149 ; reacts with zeolites, 
 149 ; results with, in Rhode 
 Island, 152 ; results with, in Wo- 
 burn, England, 152. 
 
 Amylobacter, 42. 
 
 Anaerobic bacteria in manure, 39. 
 
 Anaerobic organisms active in 
 dung, 42. 
 
 Anderson, 231. 
 
 Anduard, A., and Anduard, P., 
 355 
 
 Anhydrit, 236. 
 
 Antiseptics, as preservatives of 
 manure, 34 ; in manure disad- 
 vantageous, 37. 
 
 Apatite, action of carbonic acid on, 
 178 ; action of water on, 178 ; 
 another name for phosphorite, 
 175 ; composition of, 177, 178 ; 
 distribution of, in soils, 175 ; oc- 
 
 currence of, 177 ; utilization of, 
 by process of Palmaer, 178. 
 
 Aristotle, 250. 
 
 Artificial basic slag meal, 198. 
 
 Ascophyllum nodosum, 66, 69. 
 
 Ashes, see wood, lime-kiln, cotton 
 seed. 
 
 Aso, 331, 353, 355. 
 
 Aspergillus amidase, 47. 
 
 Atterberg, 140, 318, 345, 346. 
 
 Atwater, 5. 
 
 Aubury, 297. 
 
 Available phosphoric acid, see phos- 
 phoric acid. 
 
 Azotin, 94. 
 
 Azotobacter chroococcum, 134, 135. 
 
 Bacillus amylobacter, 43 ; arce, 47 ; 
 boocopricus, 44 ; erythrogenes, 45 ; 
 fermentationis cellulosm, 43 ; fluo- 
 rescens, 42 ; fluorescens liquefa- 
 ciens, 47 ; mesentericus ruber, 38, 
 42, 43 ; methanigenes, 43 ; pas- 
 teuri freudenreichii, 45 ; puncta- 
 tum, 42 ; suaveolens, 42 ; subtilis, 
 38 ; thermophilus grignoni, 38. 
 
 Backhaus and Cronheim, 36, 38. 
 
 Bacteria, aerobic, 38 ; aid ammoni- 
 acal fermentation, 38 ; anaerobic 
 in manure, 39 ; denitrifying, 
 action of, on cellulose, 43 ; de- 
 stroyed by protozoa, 40 ; increase 
 of, accompanies increased am- 
 monification after soil disinfec- 
 tion and heating, 364 ; in manure 
 decrease gradually, 37. 
 
 Bacterial activity, effect of sulfate 
 of ammonia on, 156, 157. 
 
 Baker Island guano, 77. 
 
 Barilla, 232. 
 
 Barley, best lime-magnesia ratio 
 for, 331 ; effect of manganese on, 
 354 ; manganese salts in moder- 
 ate amounts toxic to, 354. 
 
 Barn-yard manure, see manure. 
 
 Basic cinder, see basic slag meal. 
 
 Basic slag meal, artificial, 198 ; 
 care in mixing with ammonium 
 salts and with organic nitrog- 
 
INDEX 
 
 369 
 
 enous substances, 196, 198 ; con- 
 stitution of, 194, 195 ; contains 
 less free lime than earlier, 194 ; 
 discovery of process for making, 
 8 ; effect of fineness of, 193 ; im- 
 proves the physical condition of 
 certain soils, 195 ; on clayey 
 soils, 195 ; influence of silica on 
 availability of, 192 ; ingredients 
 of, 193 ; methods of determining 
 the availability of, 192, 193; 
 methods of determining free lime 
 in, 194 ; not to be confused with 
 blast furnace slag, 191 ; on acid 
 pasture lands brings in clover, 
 196 ; on acid uplands action ideal, 
 196 ; on peat and muck soils, 
 195 ; other names for, 191 ; over- 
 production of, in Europe, 8 ; prac- 
 tical use of, 195 ; probably not a 
 tetracalcium phosphate, as at 
 first supposed, 195 ; process of 
 manufacture of, 191 ; range in 
 composition of, 192 ; varies in 
 availability, 192. 
 
 Beans, best lime-magnesia ratio for, 
 332 ; kidney, effect of manganese 
 on, 355 ; unlike as to effect of lime 
 on, 308. 
 
 Beatson, 75. 
 
 Belgian phosphate, 180. 
 
 Bell, see Cameron. 
 
 Benecke, 342. 
 
 Bergen, 231. 
 
 Bergstrand, 231. 
 
 Berkeland and Eyde, 8, 126. 
 
 Bernadini and Corso, 331. 
 
 Bertrandj 354. 
 
 Beseler, 143. 
 
 Bessemer process for the manufac- 
 ture of steel, basic slag a by- 
 product of, 8. 
 
 Bird manure, see Mago and Cato. 
 
 Birner and Lucanus, 336. 
 
 Black alkali, see alkali. 
 
 Blood, crystallized, 97 ; dried, 
 process for preparing, 97, 98 ; 
 dried, availability of, 98, 99 ; 
 dried, hygroscopic, 98 ; dried, 
 
 2 B 
 
 nitrogen availability of, 122 ; 
 dried, red, chemical composition 
 of, 97 ; dried, red, nitrogen con- 
 tent of, 96 ; dried, red, sometimes 
 adulterated, 96, 97. 
 
 Bogdanov, 359. 
 
 Bolley, 297. 
 
 Bone, a favorite, with American 
 farmers, 169 ; ash of, 167 ; black, 
 dissolved or vitriolated, 169 ; 
 chemical composition of, 166, 167, 
 206 ; disintegration of, by fermen- 
 tation, 169 ; dissolved, 206 ; 
 early use of, as a manure, 165 ; 
 effect of steaming on nitrogen 
 content of, 168 ; effect of steam- 
 ing on, 206 ; effect of steaming on 
 phosphoric acid content of, 168 ; 
 gathered from battlefields, 166 ; 
 organic framework of, 167 ; other 
 elements in, 166,167; raw, 168; 
 raw more available than steamed 
 on some soils, 169 ; removal of 
 fat from, 167 ; replaced largely 
 at present by acid phosphate, 
 170 ; steamed, 168 ; treatment 
 of, with sulfuric acid, 202 ; waste 
 from industries, 168, 169 ; 
 weathered, composition of, 167. 
 
 Bone-black, dissolved, largely re- 
 placed by acid phosphate, 206; 
 treatment of with sulfuric acid, 
 206. 
 
 Bone meal, gradually improves 
 acid soils, 170 ; the reverted 
 phosphoric acid of, 170, 171 ; the 
 soluble phosphoric acid of, 170 ; 
 too slow to replace lime for the 
 correction of soil acidity, 170. 
 
 Bone tankage, see tankage. 
 
 Bonnet, 2. 
 
 Boussingault, 3, 6, 103, 282, 311. 
 
 Bradley, see Lovejoy. 
 
 Braezeale, 349. 
 
 Brandt, 165. 
 
 Bretfield, 317. 
 
 Brewer's grains, the composition 
 of, 111. 
 
 Bristles, the composition of, 103. 
 
370 
 
 INDEX 
 
 Brooks, 174, 241, 242. 
 
 Brown, 276. 
 
 Buch, 212. 
 
 Buckland, 178. 
 
 Buckwheat, the best lime-magnesia 
 
 ratio for, 331. 
 Bunge, 335. 
 Burchard, 46. 
 
 Cabbage, best lime-magnesia ratio 
 for, 331. 
 
 Calcium acetate, effect of, on potato 
 scab, 301. 
 
 Calcium carbide, 161 ; use in com- 
 bining nitrogen, 8. 
 
 Calcium carbonate, compared with 
 burned lime, 275, 276 ; compared 
 with burned lime in Pennsylvania, 
 275 ; depresses ammonification 
 of cotton-seed meal, 285 ; effect 
 of, on potato scab, 301 ; effect of, 
 on the solubility of iron phosphate 
 in soils, 190 ; prevents the red- 
 dening of blue litmus paper by 
 fine soil particles, 270 ; stimu- 
 lates the ammonification of dried 
 blood, 285 ; see also limestone, 
 ground. 
 
 Calcium chlorid, effect of, on potato 
 scab, 301 ; see chlorids. 
 
 Calcium cyanamid, a new product, 
 161 ; changes in, taking place in 
 the soil, 162 ; compares favorably 
 with ammonium sulfate as a fer- 
 tilizer, 163 ; decomposed by high 
 steam pressure, 161 ; dicyanamid 
 formed from, 163 ; first works for 
 the manufacture of, 162 ; gradu- 
 ally decomposes, yielding am- 
 monia, 162 ; has an ultimate 
 basic effect on soils, 163 ; how 
 produced, 8 ; may be used in the 
 manufacture of creatin, 163 ; may 
 be used in the manufacture of 
 urea, 163 ; output of, 164 ; 
 process for the manufacture of, 
 161 ; sold mixed with peat, 163 ; 
 toxic in its action, at the outset, 
 163. 
 
 Calcium-magnesium ratio, effect of, 
 on higher plants, 286 ; possible 
 effect of, on nitrification of organic 
 substances, 285. 
 
 Calcium nitrate, a new fertilizer, 
 125 ; a result of cheap electricity, 
 125 ; as a carrier of lime, 128 ; as 
 a fertilizer, 128 ; at first too 
 hygroscopic, 127 ; chemical com- 
 position of, 127, 128 ; conserves 
 * lime supply of soils, 128 ; injury 
 to workmen and horses, in apply- 
 ing earlier product, 128 ; price 
 based on that of nitrate of soda, 
 129 ; process for making less 
 hygroscopic, 127 ; process of 
 manufacture, 126, 127 ; tendency 
 in soils the opposite of ammonium 
 sulfate, 128. 
 
 Calcium oxalate, effect of on potato 
 scab, 301. 
 
 Calcium salts, like sodium chlorid, 
 liberate potash, 338. 
 
 Calcium sulfate aids the nitrification 
 of urine, 285. 
 
 Cameron, 210, 211, 251, 268; and 
 Bell, 190, 212, 314 ; and Hurst, 
 186, 189, 214; and Seidell, 211, 
 212. 
 
 Carbohydrates, destruction of, in 
 dung, 41. 
 
 Carbon disulfid, as a preservative 
 of manures, 34 ; believed to pre- 
 vent denitrification, 362 ; cures 
 soils which are vetch, clover, and 
 alfalfa, "sick," 362, 363; idea of 
 Whitney concerning, 362 ; not 
 the only unusual compound to 
 show benefit on soils, 363 ; often 
 increases crops, 361 ; shown to 
 check excessive nitrification, 362 ; 
 many theories regarding action 
 of, have been suggested, 361, 362 ; 
 treatment of soils with, costly, 
 362 ; view of Oberlin concerning, 
 361. 
 
 Carbonato of lime, see calcium 
 carbonate ; also limestone, 
 ground. 
 
INDEX 
 
 371 
 
 Carbonate of potash, 241, 242; on 
 acid soils superior to muriate, 
 242. 
 
 Carbonate of soda, see sodium car- 
 bonate. 
 
 Carnallit, 236, 237 ; composition of, 
 237. 
 
 Caro, see Frank. 
 
 Carrots, effect of manganese on, 355. 
 
 Castor pomace, composition of, 
 110; nitrogen^ availability of, 
 122. 
 
 Catalysis, as an aid in the synthetic 
 production of ammonia, 146; re- 
 lation between, and oxidation not 
 yet clear, 355. 
 
 Catalytic substances, 9. 
 
 Cato, 1. 
 
 Caustic magnesia, see magnesia, 
 caustic. 
 
 Cellulose, amount in manure, 41 ; 
 destroyed by aerobic bacteria, 
 43 ; destruction by anaerobic 
 organisms in manure, 43. 
 
 Cereal and other seed by-products, 
 109, 110. 
 
 Cereals, best lime-magnesia ratio 
 for, 331. 
 
 Chalk, early use of, 1. 
 
 Chamber or wet acid process, 100. 
 
 Chemicals and manures, factors 
 governing the use of, 62. 
 
 Chincha Island guano, 78, 83. 
 
 Chinese, use of manures by, 1. 
 
 Chittenden, 345. 
 
 Chlor-apatite, 177. 
 
 Chlorid of lime, 40 ; amounts of, to 
 apply, 366; cured lily "sick" 
 soils, 366 ; treatment of soils 
 with, by Loew, 366 ; mode of 
 applying, 366 ; more effective and 
 cheaper than carbon disulfid, tri- 
 cresol, or potassium permanga- 
 nate, 366. 
 
 Chlorids, claimed by Nobbe to help 
 buckwheat, 247 ; claimed by 
 Pfeiffer to help potatoes, 247 ; 
 found by Pagnoul bad for pota- 
 toes, 247 ; ill effects of, due to 
 
 lack of carbonates, 248 ; ill 
 effects of, in potassium salts, 246 ; 
 Loew's explanation of ill effects 
 of, 246 ; not good for certain 
 crops, 246 ; opposing views con- 
 cerning, 247 ; reasons for divers 
 opinions concerning, 247, 248, 
 249 ; use of, increases the need of 
 lime, 248 ; views of Griffiths as 
 to ill effects of, 247 ; views of 
 Nobbe concerning, discredited by 
 A. Mayer, 247. ' 
 
 Chlorin, a, non-essential element, 
 357 ; occasional slight benefit 
 claimed for, 357. 
 
 Chloroform, effect of, on soils, 363. 
 
 Chrondrus crispus, 66, 73, 231. 
 
 Cipley, phosphates from, 181. 
 
 Cladostephus verticillatus, 66, 231. 
 
 Cocoons, 108 ; composition of, 108. 
 
 Cod waste, 88. 
 
 Colombian guano, 80. 
 
 Comey, 327. 
 
 Common crab, composition of, 92. 
 
 Common salt, see salt. 
 
 Compounds, definite, definition of, 
 250. 
 
 Coniferous trees, absorbent power 
 of needles of, 27. 
 
 Cook, 242. 
 
 Copeland, 255, 342. 
 
 Coprolites, a term sometimes used 
 improperly, 179 ; appearance of, 
 179 ; composition of, 179 ; dis- 
 covery of, in England, 7 ; distri- 
 bution of, 179 ; origin of name of, 
 178 ; sometimes of so-called con- 
 cretionary origin, 179 ; where 
 found, 178. 
 
 Coquilles animalisees, 93 ; a mix- 
 ture of mollusks and star-fish, 93. 
 
 Corso, see Bernadini. 
 
 Cotton, action of, on blue litmus 
 paper, 268, 269. 
 
 Cotton-seed hull ashes, composi- 
 tion and use of, 229 ; once used 
 largely for tobacco, 228. 
 
 Cotton-seed meal, 110; composi- 
 tion of, 110; nitrogen, avail- 
 
372 
 
 INDEX 
 
 ability of, 122 ; used for cotton, 
 tobacco, and sugar cane, 110. 
 
 Cotton-waste, absorbent power of, 
 28. 
 
 Coutejean and Guitteau, 336. 
 
 Coville, 281. 
 
 Cow manure, see manure. 
 
 Crab, see common crab. 
 
 Crangon vulgaris, 91. 
 
 Cress, sulfur in, 357. 
 
 Cronheim, see Backhaus. 
 
 Crookes, 125. 
 
 Curry, see Morse. 
 
 Cushman, 243. 
 
 Daikuhara, 332. 
 
 Dassonville, 317. 
 
 Davy, 3. 
 
 Deherain, 40, 56, 58, 159, 216, 267, 
 280, 335 ; and Dupont, 48. 
 
 Denitrification, an anaerobic pro- 
 cess, 265 ; greater if much ma- 
 nure is used, 58, 59 ; various 
 factors affecting, 59, 60. 
 
 Den treatment of phosphates, 204. 
 
 De Ruyter de Wild, see Sjollema. 
 
 De Sassure, 3, 7. 
 
 Deutsche Landwirthschafts Gesell- 
 schaft, 57. 
 
 Devil's apron, 66, 67. 
 
 De Vries, 255. 
 
 Diastatic action in manure, 42 ; 
 caused by molds and actinomyce- 
 tes, 42, 43. 
 
 Dicalcium phosphate, made by 
 partial acidulation of bone, 202 ; 
 see also phosphate. 
 
 Dietzell, 47. 
 
 Dillisk, 66, 68. 
 
 Diorite, amount of soda in, 334. 
 
 Disinfectants, destroy soil amebe, 
 363. 
 
 Disinfection of soils not believed by 
 Loew to have general applica- 
 tion, 365 ; claimed by Russell to 
 have lasting effects, 365. 
 
 Dissolved bone, see bone. 
 
 Distillery waste wash, a source of 
 nitrogen, 111 ; Effront's process 
 
 of treating, 112; industrial utili- 
 zation of, 111 ; Vasseux's process 
 of treating, 111. 
 
 Dolomite, 263, 332 ; composition 
 of, 263. 
 
 Dorsch, see Wagner. 
 
 Double carbonate of potash and 
 magnesia, analysis of, 241 ; to be 
 avoided on highly magnesian 
 soils, 241; useful on acid soils, 
 241. 
 
 Double manure salt, see sulfate of 
 potash, low grade. 
 
 Double sulfate of potash and mag- 
 nesia, 240, 241, 332; costs more 
 than muriate, 240 ; has given 
 good results with apple trees, 241 ; 
 magnesia content of, 240, 241 ; 
 to be avoided on highly mag- 
 nesian soils, 240. 
 
 Dried blood, availability of, deter- 
 mined by Wheeler and Hartwell, 
 119 ; see also blood. 
 
 Dry spot, see oats. 
 
 Duhring, 41. 
 
 Dulse, 66, 68. 
 
 Dung, changes in non-nitrogenous 
 matter of, 41 ; collecting and car- 
 ing for, 20 ; early Use of, 1 ; 
 effect of feed and age of animal 
 on, 19 ; terms used in discussing, 
 48, 49, 50 ; see also manure. 
 
 Dupe, 359. 
 
 Dupont, 38 ; see also Deherain. 
 
 Dusart and Pelouze, 212. 
 
 Dyer, 222, 251, 337. 
 
 Dymond, 359. 
 
 Eber, W., 49. 
 
 Eckenbrecher, 115. 
 
 Eel-grass, 69, 231. 
 
 Emmerling, 143. 
 
 Enzymes, oxidizing, manganese in, 
 
 354. 
 Eremacausis, 49. 
 Erlwein, 129. 
 Excrement, Bible reference to, 11 ; 
 
 solid, amount per day, 12, 13. 
 Excrement, human, 10 ; A. B. C. 
 
INDEX 
 
 373 
 
 method of conservation of, 17 ; 
 care in using, 18 ; conservation 
 of by Orientals, 14 ; conservation 
 of, in Paris, 14, 15 ; disposal of, in 
 Europe, 13, 14, 15 ; number of 
 microorganisms in, 35 ; Sinder- 
 mann's method of disposal of, 17 ; 
 treatment with burned lime, 16, 
 17. 
 Eyde, see Berkeland. 
 
 Farm manures, see manures. 
 
 Fats, decomposition of, in manure, 
 44; destruction of, in dung, 41. 
 
 Feathers, 103 ; composition of, 103. 
 
 Feces, see excrement. 
 
 Feldspar, of little value as a direct 
 fertilizer, 243 ; shown by Hart- 
 well and Pember to have no prac- 
 tical value, 243, 245 ; value 
 claimed for it by Cushman, 243. 
 
 Felt refuse, 107 ; composition of, 
 107 ; use as a manure, 107. 
 
 Ferments, use of, in treating dis- 
 tillery waste, 112. 
 
 Ferric phosphate, 188 ; solubility of 
 artificial, in various substances, 
 188, 189. 
 
 Feuille, 75. 
 
 Finger-and-toe disease, 299. 
 
 Fish, as a source of phosphoric acid, 
 172; composition of, 172 ; needs 
 supplementing, 91 ; nitrogen 
 availability in, 122 ; scrap may 
 be used without treatment, 91. 
 
 Fish guano, see guano, fish. 
 
 Fish scrap, acts quickly in warm, 
 moist climates, 91 ; acts slowly 
 in cold climates, 91 ; best on 
 light soils, 91 ; value depends 
 upon the climate and soil, 91. 
 
 Fish waste, in Norway, 88 ; water 
 in, 89. 
 
 Flagellatse devour microbes, 363. 
 
 Flax, best lime-magnesia ratio for, 
 332. 
 
 Floats, action of manure on, 173 ; 
 effect of liming on availability of, 
 174, 175; how to use, 174; 
 
 nature of, 173 ; soils the most 
 useful on, 173. 
 
 Florida phosphates, 183. 
 
 Fluor-apatite, 177. 
 
 Fluorids as preservatives of ma- 
 nures, 34. 
 
 Forchhammer, 231. 
 
 Fourcroy and Vauquelin, 45. 
 
 Frank and Caro, 8, 161. 
 
 Frankland, 131, 159. 
 
 Fraps, 186. 
 
 French phosphates, 180. 
 
 Frezier, 75. 
 
 Fucus, see Ascophyllum . 
 
 Fukutome, 352. 
 
 Furuta, 331. 
 
 Galapagos guano, 80. 
 
 Garbage tankage, see tankage, gar- 
 bage. 
 
 Garola, 353. 
 
 Gas-house lime, see gas lime. 
 
 Gas-lime, 314. 
 
 Gasparin, 310, 311. 
 
 Genter, see Jordan. 
 
 Gerlach, 186, 189, 288. 
 
 German potash salts, discovery of, 
 in Germany, 7 ; impurities asso- 
 ciated with, 7. 
 
 Giglioli, 47, 352 ; and Rousset, 356. 
 
 Gilbert, see Lawes. 
 
 Gilchrist, see Thomas. 
 
 Gile, 286, 302, 321, 332. 
 
 Girard, 361 ; see Miintz. 
 
 Glue, substances containing, some- 
 times rendered less available by 
 steaming, 106. 
 
 Gluten feed, composition of, 111. 
 
 Godechens, 230, 231. 
 
 Goessmann, 85, 92, 100, 107, 109 
 
 Gohn, 165. 
 
 Goodale, 342. 
 
 Goodwin, see Russell. 
 
 Grandeau, 273, 311. 
 
 Granite, amount of soda in, 334. 
 
 Granitic soil, soon shows need of 
 potash, 338. 
 
 Greensand, 242 ; a sea-bottom de- 
 posit, 242 ; composition of, 242 ; 
 
374 
 
 INDEX 
 
 decomposed by hydrochloric acid, 
 242 ; has value as a manure, 242 ; 
 may exchange one base for an- 
 other, 243 ; of possible magmatic 
 origin, 242 ; proposed fusion with 
 calcium chlorid, 243 ; slow in its 
 manurial action, 242. 
 
 Griffiths, 247, 339. 
 
 Guanin in guano, 76. 
 
 Guano, a poorly balanced manure, 
 83 ; adulteration of, 81 ; Baker 
 Island, 77; Chincha Island, 78, 
 81 ; chemical composition of, 76, 
 77, 83 ; Colombian, 80 ; color of, 
 78 ; composition of, affected by 
 climate, 77 ; distribution and 
 sources of, 79, 80, 81 ; early ex- 
 periments with, 75 ; early use of, 
 75 ; effect of, on physical char- 
 acter of soil, 79 ; Galapagos, 80 ; 
 introduction into England, 6 ; 
 introduction into Europe, 75 ; 
 Ichaboe, 81 ; Lobos, 81 ; manner 
 of using, 82 ; Maracaibo, 80 ; 
 Mejillones, 77 ; nature of, 76 ; 
 origin of name of, 75 ; Peruvian, 
 81 ; physical character of, 78 ; 
 rectified or dissolved, 81. 
 
 Guano, bat, appearance of, 83 ; 
 chemical composition of, 84 ; 
 distribution of, 84 ; needs sup- 
 plementing, 85 ; precautions in 
 purchasing, 84 ; unlike others, 
 83 ; where found, 84. 
 
 Guano, fish, long used as a manure, 
 86 ; special processes for prepar- 
 ing, 86, 87 ; use of, as fertilizer, 
 86 ; wastes in Japan, 87 ; wastes 
 in Newfoundland, 87. 
 
 Guano, horse foot, see horse-foot 
 guano. 
 
 Guano, phosphatic, 179, 180. 
 
 Guano, whale, 89, 90 ; fish avail- 
 ability of, 90 ; how applied, 90. 
 
 Guitteau, see Coutejean. 
 
 Guper, 35. 
 
 Gypsum, as a renovator of black- 
 alkali soils, 314 ; aids nitrifica- 
 tion in alkaline media, 313, 314; 
 
 an indirect fertilizer, 311 ; as a 
 preservative of ammonia, 32, 33 ; 
 as an oxidizing agent, 313 ; beets 
 helped by, in Rhode Island, 310; 
 early use of, 309 ; effect of, on the 
 solubility of lime, 314; factors 
 determining choice of, 312, 313 ; 
 Gasparin's experiments with, 310, 
 311 ; good effect of, on clover and 
 other plants, 309, 310; holds 
 ammonia, 313 ; in gas-lime, 314 ; 
 liberates potash, 311 ; may be 
 changed to calcium carbonate in 
 the soil, 312 ; may sometimes 
 help by furnishing sulfur, 312 ; 
 methods of applying, 312 ; poorer 
 than lime for acid soils, 311, 312 ; 
 should be used in excess, 32, 33 ; 
 sources of, 309 ; sources of, in 
 soils, 309. 
 
 Hair, composition of, 103. 
 
 Hair, tannery, composition of, 
 
 103. 
 Hall, 29, 60, 61, 134, 140, 154, 155, 
 
 258, 259, 286, 363. 
 Hardy, 84. 
 Hares and rabbits, composition of 
 
 waste of, 104 ; waste of, 104. 
 Hart and Peterson, 287, 358, 359. 
 Hartwell, 328; and Pember, 173, 
 
 243, 347 ; also see Wheeler. 
 Headden, 134, 135; and Sackett, 
 
 134. 
 Heiden, 11, 13, 79, 100, 166, 277, 
 
 278. 
 Heinrich, 122. 
 Hellriegei; 105, 347 ; and Wilfarth, 
 
 5, 254, 347. 
 Hendrick, 194. 
 Hen manure, see manure. 
 Herapoth, 352. 
 High-grade sulfate of potash, see 
 
 sulfate of potash, 
 Hilgard, 31, 135, 314, 316, 324, 328, 
 
 336. 
 Hiller, 49. 
 Hippuric acid, 21 ; decomposition 
 
 of, in manure, 46. 
 
INDEX 
 
 375 
 
 Hochmoor, see peat. 
 
 Hog manure, see manure. 
 
 Hoof meal, after steaming, 100 ; 
 and horn meal, adulteration of, 
 1.00 ; composition of, 99 ; effi- 
 ciency of, 100 ; nitrogen content 
 of, 100; preparation of, 99. 
 
 Hoof meal and horn meal mixed, 
 99, 100 ; nitrogen availability in, 
 122. 
 
 Hopkins, 173. 
 
 Horn and hoof meal, adulteration 
 of, 100. 
 
 Horn meal, 99; and hoof meal 
 mixed, 99, 100 ; composition of, 
 99 ; keratin in, 99. 
 
 Horse-foot guano, composition of, 
 92 ; lacking in phosphoric acid, 
 92 ; nitrogen of, highly available, 
 92 ; poor in potash, 92. 
 
 Horse manure, see manure. 
 
 Horseradish, sulfur in, 357. 
 
 Hosaus, 160. 
 
 Hoyermann, 192. 
 
 Hudig, 297, 353. 
 
 Hughes, 359. 
 
 Human excrement, 10. 
 
 Humboldt, Alexander von, 75. 
 
 Hurst, see Cameron. - 
 
 Hutchinson, see Russell. 
 
 Huttemann, W., 35. 
 
 Hydrated lime, 263 ; becomes re- 
 carbonated, 264 ; nature of, 263 ; 
 production of, 263. 
 
 Hydrogen, fermentation in manure, 
 43. 
 
 Ichaboe guano, 81 ; composition of, 
 81. 
 
 Ichthyosaurus, 179. 
 
 Idaho phosphates, 184. 
 
 Indol, 49. 
 
 Infusoria, soil, destroy microbes, 
 363. 
 
 Ingenhaus, 2. 
 
 Insects, 108 ; composition of, 108. 
 
 Insoluble phosphoric acid, see phos- 
 phoric acid. 
 
 Irish moss, 66, 73, 231. 
 
 Iron, carbonate, changes color on 
 oxidizing, 352 ; generally present 
 in soils in sufficient quantities, 
 351 ; higher salts of, reduced 
 under anaerobic conditions, 351 ; 
 lack of, in plants, causes chlorosis, 
 351 ; lower salts of, oxidized on 
 draining, 352 ; need of, by plants 
 easily demonstrated, 351 ; salts, 
 toxic, broken up by liming, 352 ; 
 sulfids bad in gravels or sands 
 used as coverings for bogs, 352 ; 
 vital to the higher plants, 351. 
 
 Iron and aluminium silicates some- 
 times objectionable in phos- 
 phates, 221. 
 
 Iron phosphate, 185, 189, 190; 
 formed in soils, 188. 
 
 James, 231. 
 
 Jamieson, 247. 
 
 Jenkins, 231. 
 
 Jentys, 47. 
 
 Jodin, 360. 
 
 Johnson, S. W., 102, 105, 122, 344. 
 
 Joly, 210. 
 
 Jordan and Genter, 344. 
 
 Julie, 33. 
 
 Kainit, as a preservative of manure, 
 34 ; composition of, 237. 
 
 Karmrodt, 77. 
 
 Karsten, 234. 
 
 Katayama, 331. 
 
 Kellerman and Robinson, 285. 
 
 Kelley, 353, 355. 
 
 Kellner, 91, 115, 120, 169. 
 
 Kelp, 65, 66, 67, 231. 
 
 Kette, 40. 
 
 Kieserit, 332 ; as a preservative of 
 manure, 34 ; composition of, 237. 
 
 King, 257, 341. 
 
 King-crab, 92. 
 
 Klaproth, see Vaquelin. 
 
 Knop, 6, 319, 323. 
 
 Koch and Pettit, 265. 
 
 Konowalo, 331. 
 
 Kunkle, 165. 
 
 Kuntze, 135. 
 
374 
 
 INDEX 
 
 decomposed by hydrochloric acid, 
 242 ; has value as a manure, 242 ; 
 may exchange one base for an- 
 other, 243 ; of possible magmatic 
 origin, 242 ; proposed fusion with 
 calcium chlorid, 243 ; slow in its 
 manurial action, 242. 
 
 Griffiths, 247, 339. 
 
 Guanin in guano, 76. 
 
 Guano, a poorly balanced manure, 
 83 ; adulteration of, 81 ; Baker 
 Island, 77; Chincha Island, 78, 
 81 ; chemical composition of, 76, 
 77, 83 ; Colombian, 80 ; color of, 
 78 ; composition of, affected by 
 climate, 77 ; distribution and 
 sources of, 79, 80, 81 ; early ex- 
 periments with, 75 ; early use of, 
 75 ; effect of, on physical char- 
 acter of soil, 79 ; Galapagos, 80 ; 
 introduction into England, 6 ; 
 introduction into Europe, 75 ; 
 Ichaboe, 81 ; Lobos, 81 ; manner 
 of using, 82; Maracaibo, 80; 
 Mejillones, 77 ; nature of, 76 ; 
 origin of name of, 75 ; Peruvian, 
 81 ; physical character of, 78 ; 
 rectified or dissolved, 81. 
 
 Guano, bat, appearance of, 83 ; 
 chemical composition of, 84 ; 
 distribution of, 84 ; needs sup- 
 plementing, 85 ; precautions in 
 purchasing, 84 ; unlike others, 
 83 ; where found, 84. 
 
 Guano, fish, long used as a manure, 
 86 ; special processes for prepar- 
 ing, 86, 87 ; use of, as fertilizer, 
 86 ; wastes in Japan, 87 ; wastes 
 in Newfoundland, 87. 
 
 Guano, horse foot, see horse-foot 
 guano. 
 
 Guano, phosphatic, 179, 180. 
 
 Guano, whale, 89, 90 ; fish avail- 
 ability of, 90 ; how applied, 90. 
 
 Guitteau, see Coutejean. 
 
 Guper, 35. 
 
 Gypsum, as a renovator of black- 
 alkali soils, 314 ; aids nitrifica- 
 tion in alkaline media, 313, 314; 
 
 an indirect fertilizer, 311 ; as a 
 preservative of ammonia, 32, 33 ; 
 as an oxidizing agent, 313 ; beets 
 helped by, in Rhode Island, 310 ; 
 early use of, 309 ; effect of, on the 
 solubility of lime, 314; factors 
 determining choice of, 312, 313 ; 
 Gasparin's experiments with, 310, 
 311 ; good effect of, on clover and 
 other plants, 309, 310; holds 
 ammonia, 313; in gas-lime, 314; 
 liberates potash, 311 ; may be 
 changed to calcium carbonate in 
 the soil, 312 ; may sometimes 
 help by furnishing sulfur, 312 ; 
 methods of applying, 312 ; poorer 
 than lime for acid soils, 311, 312 ; 
 should be used in excess, 32, 33 ; 
 sources of, 309 ; sources of, in 
 soils, 309. 
 
 Hair, composition of, 103. 
 
 Hair, tannery, composition of, 
 
 103. 
 Hall, 29, 60, 61, 134, 140, 154, 155, 
 
 258, 259, 286, 363. 
 Hardy, 84. 
 Hares and rabbits, composition of 
 
 waste of, 104 ; waste of, 104. 
 Hart and Peterson, 287, 358, 359. 
 Hartwell, 328; and Pember, 173, 
 
 243, 347 ; also see Wheeler. 
 Headden, 134, 135; and Sackett, 
 
 134. 
 Heiden, 11, 13, 79, 100, 166, 277, 
 
 278. 
 Heinrich, 122. 
 Hellriegei; 105, 347 ; and Wilfarth, 
 
 5, 254, 347. 
 Hendrick, 194. 
 Hen manure, see manure. 
 Herapoth, 352. 
 High-grade sulfate of potash, see 
 
 sulfate of potash, 
 Hilgard, 31, 135, 314, 316, 324, 328, 
 
 336. 
 Hiller, 49. 
 Hippuric acid, 21 ; decomposition 
 
 of, in manure, 46. 
 
INDEX 
 
 375 
 
 Hochmcor, see peat. 
 
 Hog manure, see manure. 
 
 Hoof meal, after steaming, 100 ; 
 and horn meal, adulteration of, 
 100 ; composition of, 99 ; effi- 
 ciency of, 100 ; nitrogen content 
 of, 100; preparation of, 99. 
 
 Hoof meal and horn meal mixed, 
 99, 100 ; nitrogen availability in, 
 122. 
 
 Hopkins, 173. 
 
 Horn and hoof meal, adulteration 
 of, 100. 
 
 Horn meal, 99 ; and hoof meal 
 mixed, 99, 100 ; composition of, 
 99 ; keratin in, 99. 
 
 Horse-foot guano, composition of, 
 92 ; lacking in phosphoric acid, 
 92 ; nitrogen of, highly available, 
 92 ; poor in potash, 92. 
 
 Horse manure, see manure. 
 
 Horseradish, sulfur in, 357. 
 
 Hosaus, 160. 
 
 Hoyermann, 192. 
 
 Hudig, 297, 353. 
 
 Hughes, 359. 
 
 Human excrement, 10. 
 
 Humboldt, Alexander von, 75. 
 
 Hurst, see Cameron. • 
 
 Hutchinson, see Russell. 
 
 Hiittemann, W., 35. 
 
 Hydrated lime, 263 ; becomes re- 
 carbonated, 264 ; nature of, 263 ; 
 production of, 263. 
 
 Hydrogen, fermentation in manure, 
 43. 
 
 Ichaboe guano, 81 ; composition of, 
 81. 
 
 Ichthyosaurus, 179. 
 
 Idaho phosphates, 184. 
 
 Indol, 49. 
 
 Infusoria, soil, destroy microbes, 
 363. 
 
 Ingenhaus, 2. 
 
 Insects, 108; composition of, 108. 
 
 Insoluble phosphoric acid, see phos- 
 phoric acid. 
 
 Irish moss, 66, 73, 231. 
 
 Iron, carbonate, changes color on 
 oxidizing, 352 ; generally present 
 in soils in sufficient quantities, 
 351 ; higher salts of, reduced 
 under anaerobic conditions, 351 ; 
 lack of, in plants, causes chlorosis, 
 351 ; lower salts of, oxidized on 
 draining, 352 ; need of, by plants 
 easily demonstrated, 351 ; salts, 
 toxic, broken up by liming, 352 ; 
 sulfids bad in gravels or sands 
 used as coverings for bogs, 352 ; 
 vital to the higher plants, 351. 
 
 Iron and aluminium silicates some- 
 times objectionable in phos- 
 phates, 221. 
 
 Iron phosphate, 185, 189, 190; 
 formed in soils, 188. 
 
 James, 231. 
 
 Jamieson, 247. 
 
 Jenkins, 231. 
 
 Jentys, 47. 
 
 Jodin, 360. 
 
 Johnson, S. W., 102, 105, 122, 344. 
 
 Joly, 210. 
 
 Jordan and Genter, 344. 
 
 Julie, 33. 
 
 Kainit, as a preservative of manure, 
 34 ; composition of, 237. 
 
 Karmrodt, 77. 
 
 Karsten, 234. 
 
 Katayama, 331. 
 
 Kellerman and Robinson, 285. 
 
 Kelley, 353, 355. 
 
 Kellner, 91, 115, 120, 169. 
 
 Kelp, 65, 66, 67, 231. 
 
 Kette, 40. 
 
 Kieserit, 332 ; as a preservative of 
 manure, 34 ; composition of, 237. 
 
 King, 257, 341. 
 
 King-crab, 92. 
 
 Klaproth, see Vaquelin. 
 
 Knop, 6, 319, 323. 
 
 Koch and Pettit, 265. 
 
 Konowalo, 331. 
 
 Kunkle, 165. 
 
 Kuntze, 135. 
 
376 
 
 INDEX 
 
 Lachowiez, 188. 
 
 Lahn phosphate, see Nassau. 
 
 Laminaria digitata, 66, 67, 230. 
 
 Laminaria saccharina, 65, 66, 230. 
 
 Larbaletrier and Malpeaux, 318. 
 
 Lawes, 75, 120 ; and Gilbert, 4, 5, 
 6, 12, 158. 
 
 Leather meal, nitrogen availability 
 in, 120, 122. 
 
 Leather waste, 100 ; availability 
 of, 101 ; improved greatly by wet 
 acid treatment, 100 ; less valu- 
 able than it appears, 102 ; pre- 
 pared, composition of, 101 ; 
 roasted, 101 ; steamed, treat- 
 ment of, 101 ; treatment of, with 
 carbonates of the alkalies, 102. 
 
 Lecanu, 11. 
 
 Le Clerc, 352. 
 
 Legumes, best lime-magnesia ratio 
 for, 331 ; manurial value of, 
 known to Varro and Columella, 1. 
 
 Lehmann, 11, 160. 
 
 Ley, H., 248, 328. 
 
 Liebig, 3, 4, 6, 7, 79. 
 
 Liernur process, for the preserva- 
 tion of human excrement, 15. 
 
 Lime, action of, on feldspar, how 
 weakened, 288 ; action of, on 
 worms and slugs, 267 ; aids hold- 
 ing power of soil for bases, 289 ; 
 amounts to apply, 292 ; analysis 
 of burned, 262 ; application in 
 Pennsylvania experiments, exces- 
 sive, 276 ; as a liberator of potash, 
 286 ; beneficial effects accounted 
 for, 307 ; brings in nutritious 
 grasses and clovers, 293 ; by 
 addition to clay said to form 
 zeolites, 289 ; carbonate less 
 dangerous on sandy soils than 
 magnesian carbonate, 285 ; caus- 
 tic, attacks powdered quartz, 
 289 ; cheapest basic treatment 
 for soils, 270 ; chemical methods 
 for determining need of, 270, 271 ; 
 compounds transformed by 
 plants, 295 ; corrects effect of 
 excess of magnesia, 261 ; dolo- 
 
 mitic, 263 ; effect of, on ammoni- 
 fication, 262 ; effect of, on air cir- 
 culation in soils, 265 ; effect of, 
 on certain diseases, 262 ; effect 
 of, on denitrification, 262; 265; 
 effect of, on dry spot of oats, 297 ; 
 effect of, on microscopic flora of 
 soils, 262 ; effect of, on nitrifica- 
 tion, 262 ; effect of, on nitrogen 
 assimilation, 262 ; effect of, on 
 nitrogen availability, 264, 265 ; 
 effect of, on plants as compared 
 with gypsum, 309, 310 ; effect of, 
 on potato scab, 296, 299, 301, 
 302 ; effect of, on size and yield 
 of potatoes, 303 ; effect of, on 
 soil texture, 265 ; effect of, on 
 tobacco root rot, 297 ; effect of, 
 on vegetable decay, 271, 272 ; 
 effect of, on water, movement, 
 266 ; essential to plant growth, 
 261 ; excessive use of, to be 
 avoided, 292 ; hastens crop ma- 
 turity, 304, 305 ; hydrated, 263 ; 
 indirect action of, illustrated, 286, 
 287, 289 ; indirect manurial 
 action of, 286 ; kinds of, used in 
 agriculture, 262, 263 ; knowledge 
 of, perpetuated in monasteries, 
 2 ; lessens club-foot disease, 
 297 ; liberates phosphoric acid, 
 267 ; loses carbon dioxid in burn- 
 ing, 262 ; losses, of, from soils, 
 by leaching, 289, 290 ; magne- 
 sian, 263 ; may cause injury to 
 pineapples, 302 ; may improve 
 light soils physically, 266 ; mis- 
 cellaneous sources of, 264 ; 
 needed for some plants, but bad 
 for others, 306 ; not required to 
 extent shown by some methods, 
 271 ; occurrence of, 261 ; oxalate 
 of, changed into carbonate in 
 soils, 295 ; oxalate of, in plants, 
 295 ; potash fixed after liberation 
 by, 287, 288 ; practical applica- 
 tion of, 292, 293 ; precipitated 
 out in the plant as calcium oxa- 
 late, 330 ; pure, compared with 
 
INDEX 
 
 377 
 
 magnesian, 293, 294 ; require- 
 ments of different plants for, 307, 
 308 ; should usually be intro- 
 duced into the soil, 293 ; slaked, 
 becomes quickly carbonated, 277, 
 278 ; slaked, highly beneficial in 
 Rhode Island, 276, 277; some- 
 times excreted from plants as 
 carbonate, 330 ; treatment of 
 excrement with, 16 ; use of, in 
 connection with phosphates, 266, 
 267 ; use of, on mossy land, 293 ; 
 use of, on pastures, 293 ; waste, 
 from industries, 314, 315; where 
 to spread, on the surface, 293. 
 
 Lime, builders, see burned lime. 
 
 Lime, burned, see burned lime. 
 
 Lime-magnesia, ratios best for 
 barley, 331 ; beans, 332 ; buck- 
 wheat, 331 ; cabbages, 331 ; 
 cereals, 331 ; flax, 332 ; legumes, 
 331 ; maize, 331 ; mulberry 
 leaves, 331 ; oats, 331 ; rice, 331 ; 
 tobacco, 332; wheat, 331. 
 
 Lime-nitrogen, 161. 
 
 Lime, slaked, avoidance of use of, 
 to conserve humus not always 
 wise, 273, 274, 275; compared 
 with calcium carbonate and marl, 
 278, 289, 280; earlier believed 
 not to carbonate quickly, 277, 
 278 ; effect of, on potato scab, 
 301 ; errors of Heiden concern- 
 ing, 277, 278; if used properly, 
 does not injure soils, 275 ; in- 
 creases nitrogen content of humus, 
 272, 273 ; good results from, 276, 
 277 ; rotations of crops essential 
 in connection with use of, 273. 
 
 Lime, slaked and burned, concern- 
 ing their expulsion of ammonia 
 from soils, 282, 283 ; influence of, 
 on nitrification, 283, 284, 285 ; in- 
 troduction of, into acid peat sub- 
 soils, 281 ; large amounts of 
 slaked lime check nitrification, 
 284; penetration of, into soils, 
 280, 281, 282 ; views of European 
 authorities concerning, 280. 
 
 Lime and magnesia, percentage of, 
 in crops and relation of, to yields, 
 329, 330. 
 
 Lime-kiln ashes, composition of, 
 228. 
 
 Lime-magnesia ratio found by Gile 
 to vary widely without ill effects, 
 332. 
 
 Lime rock, see burned lime. 
 
 Limestone, see burned lime. 
 
 Limestone, burned, 263 ; changes 
 produced in, by burning, 262 ; 
 composition of, 263 ; distribu- 
 tion of, 261 ; dolomitic, 263 ; 
 effect of, on soils, 261. 
 
 Limestone, coarse, compared with 
 fine limestone, 290, 291 ; com- 
 pared with marl, 290, 291. 
 
 Limestone, magnesian, 332. 
 
 Liming, need of, suggested by soil 
 acidity, 268. 
 
 Limulus Americanus, 92. 
 
 Linseed meal, composition of, 110; 
 nitrogen availability in, 122. 
 
 Lipman, 124, 285, 286. 
 
 Liquors, dark, in leachings of dung, 
 52. 
 
 List, 36. 
 
 Litmus paper, action of cotton on, 
 268 ; action of finely divided 
 material on, 268, 269 ; reliability 
 of, questioned, 268, 269. 
 
 Litter, absorbent power of different 
 kinds of, for water and ammonia, 
 27, 31 ; ammonification of, 47; 
 amounts of, to use, 26, 27 ; as an 
 absorbent, 26 ; conserving power 
 of, 28 ; cotton waste as, 28 ; in- 
 fluence of, on manure, 19 ; leaves 
 as, 27 ; microorganisms in, 36 
 mosses as, 27 ; needles of conif- 
 erous trees as, 27 ; oat straw as 
 27 ; pea straw as, 27 ; peat as 
 27, 31 ; sawdust as, 27, 31 ; soil 
 as, 27, 31 ; spent tan as, 27 
 wheat straw as, 27. 
 
 Lobos guano, 83, 179 ; composition 
 of, 179. 
 
 Lobster refuse, 92; composition of, 92. 
 
378 
 
 INDEX 
 
 Loew, O., 246, 253, 285, 286, 294, 
 316, 319, 321, 322, 323, 325, 330, 
 363, 366 ; and Sawa, 354, 356. 
 
 Loges, 143. 
 
 Lovejoy and Bradley, 126. 
 
 Lucanus, see Birner. 
 
 Lupines, varying effect of lime on, 
 308. 
 
 Macrocystis purifera, 74. 
 
 Maercker, 143, 157 ; and Schneide- 
 wind, 30. 
 
 Magnesia, a carrier of phosphorus 
 in the plant, 316 ; aids in the 
 translocation of starch, 316; and 
 lime ratios in the soil, 321, 322, 
 323 ; conflicting ideas concerning 
 the action of, 317, 318, 319; 
 essential to plant growth, 317; 
 functions of, in the plant, 316, 
 317 ; in Japanese soils, 321, 322 ; 
 in Ohio soils, 322 ; lime ratio, 
 method of determining, in soils, 
 323 ; quantities in different parts 
 of plants, 323 ; sources of, for 
 fertilizer purposes, 332 ; theory 
 of Loew concerning, 319, 320, 321. 
 
 Magnesia, caustic, danger in using 
 for a time, 324 ; gave good results 
 the second year, 324 ; toxic at 
 first, 326. 
 
 Magnesia and lime in relation to 
 yields, 329, 330. 
 
 Magnesian lime, more dangerous 
 on light than on heavy .soils, 327 ; 
 possible danger in using, 326, 
 327 ; precautions in use of, 
 294. 
 
 Magnesian limestone, 332. 
 
 Magnesite, 332. 
 
 Magnesium carbonate, aids am- 
 monification of cotton-seed meal, 
 285 ; artificial, more soluble in 
 carbonated water than calcium 
 carbonate, 327 ; depresses am- 
 monification of dried blood, 285 ; 
 may cause injury by its alkaline 
 action, 327 ; natural, highly in- 
 soluble, 328 ; newly >>rmed, a 
 
 quicker corrective of acidity than 
 dolomite or magnesite, 328, 329 ; 
 solubility of artificial, 329 ; solu- 
 bility of natural, 327, 328. 
 
 Magnesium chlorid, concerning the 
 alleged toxic action of, 323 ; ex- 
 cessive amounts of, injurious, 
 323 ; not always poisonous, 324, 
 325 ; studies of, by Wheeler and 
 Hartwell, 324, 325, 326. 
 
 Magnesium fluor-apatite, 178; see 
 Wagnerite. 
 
 Mago, 1. 
 
 Maize, best lime-magnesia ratio for, 
 331 ; effect of manganese on, 
 355. 
 
 Malpeaux, see Larbaletrier. 
 
 Malt sprouts, composition of, 110. 
 
 Manganese, amounts of, safe to use 
 per acre, 353 ; beneficial effects 
 of, may be due to promoting 
 oxidation, 355 ; cannot fully re- 
 place iron in plant nutrition, 355, 
 356 ; change in oxidation of, 
 caused by roots, 355 ; dioxid 
 found adhering to roots, 355 ; 
 effect of, on carrots, 355 ; effect 
 of, on kidney beans, 355 ; effect 
 of, on potatoes, 355 ; effect of, on 
 wheat, 355 ; exerts bleaching 
 action on chlorophyl, 354 ; help- 
 ful to maize, only in small 
 amounts, 355 ; in Hawaiian soils, 
 353 ; in plants studied by Le 
 Clerc, 352 ; increases oxidase 
 and peroxidase reactions, 354 ; in- 
 creases yields of corn and wheat, 
 
 352 ; may aid chlorophyl develop- 
 ment, 355, 356 ; noted in plants 
 by Herapoth, 352 ; plants unlike 
 in endurance of, 353 ; presence 
 of, in plants shown by Scheele, 
 352 ; promotes development of 
 plants grown in dilute solutions, 
 354; restores "oat-sick" soils, 
 
 353 ; review of experiments with, 
 in plant nutrition, 356 ; salts of, 
 increased growth of flax, 352, 
 353 ; salts must be used cau- 
 
INDEX 
 
 379 
 
 tiously, 355 ; wide variations in 
 amount of, in plants and soils, 
 353, 354. 
 
 Mangon, M. Herve, 72. 
 
 Manure, amids in, 29 ; ammonia in, 
 29 ; amount of cellulose in, 41 ; 
 amount of pentosans in, 41 ; 
 amount of starch in, 41 ; anti- 
 septics disadvantageous as pre- 
 servatives of, 37 ; barn-yard, 19 ; 
 denitrification in, aided by certain 
 substances, 57, 58 ; denitrifica- 
 tion in, greater if used abun- 
 dantly, 58, 59 ; effect of chloro- 
 form on, 40 ; effect of heating on, 
 40 ; effect of, on potato scab, 301 ; 
 farm, 19 ; farm animals often 
 kept on, 29 ; favors disintegra- 
 tion of old sod, 63, 64 ; immediate 
 incorporation of, with soil desir- 
 able, 56 ; importance of strep- 
 tococci in, 37 ; influence of litter 
 on, 19 ; lacks effectiveness when 
 fresh, 52 ; lasting qualities of, 60, 
 61 ; liquid, preservation of, 53 ; 
 losses of, in heaps and broad- 
 casted, 56, 57 ; losses from, in- 
 creased by bacteria from intes- 
 tinal tract, 51 ; losses from, less 
 in later stages of decomposition, 
 51, 52 ; losses from, lessened, 
 when moist and compact, 50, 51 ; 
 losses from, lessened by packing 
 and trampling, 28 ; losses of 
 sugar in, 41 ; molds in, 39 ; 
 nature and cause of losses occur- 
 ring in, 50 ; necessity of moisture 
 in, 53 ; practical utilization of, 
 55 ; reason for even spreading of, 
 63 ; stable, 19 ; storage of, versus 
 direct application of, 55, 56 ; 
 supplemented profitably by chem- 
 ical fertilizers, 61, 62; time 
 to spread, 57 ; treatment of, in 
 Europe, 53 ; types of micro- 
 organisms in, 37 : use of coarse, 
 62, 63; waste of, by "fire- 
 fanging " and otherwise, 20; 
 yeasts in, 39. 
 
 Manure, cow, adapted to certain 
 greenhouse plants, 22 ; amount 
 of, produced per cow, 23 ; chemi- 
 cal composition of, 22 ; number 
 of microorganisms in, 35 ; often 
 improved by mixing with horse 
 manure, 22. 
 
 Manure, hen and pigeon, composi- 
 tion of, 25 ; need supplementing, 
 26 ; of superior value, 25 ; solid 
 and liquid of, voided together, 
 26 ; rich in nitrogen, 26. 
 
 Manure, hog, amount of, produced 
 per animal, 25 ; composition and 
 value of, 24. 
 
 Manure, horse, annual production 
 of, per animal, 22 ; composition 
 of, 21 ; ferments readily, 20, 21 ; 
 litter used with, 21, 22 ; losses 
 of, by "fire-fanging," 20, 28; 
 methods of storage of, 22 ; num- 
 ber of microorganisms in, 35. 
 
 Manures and chemicals, factors 
 governing use of, 62. 
 
 Manure, solid, ammonification of, 
 47. 
 
 Manure salts, 237, 332. 
 
 Manure, sheep, amount of, pro- 
 duced per animal, 24 ; composi- 
 tion of, 24 ; value of, 23. 
 
 Maracaibo guano, 80. 
 
 Marchand, 230, 231, 234. 
 
 Margraff, 165. 
 
 Marl, comparison of a low grade of, 
 with slaked lime, magnesia, and 
 oyster-shell lime, 279, 280 ; com- 
 pared with coarse and fine lime- 
 stone, 290, 291, 292; early use 
 of, 1. 
 
 Maturity of plants, effect of am- 
 monium sulfate on, 157. 
 
 Matzuschita, 36. 
 
 Mayer, A., 139, 160, 246, 247, 340, 
 343, 344, 345. 
 
 McFarland, 74. 
 
 Meat meal, Australian, 94; avail- 
 ability of, 95; composition of, 
 94, 95 ; little available for direct 
 use, 95. 
 
382 
 
 INDEX 
 
 Pagnoul, 247, 335, 336. 
 
 Palissy, 2. 
 
 Palmaer, 178. 
 
 Palmaer phosphate, 199 ; a dical- 
 cium phosphate, 199 ; experi- 
 ments with, in Sweden, 199 ; in- 
 ferior to basic slag meal for peat 
 soils, 200 ; on sandy and peat 
 soils the immediate and residual 
 effects of, equal those of super- 
 phosphate, 199 ; process of manu- 
 facture of, 199 ; solubility of, in 
 ammonium citrate, 199. 
 
 Passarini, 319, 337. 
 
 Pasteur, 45, 49. 
 
 Payen, 16; and Boussingault, 103. 
 
 Pea straw, absorbent power of, 27. 
 
 Pearl ash, see potassium carbonate. 
 
 Peat, absorbent power of, 27, 31; 
 see muck. 
 
 Peat soils, failure of lime to pene- 
 trate, 281. 
 
 Pectin, decomposition of, in manure, 
 43. 
 
 Peligot, 335. 
 
 Pelouze, see Dusart. 
 
 Pember, see Hartwell, see Wheeler. 
 
 Penicillium glaucum, 47. 
 
 Pentosans, amounts of, in manure, 
 41. 
 
 Pepsin method for determining 
 nitrogen availability, 123. 
 
 Permanganate method for deter- 
 mining nitrogen availability, 
 123. 
 
 Permanganate of potash, see potas- 
 sium permanganate. 
 
 Perraud, J., 362. 
 
 Peruvian guano, 81. 
 
 Petermann, 105, 115, 226. 
 
 Peterson, C, 99 ; see Hart. 
 
 Petlitt, 86. 
 
 Pettit, see Koch. 
 
 Pfeffer, 255, 342. 
 
 Pfeiffer, Th., 247. 
 
 Phonolite, of value as a fertilizer if 
 finely ground, 243 ; less valuable 
 than the German potash salts, 
 243. 
 
 Phosphates, artificial, from low- 
 grade phosphates, 200 ; artificial, 
 by bisulfate treatment, 201 ; 
 artificial, from aluminum phos- 
 phate, 201 ; choice of, affected 
 by the soil and crop, 225, 226, 
 227; den treatment of, 204; of 
 Belgium, 180; of France, 180 
 of Idaho, 184 ; of iron and alu- 
 minum, 185, 186, 188, 189, 190 
 of Montana, 184; of Northern 
 Africa, 181; of Portugal, 181: 
 of Russia, 181 ; of Tennessee 
 184 ; of the islands of the Pacific 
 180 ; of the Western States, 184 
 of Western States favorably situ- 
 ated, 185; of Wyoming, 184 
 other artificial, 200 ; Palmaer 
 199 ; relationship of the various 
 203 ; Wiborgh, 198 ; Wolter's, 199 
 
 Phosphate, acid, see acid phos- 
 phate. 
 
 Phosphate, dicalcium ; action of 
 water on, 211, 212; action of, 
 water on, increased by carbonic 
 acid, 212. 
 
 Phosphate, monocalcium ; action 
 of water on, 208, 210, 211 ; help 
 from liming after certain rever- 
 sions of, 216; reversion of, 215; 
 reversion of, with iron and alu- 
 minum oxids often serious, 219, 
 220 ; sometimes highly bene- 
 ficial, 219. 
 
 Phosphate, tricalcium; action of 
 water on, 212, 213, 214; action 
 of water on, increased by car- 
 bonic acid, 213 ; oxids of alu- 
 minum and iron in, are objec- 
 tionable for superphosphate 
 manufacture, 219 ; solubility and 
 decomposibility of, increased by 
 certain substances, 214. 
 
 Phosphates of Florida, black river 
 pebble, 183 ; bowlder, 183 ; com- 
 position of, 183 ; land pebble, 
 183 ; rock, 183. 
 
 Phosphates of South Carolina, age 
 of, 182 ; nodular, 182 ; of lime- 
 
INDEX 
 
 383 
 
 stone origin, 182; river, 182, 
 183. 
 Phosphatic guanos, 179, 180. 
 Phosphoric acid, free; definition 
 of term, 202 ; preparation of, 
 from tricalcium phosphate, 202. 
 Phosphoric acid, insoluble, 218. 
 Phosphoric acid, reverted; avail- 
 ability of, 217, 218 ; insoluble in 
 water, 217; not all from dical- 
 cium phosphate, 217. 
 Phosphoric acid, soluble; advan- 
 tages of, 215 ; after fixation may 
 be highly available to plants, 
 223 ; determination of, 214, 215 ; 
 reversion of, 216. 
 Phosphorite, see apatite. 
 Phosphorus, discovery of, 165; 
 found in bones, 165; found in 
 pyromorphite, 165; from phos- 
 phoric acid, 165; from seeds of 
 mustard and cress, 165 ; in apa- 
 tite, 165. 
 Phyllophora membrani folia, 66, 231. 
 Pigeon manure, see manure. • 
 Pineapple, manganese in, 354. 
 Pineapple chlorosis, caused by lime, 
 303; cured by applying iron 
 salts to the leaves, 302. 
 Pine sawdust, power of, to absorb 
 
 ammonia, 31. 
 Plant nutrition, first experiments 
 
 in, 2, 3. 
 Plants, miscellaneous, effect of 
 
 lime on, 307, 308. 
 Pogys, see Menhaden. 
 Polyhalit, 236. 
 Polyides rotundus, 66, 231. 
 Pomace, castor, composition of, 
 
 110. 
 Pond-weed family, 65. 
 Popp, 243. 
 
 Portuguese phosphates, 180. 
 Potash, absorption of, in soils, may 
 have several causes, 250, 251 ; 
 contracts with American fertilizer 
 manufactures, 235 ; deposits, oc- 
 currence, and distribution of salts 
 of, 235; deposits of salts of, in 
 
 Germany, 234, 235, 236, 237; 
 factors affecting absorption of, 
 251, 252, 253; fixed in soil after 
 liberation by lime, 287, 288 ; geo- 
 logical age of deposits of salts of, 
 236 ; history of the German salts 
 of, 234, 235; in ash of, Indian 
 corn cobs, 233 ; in potassium car- 
 bonate, 233 ; in potassium nitrate, 
 233 ; in sea-weeds, 66, 230, 231 ; 
 in soils, replaces other bases, 
 250 ; in tobacco stems, 232 ; 
 little loss of, by leaching, 251 ; 
 mines bought by Americans, 
 235 ; retention of, by soils, 250 ; 
 see potassium and potassium 
 salts. 
 Potassium, aids carbohydrate for- 
 mation, 253; as a neutralizer 
 and carrier in the plant, 255 ; 
 cannot be fully replaced by 
 sodium, 253 ; conserved in the 
 soil by sodium salts, 260; defi- 
 ciency of, more serious for some 
 crops than for others, 259, 260; 
 degree of replacement of, by 
 sodium depends upon the kind 
 of plant, 253 ; effect of a lack of, 
 on plants, 258 ; effect of an' 
 absence of, on Oxalis and Rumex, 
 344; effect of, on photosyn- 
 thesis, 254 ; effect of, on turgor, 
 255 ; essential to plant growth, 
 253 ; in alunite, 243 ; in feldspar, 
 243 ; in greensand, 242, 243 ; in 
 leucite, 243 ; in nepheline, 243 ; 
 in phonolite, 243 ; increases the 
 size of grain and amount of crop 
 of cereals, 254 ; increases the leg- 
 umes in mixed herbage, 258; 
 good effect of, on legumes, 257, 
 258; lessens vapor pressure in 
 soils with beneficial effect, 254 ; 
 may contribute a part to the 
 "luxury consumption" of the 
 plant, 256 ; may improve or in- 
 jure the physical condition of the 
 soil, 257 ; may increase surface 
 tension, 256, 257 ; may lessen 
 
384 
 
 INDEX 
 
 evaporation, 257 ; may stimulate 
 nitrogen assimilation by increas- 
 ing carbohydrates within the 
 plant, 258 ; necessary to combine 
 with organic acids, 344 ; not the 
 sole cure for clover sickness, 258 ; 
 permanganate, effect of, on soils, 
 363 ; salts act best in wet 
 seasons, 259 ; silicate, 241 ; vari- 
 ous functions of, 253. 
 
 Potassium carbonate, 241, 242 ; 
 sources of, 233 ; the chief im- 
 purities of, 233 ; valuable for 
 certain soils, 234. 
 
 Potassium chlorid, see muriate of 
 potash. 
 
 Potassium magnesium carbonate, 
 241 ; good for acid soils, 241. 
 
 Potassium nitrate, as an incrusta- 
 tion on some soils, 129 ; composi- 
 tion of, 130 ; impurities of, 131 ; 
 made artificially from nitrate of 
 soda, 131 ; made in artificial 
 niter beds, 130 ; manurial value 
 known by the year 1669, 6 ; 
 often economical as a fertilizer, 
 131, 233; sources of, 129, 130; 
 special uses of, 233 ; use of, per- 
 mits the avoidance of chlorin, 
 131. 
 
 Potassium salts, alleged ill effects 
 of chlorin of, 246, 247 ; German, 
 duration of deposition of, 238 ; 
 natural deposits of, elsewhere 
 than in Germany, 238 ; removed 
 from soil less readily than salts 
 of sodium, 246 ; tabulated analy- 
 ses of, 237. 
 
 Potassium sulfate, composition of, 
 237; fate of, in soil, 249; high 
 grade, 240 ; low grade, 240, 241 ; 
 reduced under anaerobic condi- 
 tions, 249. 
 
 Potatoes, effect of manganese on, 
 355 ; size and yields of, increased 
 by liming, 303, 304. 
 
 Potato scab, cause of, 299 ; effect 
 of barn-yard manure on, 301 ; 
 effect of calcium oxalate on, 301 ; 
 
 effect of calcium chlorid on, 301 ; 
 effect of calcium sulfate on, 
 301 ; effect of oxalic acid on, 
 301 ; effect of slaked lime on, 
 301 ; effect of sodium carbonate 
 on, 301 ; effect of wood ashes on, 
 301 ; fungus lives saprophytically 
 in the soil, 301. 
 
 Prianischnikov, 340. 
 
 Priestley, 2. 
 
 Proteins, sulfur in, 357. 
 
 Protozoa, according to Loew can- 
 not exist at the lower soil levels, 
 365 ; destroy bacteria, 40 ; de- 
 stroyed by certain substances, 
 40 ; destruction of, may explain 
 the benefit observed from firing 
 soils, 364 ; found at considerable 
 depths at Rothamsted, 365 ; 
 may destroy bacteria, 39 ; may 
 explain part of the gain from 
 deep plowing, 364, 365. 
 
 Pugh, 4. 
 
 Putrefaction, 49. 
 
 Pyridin or other similar compounds 
 have been found in soot, 108. 
 
 Pyrite in phosphates for superphos- 
 phate manufacture objectionable, 
 221. 
 
 Quiros, Allier & Co., 75. 
 
 Rabbits, see hares. 
 
 Raleigh, Lord, 125. 
 
 Redonda phosphate, 185. 
 
 Reed, 282, 316. 
 
 Reese, Jacob, 8. 
 
 Remy, 173. 
 
 Reuter, see Treadwell. 
 
 Reversion of phosphates, reactions 
 in course of, described, 218, 219, 
 220, 221. 
 
 Reverted phosphoric acid, see phos- 
 phoric acid, reverted. 
 
 Rhodymenia palmata, 66, 68, 230. 
 
 Rice, best lime-magnesia ratio for, 
 331. 
 
 Ricome, 340. 
 
 Ritthausen, 360. 
 
INDEX 
 
 385 
 
 Robinson, see Kellerman. 
 
 Rossi, 129. 
 
 Rousset, see Giglioli. 
 
 Russell, and Goodwin, 29 ; and 
 
 Hutchison, 40, 363. 
 Rye, best lime-magnesia ratio for, 
 
 331. 
 
 Sachs, 356. 
 
 Sackett, see Headden. 
 
 Salamone, 355. 
 
 Salfeld, 70. 
 
 Salm-Horstmar, 344. 
 
 Salt, common, 236 ; amount of, in- 
 jurious to crops, 334 ; large 
 amounts of, used in Great Britain, 
 339 ; may indirectly cause solu- 
 tion of vegetable matter, 340 ; 
 reacting with calcium carbonate 
 may produce sodium carbonates, 
 340. 
 
 Saltpeter, see potassium nitrate. 
 
 Saltpeter waste, composition of, 
 229 ; should be bought on analy- 
 sis, 229. 
 
 Salts, neutral, check dissociation, 
 328. 
 
 Salzthon, 236. 
 
 Sawa, see Loew. 
 
 Sawdust, absorbent power of, 27, 
 31. 
 
 Schacke, 243. 
 
 Scheele, 165, 352. 
 
 Schellmann, 47. 
 
 Schenck, see Strasburger. 
 
 Schneider, 186. 
 
 Schneidewind, 347 ; see Maercker. 
 
 Schreiber, see Smets. 
 
 Schreiner and Sullivan, 355, 356. 
 
 Schroeder, 354. 
 
 Schucht, 220. 
 
 Schultz, of Lupitz, 70, 248. 
 
 Sea weeds, analyses of, 66, 230, 231 ; 
 as affecting the need of lime, 72 ; 
 barilla from, 232 ; chemical com- 
 position of, 66, 230, 231 ; com- 
 pared with farm-yard manure, 
 72 ; composition of, at different 
 seasons, 67, 68 ; composting of, 
 
 73 ; effect of, on quality of crops, 
 70', 71 ; especial attention called 
 to, as a source of potash by the 
 famous German-American potash 
 contracts, 229 ; free from weed 
 seeds, 72 ; may injure hops, to- 
 bacco, and beets for sugar, 71 ; 
 not well balanced as a manure, 
 72 ; of chief importance in New 
 England, 68 ; often improved by 
 leaching, 71 ; often preferable to 
 stable manure, 70 : of the Atlan- 
 tic coast, 66, 230, 231; of the 
 Pacific coast, 74, 232 ; potash in, 
 66, 229, 230, 231; practical 
 utilization of, 70 ; produce 
 smooth potatoes, 70 ; quick in 
 their action, 71 ; rapidity of 
 growth of, 74 ; size of, 74 ; use 
 in Europe, 66 ; value of, known 
 to the ancients, 65 ; value of, 
 limited by cost of handling, 69, 
 70. 
 
 Sennebier, 2. 
 
 Severin, 33, 38, 40. 
 
 Seyffert, 122. . 
 
 Sheep manure, see manure. 
 
 Shimper, 255, 317. 
 
 Shoddy, composition of, 107 ; im- 
 proves the physical condition of 
 some soils, 107 ; use of, as a 
 manure, 107. 
 
 Shrimps, as a fertilizer, 91 ; lack- 
 ing in phosphoric acid, 91. 
 
 Siemens and Halske, 129. 
 
 Silene orientalis, 307. 
 
 Silica, an important constituent of 
 plants, 359 ; content of, in the 
 ash of plants sometimes 40 to 70 
 per cent, 359 ; deposition of, 
 checks sap diffusion, 360 ; may 
 favor migration of phosphoric 
 acid to the seed, 360 ; may have 
 special value for plants, 359 ; may 
 help form zeolites in soils, 359 ; 
 may help some plants but not 
 others, 360 ; may replace other 
 ingredients of plants in their 
 "luxury consumption," 360 ; may 
 
386 
 
 INDEX 
 
 support and protect the cell 
 wall, 359 ; not found by Jodin 
 to be essential to plants, 360. 
 
 Silicate of potash, a valuable fer- 
 tilizer, 241 ; analysis of, 241 ; 
 manufacture of, discontinued, 
 241 ; results with, in Massachu- 
 setts, 241. 
 
 Silk waste, nitrogen in, 104. 
 
 Sindermann, 17. 
 
 Sjollema, 335, 353 ; and De Ruyter 
 de Wild, 41. 
 
 Skatol, 49. 
 
 Skinner, 75. 
 
 Slugs, see worms. 
 
 Smets and Schreiber, 339. 
 
 Societa Generale per la Cianamide, 
 162. 
 
 Soda, absorbed by oats if potash is 
 deficient, 336 ; as an indirect 
 manure, 336 ; claimed to be 
 sometimes absent in plants, 335 ; 
 content of, in plants widely vari- 
 able, 336 ; favors passage of phos- 
 phoric acid into plants, 336 ; in 
 feldspar, 333 ; liberates magnesia, 
 337 ; presence of, in higher plants 
 practically universal, 334, 335 ; 
 said to be absent from potato 
 tubers, 335 ; universally distrib- 
 uted in nature, 334 ; used in the 
 fertilizers may increase the 
 amount in the plant, 336 ; see 
 sodium, and sodium salts. 
 
 Sodium, claimed by some to have 
 acted only indirectly, 346 ; 
 claimed to help by being a highly 
 soluble carrier of nitrogen and 
 phosphorus to the plant, 347 ; 
 concluded by Stohmann to be 
 essential to perfect plant develop- 
 ment, 344 ; conclusions of Jor- 
 dan and Genter concerning, 344, 
 345 ; if essential to plants, minute 
 quantities of, suffice, 344 ; in- 
 creased crops one half when po- 
 tassium was lacking, 346 ; may 
 partly replace potassium as a 
 combining and carrying agent in 
 
 the plant, 344 ; potassium re- 
 placed better by, than by cal- 
 cium, 345 ; see soda, and sodium 
 salts. 
 
 Sodium carbonate, a residual prod- 
 uct from the application of nitrate 
 of soda to soils, 340 ; effect of, 
 on potato scab, 301. 
 
 Sodium chlorid, amounts of, in- 
 jurious to crops, 334 ; an indirect 
 manure, 337 ; effect of, on potato 
 scab, 301 ; if it causes the for- 
 mation of carbonates, it may de- 
 flocculate soils, 341 ; in the air, 
 333 ; liberates potash, 337, 338 ; 
 seems to bring out the action of 
 phosphates and nitrates, 337 ; 
 sometimes aids by flocculating 
 soils, 341 ; sources of, in the air, 
 333. 
 
 Sodium nitrate, see nitrate of soda. 
 
 Sodium perchlorate, as an impurity 
 in nitrate of soda, 136, 137. 
 
 Sodium salts, benefit from, not 
 always explained by liberation 
 of potash, 349 ; benefit to crops 
 from applying, 338, 339, 340; 
 certain plants apparently not 
 benefited by, 347 ; doubled the 
 yield of mangel wurzels, 348 ; 
 effect of, dependent on various 
 conditions, 340, 341 ; effect of, 
 on osmotic pressure, 342 ; experi- 
 ments of Atterberg with, 345 ; 
 experiments with, in Rhode 
 Island, 348, 349, 350 ; facilitates 
 movement of water toward the 
 surface of the soil, 341 ; favor 
 diastatic action, 345 ; frequently 
 injurious, 339 ; increase phos- 
 phorus percentages in the plant, 
 338 ; increase surface tension, 
 341 ; indirect manurial action of, 
 impossible in water culture, 349 ; 
 in the experiments of Hellriegel 
 and Wilfarth, liberated potash, 
 348 ; in the plant, protect from 
 too rapid transpiration, 341 ; in 
 water culture helpful, 349 ; may 
 
INDEX 
 
 387 
 
 lessen evaporation, 341 ; mineral 
 sources of, 333, 334; more bene- 
 ficial to some plants than to 
 others, 339 ; of benefit to plants 
 in the field, 348 ; outside the 
 plant may lessen the water ab- 
 sorbed, 341 ; possible manurial 
 function of, 342 ; possible physio- 
 logical functions of, 342 ; prac- 
 tical significance of, in agriculture, 
 350 ; precautions in connection 
 with use of, in water culture, 349, 
 350 ; substitution of, for a part 
 of the potash in certain functions 
 of plants, 342, 343 ; see soda, and 
 sodium. 
 
 Soft phosphate, composition of, 184. 
 
 Sohngen, 45. 
 
 Soil, absorbent power of, 27, 31 ; 
 as an absorbent of ammonia, 30. 
 
 Soil disinfection, good effects of, 
 endure long, 365 ; may not be 
 generally applicable, 365. 
 
 Solid solution, definition of, 250. 
 
 Soluble phosphoric acid, see phos- 
 phoric acid, soluble. 
 
 Solution, solid, see solid solution. 
 
 Sombrero phosphate, 185. 
 
 Somme phosphates, 181. 
 
 Soot, benefits soils physically, 108 
 chemical composition of, 108 
 light, is best, 108 ; nature of, 107 
 often rich in ammonia, 107 
 rarely toxic, 108. 
 
 South Carolina phosphates, 182. 
 
 Spent tan, absorbent power of, 
 27. 
 
 Spruce, Norway, manganese in, 
 354. 
 
 Stable manure, see manure. 
 
 Stahl-Schroeder, 346. 
 
 Star-fish, composition of, 92, 93. 
 
 Stauf, 147. 
 
 Stead, 195. 
 
 Stockhardt, 289, 318. 
 
 Stohmann, 6, 344. 
 
 Stoklasa, 35, 41. 
 
 Storer, 92, 243, 267, 271, 288, 310, 
 319, 337. 
 
 Strasburger, 36 ; Noll, Schenck, and 
 Shimper, 317. 
 
 Stutzer, 150, 318. 
 
 Sulfate of ammonia, see ammonium 
 sulfate. , 
 
 Sulfate of potash, see potassium 
 sulfate. 
 
 Sulfate of potash, high grade, 240 ; 
 low grade, 237, 240. 
 
 Sulfate of potash and magnesia, 
 237. 
 
 Sulfur, amount of, in hay and 
 legumes, 358 ; carried in the rain- 
 fall, 359 ; essential to plant 
 growth, 357 ; important in essen- 
 tial oils, 357 ; in cress, 357 ; in 
 certain German potash salts, 
 
 357 ; in gypsum, 357 ; in horse- 
 radish, 357 ; in proteins, 357 ; in 
 superphosphate, 357 ; losses of, 
 by leaching at Rothamsted, 359 ; 
 may perhaps become depleted in 
 soils, 358 ; relation of, to phos- 
 phorus in the plant and soil, 358 ; 
 amounts of, removed by cabbages, 
 
 358 ; removed from soils in large 
 amounts by some crops, 358 ; re- 
 moved to the extent of 40 per 
 cent from soils long cropped, 358 ; 
 returned to soils in farm-yard 
 manures, 358 ; should be further 
 investigated, 359 ; supposed to be 
 seldom if ever deficient in soils, 
 357. 
 
 Sulfuric acid, as a preservative of 
 manure, 34. 
 
 Sullivan, see Schreiner. 
 
 Superphosphate, aids maturity and 
 starch production in potatoes, 
 227 ; as a preservative of manure,. 
 33 ; best adapted to what crops, 
 226, 227 ; care in the manufac- 
 ture of, 203, 204 ; double, cheap 
 to transport, 205; double, 37, 
 204, 205, 206 ; double, manufac- 
 ture of, 205 ; especially adapted 
 to the top-dressing of grass and 
 grain, 226 ; especially helpful, 
 with other ingredients, for sugar 
 
388 
 
 INDEX 
 
 beets, 227 ; fixation chiefly in 
 surface soil, 222 ; fixation of, in 
 soils rapid, 221, 222; flocculat- 
 ing action of, 225 ; free phos- 
 phoric acid in, 202 ; injury from, 
 rare, 223 ; made from various sub- 
 stances, 201 ; manufacture begun 
 by Lawes in the year 1842, 7; 
 may give inferior results on cer- 
 tain soils, 225 ; preparation of, 
 201, 202, 204. 
 
 Superphosphatgyps, 37. 
 
 Sutherst, 355. 
 
 Suzuki, 345. 
 
 Sylvanit, 236, 237 ; composition of, 
 237, 239. 
 
 Tacke, 243. 
 
 Takeuchi, 331. . 
 
 Tangle, 65, 66, 67, 230. 
 
 Tankage, availability of nitrogen 
 
 in, 122. 
 Tankage, bone, as a fertilizer, 96 ; 
 
 composition of, 96, 172 ; method 
 
 of employment of, 96 ; nature of, 
 
 95 ; value of nitrogen of, 96. 
 Tannery hair, composition of, 103. 
 Tennant, 319. 
 Tennessee phosphate, 184. 
 Teuthorn, 17. 
 Thaer, 3. 
 
 Thaxter, 299, 301. 
 Thiel, C, 104. 
 Thielavia basicola, 297. 
 Thiocyanates as an impurity in 
 
 ammonium sulfate, 147. 
 Thomas and Gilchrist, 191. 
 Thomas meal, see basic slag meal. 
 Thomas phosphate, see basic slag 
 
 meal. 
 Thomas phosphate powder, see 
 
 basic slag meal. 
 Thon, 17. 
 Thurneyssen, 87. 
 Tobacco, best lime-magnesia ratio 
 
 for, 332. 
 Tobacco stems, potash in, 232. 
 Toluene, 40 ; effect of, on soils, 
 
 363. 
 
 Toluene treatment of soils, de- 
 stroys protozoa, 364 ; increases 
 ammonification, 364; results of, 
 364. 
 
 Treadwell and Reuter, 327. 
 
 Tricalcium phosphate, see phos- 
 phate. 
 
 Tricresol, 40 ; effect of, on soils, 363. 
 
 Tull, Jethro, 2. 
 
 Turgor, effect of potassium on, 255. 
 
 Ullao, 75. 
 
 Ullmann, 247. 
 
 Urea, 29, 163 ; decomposition of, 
 in manure, 44, 45, 46. 
 
 Uric acid, decomposition of, in 
 manure, 47 ; in guano, 76. 
 
 Urine, amount of, produced per per- 
 son, 11 ; human, chemical com- 
 position of, 11, 12; microorgan- 
 isms essentially absent from, 36 ; 
 nitrification of, aided by calcium 
 sulfate, 285. 
 
 Urobacillus duclauxii, 46. 
 
 Urobacillus jakschii, 46. 
 
 Urobacillus pasteuri, 45. 
 
 Van Senus, 43. 
 
 Vauquelin and Klaproth, 165 ; see 
 
 Fourcroy. 
 Vega, Garcilaso de la, 75. 
 Viard, 211. 
 Vibrans, 230, 231. 
 Ville, 4, 317, 319. 
 Virgil, 1. 
 
 Vivianite, an iron phosphate, 188. 
 Voelcker, 139, 152, 158, 159, 251, 
 
 355. 
 Von Feilitzen, H., 200, 243. 
 Von Freudenreich, 35. 
 Von Raumer, E., .316, 319. 
 Von Wagner, L., 246, 323. 
 Von Wolff, E., 316. 
 Voorhees, 92, 100, 120. 
 
 Wachsmann, 345. 
 
 Wagner, 95, 120, 140, 157, 362; 
 
 and Dorsch, 116; 119, 143, 150, 
 
 152, 157, 346. 
 
INDEX 
 
 389 
 
 Wagnerite, 178. 
 Warrington, 131, 313, 362. 
 Water-slaked lime, see hydrated 
 
 lime. 
 Wavellite, an iron phosphate, 185. 
 Waxes and fats, decomposition of, 
 
 in manure, 44. 
 Way, 250. 
 
 Weiser and Zaitschek, 41. 
 Western phosphates, 184. 
 Whale, fat difficult to separate, 90 ; 
 
 glue sometimes used as a ferti- 
 lizer, 90 ; guano, 90. 
 Whale-bone, composition of, 90. 
 Whale waste, 88 ; composition of, 89. 
 Wheat, best lime-magnesia ratio 
 
 for, 331 ; effect of manganese on, 
 
 355. 
 Wheat straw, absorbent power of, 
 
 27, 31. 
 Wheeler and Hartwell, 4, 67, 105, 
 
 119, 230, 231, 232, 247, 256, 260, 
 
 324, 329, 336; Hartwell and 
 
 Pember, 349. 
 Whitney, M., 362. 
 Wiborgh phosphate, constitution 
 
 of, 198; now superseded by 
 
 Palmaer phosphate, 199. 
 
 Wilfarth, 4, 105, 260, 347; see 
 Hellriegel. 
 
 Wolff, 336, 360. 
 
 Wolter's phosphate, process of 
 manufacture of, 199 ; solubility 
 of, in citric acid, 199. 
 
 Wood ashes, composition of, 228. 
 
 Wool, composition of, 103. 
 
 Wool, waste, as a manure, 104 ; 
 composition of, 104 ; effect of 
 superheated steam on, 104 ; 
 Petermann's test of availabil- 
 ity of, possible errors in, 105 ; 
 soluble, not lost by leaching, 
 105. 
 
 Worms and slugs, action of lime on, 
 267, 268. 
 
 Wurtz, 243. 
 
 Wiitrich and Von Freudenreich, 
 35. 
 
 Wyoming, phosphates of, 184. 
 
 Yeasts in manure, 39. 
 
 Zaitschek, see Weiser. 
 
 Zoller, 336. 
 
 Zostera marina, 65, 69, 231. 
 
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 In order to adapt the volume to popular as well as professional readers the 
 text is printed in two different kinds of type. The larger contains the matter 
 which is essential to any intelligent student of the subject and which will be 
 found interesting by any farmer or man with a country place. In the smaller 
 type is contained the more strictly scientific and technical matter. 
 
 " Dr. Hilgard, by reason of his special and long-continued attention to the 
 chemistry of soils, and his intimate acquaintance with the subject, was pecu- 
 liarly well fitted for the task to which he applied himself in the preparation 
 of the present work. It is concise and yet exhaustive. Every phase of the 
 topic is thoroughly treated. Soils are discussed with relation to their origin, 
 properties, and composition as well as to the climate and their adaptability to 
 various crops and plant growths; also with regard to irrigation and fertiliza- 
 tion. A vast amount of scientific knowledge has been compressed into the 
 book, set forth in lucid style so as to be readily understood by any intelligent 
 reader. Technical terms are as far as possible avoided and the volume is 
 thoroughly practical. No farmer or fruit grower can afford to be without the 
 information contained in Soils. And while the work is necessarily expensive, 
 it is well worth the price." — The Evening Bee, Sacramento. 
 
 PUBLISHED BY 
 
 THE MACMILLAN COMPANY 
 
 64-66 Fifth Avenue, New York 
 
SEP 5 1913 
 
 Principles of Soil Management 
 
 BY 
 
 Dr. T. L. LYON and Professor E. O. FIPPIN 
 
 Cloth, III., i2nio, $1.75 net ; postpaid, $r.g2 
 
 The volume is a complete and comprehensive study of everything 
 relating to soils and soil management. The material is arranged 
 under three general heads of ( 1 ) the soil as a medium for root 
 development, (2) the soil as a reservoir for water, and (3) plant 
 nutrients of the soil. 
 
 " As a book indispensable to the teacher of agriculture, the intelli- 
 gent farmer and student of farming, this is recommended." — School 
 Journal. 
 
 . . . explicit and clear, and will undoubtedly prove a valuable 
 reference book for all students of soils. — Industrialist. 
 
 " Complicated questions of farm management and conservation of 
 lands are described with care, but, at the same time, with a lucidity 
 which will gain for the book an entrance into homes of many practi- 
 cal farmers." — Philadelphia North American. 
 
 " An exhaustive and carefully prepared volume." — Suburban Life. 
 
 " It is one of the best books yet produced for college work on the 
 study of soils." — School Review. 
 
 THE MACMILLAN COMPANY 
 
 Publishers 64-66 Fifth Avenue New York 
 


 
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 LIBRARY OF CONGRESS 
 
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