ii ( 1 i i Class S SQ S' Book._ Ma ^s"^ Gpight N^_ CQESRIGIIT OEPOSm SOIL ALKALI WILEY A C; R I C U L T U R A L S li R I K S SOIL ALKALI ITS ORIGIN, NATURE, AND TREATMENT BY FRANKLIN STEWART HARRIS, Ph. D. DIRECTOR AND AGRONOMIST, UTAH AGRICULTURAL EXPERIMENT STATION, AND PROFESSOR OF AGRONOMY UTAH AGRICULTURAL COLLEGE NEW YORK JOHN WILEY & SONS, Inc. London: Chapman and Hall, Ltd. 1920 COPYRIGHT • 1920 • BY FRANKLIN S. HARRIS THE PLIMPTON PRESS • NORWOOD • MASS • U • S • A ©CI.A597386 SEP -9 i^^^O To . Dr. JOHN ANDREAS WIDTSOE PIONEER-INVESTIGATOR OF ARID AGRICULTURE, TEACHER AND FRIEND, THIS BOOK IS AFFECTIONATELY DEDICATED PREFACE The study of soil alkali is by no means simple, nor have all the problems relating to it been solved. The many different salts involved, each with its own properties; the various types of soils in which these salts occur, all with different textures and composition; the complex relations between the soluble salts of the soil and the plants growing on it; and the several economic factors involved in the reclamation of alkali land: these and numerous other considerations make the problems connected with soil alkaU as difficult to solve as any found in agricultural science. The excuse for writing a book on a problem that is so far from solution is found in the great demand that exists for one volume containing the important information concerning alkali. At present, the literature of the sub- ject is very much scattered and is largely unavailable to the average student of soils. There are hundreds of millions of acres of land in the world that are at present not used for agriculture but which might become productive if the alkali could be eliminated. The need for more land to supply food for the world's increasing population is making a very insistent demand that some of these alkali lands be made available. The response to this demand will depend on a better under- standing of the nature of alkali and methods of reclaiming land impregnated with it. This accounts for the new in- terest that is being shown in the study of soil alkaU. viii PREFACE The present volume is intended as a text and reference work for students of soils and others interested in arid agriculture. It should find wide use by county agricul- tural agents and the better trained farmers in regions where the alkaU problem is encountered. References are given in connection with each chapter. The figures in parenthesis in the body of the text indicate the number of the reference at the end of the chapter. No attempt has been made to cite all the literature, but most of the important papers are included. Foreign titles have usually been translated into English in order to make them clearer to the general reader. Where the original article is Ukely to be unavailable an attempt has been made to refer to an abstract in some available publication such as the Experiment Station Record. The author wishes to acknowledge his indebtedness to all who have contributed either directly or indirectly to the work. He has drawn freely from all available sources, but he is particularly indebted to Dr. E. W. Hilgard and his associates in California and to the workers in the Bureau of Soils, U. S. Department of Agriculture. These two sources of information have proved to be veritable "gold mines." The following who have read part or all of the manu- script have given many valuable suggestions: Doctors J. E. Greaves, E. G. Peterson, F. L. West, Willard Gardner, and G. R. Hill, Jr., and Professors George Stewart, O. W. Israelsen, D. W. Pittman, M. D. Thomas, Mrs. B. C. Pittman, and Mr. K. B. Sauls. The author also wishes to express his appreciation to the several assistants and co-workers who have helped in his experiments with alkali during a number of years. Without the faithful and efficient services of these men the • PREFACE ix experimental work which led up to this book could not have been done. Mr. N. I. Butt deserves special mention for his help in reviewing literature and preparing the material of this book for publication. F. S. Harris Logan, Utah November i, 1919 CONTENTS CHAPTER PAGE I. Introductory 3 II. Geographical Distribution 6 North America. Canada. United States. Mexico. South America. Africa. Egypt. Europe. Asia. India. Australia. III. The Origen of Alkali i6 Composition of Soil-forming Materials. Salts from Ancient Seas. Jurassic Beds, Montana. Arms of the Ocean. Evapora- tion of Saline Lakes. Formation of Soluble Carbonates. Nitrate Formation. Concentration by Irrigation Water. Rela- tion of Origin to Methods of Treatment. IV. Nature of Alkali Injury to the Plant 34 Prevention of Water Absorption. Effects on Germination. Effect on Structure of the Plant. Injury at the Surface of the Soil. V. Toxic Limits of Alkali 42 Toxicity in Solution. Nutrient Solutions. Alkali Solutions. Seed Germination. Seedling Transference into Alkaline Solu- tions. Soil Results: in Sand, in Loam Soil. VI. Native Vegetation as an Indicator of Alkali 60 How Plants Indicate the Soil. Alkali-indicating Plants: Well- defined Alkali-indicating Plants, AlkaU-indicating Plants not Commonly Forming the Major Portion of Alkali-land Vegeta- tion. Discussion of Plants: Inkweed or Salt-wort, Tussock Grass {Sporobolus air aides), Kern Greasewood or Bushy Sam- phire {AUenrolJea occidcntalis) , Dwarf Samphire {Salicornia sublerminalis), Greasewood {Sarcobatus vermiculalus) , Alkali- heath {Frankcnia grandfolia campenslris), Cressa {Cressa cretica truxillensis), Salt-bush or Shadscale {Ahiplex spp.), Kochia or White Sage {Kochia vestita), Salt-grass {Distichlis spicata), Other Plants. Description of Alkali-indicating Plants. xi xii CONTENTS CHAPTER PAGE VII. Chemical Methods of Determining Alkali 8i Preparing the Solution: from Moist Soil, from Dry Soil. De- termining Total Solids. Carbonate and Bicarbonate Determina- tion. Chloride Determination. Sulphate Determination. Nitrate Determination. Analytical Process. Determination of Bases: Calcium, Magnesium, Sodium. Other Methods of Determining Soluble Salts: the Electrical Bridge, Freezing-point Method, Biological Method. VIII. Chemical Equilibrium and Antagonism , 105 Solubility of Alkali Salts. Mass Action. Absorption of Salts by Soils. Equilibrium in Soil Solution. Antagonism between Alkali Salts. IX. Relation of Alkali to Physical Conditions in the Soil. ... 119 Changing Soil Structure. Effect of Colloids. Hardpan. Effect on Moisture Movements. Evaporation of Moisture. X. Relation of Alkali to Biological Conditions in the Soil . 132 Relation of Soil Organisms to Fertility. Biological Inactivity and Soil Sterility. Concentrations of Alkali which Limit Biolog- ical Activities. XI. Movement of Soluble Salts through the Soil 141 Salts in Natural Soils. Salt Movement with Water. Effect of Water-table. Movement of Various Salts. Rate of Alkali Movement. XII. Methods of Reclaimlng Alkali Lands 154 The Source of Contamination. Reducing Evaporation. Plowing under of Surface Alkali. Removing from Surface. Neutralizing Sodium Carbonate. Other Chemical Treatments. Cropping with Alkali-resistant Crops. Drainage. XIII. Practical Drainage 167 Advantages of Drainage. Determining the Need of Drainage. Types of Drains. Cement Tile for Alkali Land: Preliminary Survey, Laying out the System, Size of Drains, Construction Methods. Outlets and Silt Basins. Cost of Drainage. XIV. Crops for Alkali Land 192 Factors Affecting Resistance. Economic Factors Affecting Choice. Tolerance of Alkali by Various Crops; Forage Crops, CONTENTS xiii CHAPTER PAGE XIV {continued) Alfalfa, Sweet Clover {Mcliloliis alba and M. officinalis). Other Clovers: Vetch {Vicia saliva and V. villosa), Field Peas {Pisum sativum), Beans. Grasses: Timothy, Orchard Grass {Daclylis glom-erata), Brome Grass {Bromus incrmis), Red Top {Agnostis alba), Blueg ass {Poa pralensis), Western Wheat Grass {Agropy- ron), Japanese Wheat Grass {Agropyroii J aponicum) , Rye Grass, Fescue, Tall Meadow Oat-grass {Arrhcnatherum elatins), Wild or Native Grasses, Salt Grass {Distichlis spicala), Bluestem Grass {Agropyron Occidenlale), Tussock Grass or Purple Top {Sporo- bolus airoides). Alkali Meadow Grass {Puccinellia airoides), Prairie Grasses, Modiola {Modiola procumbens). Salt Bushes {A triplex spp.). Giant Rye Grass {Elymus condensatus) , Sedges and Rushes, Millets, Sorghums, Rape {Brass ica napus and B. oleracea). Grain Crops: Wheat, Barley, Oats, Rye, Corn, Rice, Emmer, Sunflowers. Root and Vegetable Crops: Sugar-beets, Potatoes, Onions, Asparagus, Celery, Radishes, other Vegetables. Fiber Crops: Flax, Cotton. Trees and Shrubs: Fruit Trees and Shrubs, Date Palms, Grapes, Olives, Other Fruits, Other Trees. XV. Alkali Water for Irrigation 224 Sources of Contamination. Observed Toxic Limits. Compo- sition of Typical Alkali Waters. Factors Modifying Toxic Limits of Salt. XVL Judging Alkali Land 240 Geology of Region. General Appearance. Native Vegetation. The Water-table. Analysis of the Soil. Possibility of Reclama- tion. Economic Factors. Index 247 LIST OF ILLUSTRATIONS VIC. PAGE Wheat Raised on Reclaimed Alkali Land Frontispiece 1. Salt-bearing Shale Formation 24 2. Mancos Shale Hill 26 3. Normal and Plasmolyzed Cells 35 4. An Orchard Planted on Land that Came from a Formation High in Soluble Salts % . . . . 37 5. The Lower Part of an Orchard being Killed by Alkali brought to the Surface by a Rising Water Table. . 39 6. Experiments to Determine the Toxicity of Various Alkali Salts 50 7. Growth of Wheat with Various Concentrations of Different Salts 54 8. Alkali Crusts at the Surface Preventing the Growth of Practically all Vegetation 61 9. Alkali Land which is Indicated by the Growth of Shadscale 62 10. Greasewood and Shadscale 66 11. The Border between Greasewood and Salt Grass. ... 68 12. The Last Plant to Abandon an Alkah Flat 71 13. Plants Growing at the Top of Sand Dunes 74 14. Determining Soluble Salts with the Electric Bridge in the Field 102 15. Alkali Coming to the Surface where Seepage Water from a Canal Comes to the Surface and Evaporates no XV xvi ILLUSTRATIONS i6. Black Alkali Crust Forming where the Land has been Wet 115 17. Cultivated Land that had to be Abandoned because of the Rise of Alkali 143 18. Alkali Eating away the Fence Posts 147 19. Typical Hard Pan Found in Arid Soils 156 20. Field Ready for Laying Tile 16S 21. Boggy Alkali Land that is Difficult to Drain with Short Tile 171 22. Open Ditch used to Carry away the Drainage Water from a Large Area 172 23. Machine for Making Drains in Heavy Soil without the Use of Tile 173 24. Poorly Made Cement that is being Crumbled by Alkali 175 25. Method of Establishing Grade of Drains 177 26. Types of Lumber Drains used to Reclaim Boggy Alkali Land 180 27. Wood Drains being used to Drain Boggy Alkali Land 184 28. Drainage Machine with Digging Wheel above the Ground 186 29. Drainage Machine with Digging Wheel in the Trench 187 30. Silt Box with Lid. The Silt that Settles in the Box can be Spaded Out 189 31. Alkali Spot in a Grain Field 211 32. The More Tender Trees are being Killed with Rising Alkali, while Alfalfa is Still Unaffected 227 33. Layer of Alkali Several Feet below the Surface 241 SOIL ALKALI SOIL ALKALI CHAPTER I INTRODUCTORY Whenever the word "alkali " is mentioned there im- mediately arises in the minds of some people a vision of desolation. They may picture to themselves a barren tract of land devoid of vegetation and covered with a blanket of white salt mixed with earth; or they may fancy that they see worthless wastes of what had been fertile helds. They imagine beautiful trees being reduced to stumps and fence posts and remnants of farm buildings gradually being eaten away by a slowly advancing white cover, which will eventually reduce the entire landscape to a gray barrenness. Probably each of these pictures has a prototype in some local section. Alkali does prevent the cultivation of vast areas of land, and it has caused the abandonment of many fertile fields; but to give up all effort when alkah makes its appearance would be like abandoning a farm just because some crop became in- fested with a pest. The successful pursuit of agriculture calls for the con- stant overcoming of difficulties. New problems arise each season, but success demands that these be solved. The difference between civilization and savagery consists largely in meeting difficulties and being masters of nature instead of merely victims of circumstance. 3 4 INTRODUCTORY The welfare of the entire people is dependent on the prosperity of agriculture, and in turn agriculture rests on the productivity of the soil. Human well-being is therefore closely tied up with the land. Whatever affects agricul- ture is important not only to the tillers of the soil but to all who consume the products of the farm. In order that an ample food-supply may be assured at a low price, the people generally are interested in having available as large a producing area as possible. Most of the more desirable lands of the world have been settled. This means that an extension of the area of pro- duction will often necessitate the use of land that has some unfavorable condition. There are in the world vast tracts that are not susceptible of cultivation without special treatment. In the arid parts of the earth, which comprise about one-half of the total land, two great conditions are withholding from cultivation millions of acres of land. They are drouth and alkali. The successful overcoming of drouth and alkali means the addition of countless acres to the productive part of the earth. It is with alkali and its conquest that the present volume deals. It has been estimated that about 13 per cent of the irrigated land of the United States contains sufficient alkali to be harmful. This means that there are over nine million acres of land under present canal systems that are affected with alkali. There are many more million acres of alkali land in the United States that do not lie under irrigation systems. Similar figures might also be given for other countries of this continent and for all of the other continents. The alkali problem is one of no mean importance to farmers, nor to any who are interested in the world's food-supply. In a strictly chemical sense the word "alkali " refers INTRODUCTORY 5 to a substance having a basic reaction. As applied to the soil, however, this restricted meaning does not hold, and alkali refers to any soluble salts that make the soil solution sufficiently concentrated to injure plants. This includes the chlorides, sulphates, carbonates, and nitrates of sodium, potassium, and magnesium, and the chloride and nitrate of calcium. The sulphate and carbonate of calcium are not sufficiently soluble to be injurious to crops. Most of the alkalies are in reality neutral salts. It may be some- what unfortunate to use for general substances a word that also has a restricted technical meaning, but the word has become so well established in agricultural literature that it would now be very difficult to change it. Aside from their practical importance, the soluble salts of the soil are of great scientific interest. They offer fruitful fields for investigation to the geologist, the chemist, t^e plant physiologist, the bacteriologist, the mycologist, the agronomist, and the engineer. The complexity of the soil makes the problems connected with alkali very difficult to solve. There are so many interacting factors that no simple statement of the problem can be made and no simple solution arrived at. A complete under- standing of the problem will call for careful researches by investigators in different branches of science and a careful coordination of the findings. The importance of the subject justifies giving it the' most careful consideration. CHAPTER II GEOGRAPHICAL DISTRIBUTION Soils containing injurious quantities of alkali are found on every continent. These soils, however, do not occur in all parts of the continents, the distribution being con- fined to areas where conditions favorable to their formation prevail. The most important of these conditions is aridity. Another important factor is the nature of the rock from which the soils were formed. Because these conditions are local, alkaH soils are likely to be found over large areas, but all the soils of these areas are not necessarily highly charged with soluble salts. Part of the soils in a region having a climate favorable to alkali formation may be derived from rocks that are low in soluble salts and may have been so deposited that they have good natural drain- age. Soils of this kind do not contain alkali even though most of the soils of the region are impregnated. Likewise, soils high in soluble salts may be found over limited areas in regions where most of the soils are free. This condition is sometimes found in climates that are not entirely arid, or where a soil having poor drainage was derived from rock that was high in soluble salts. Thus, the alkali problem has local as well as general aspects. A general alkali condition may prevail over an extensive region, the smaller areas of which may be exceedingly variable. North America. — More than half of the North- Ameri- can continent is arid or semi-arid. Throughout this vast area alkali soils are found. There are many large tracts 6 CANADA 7 in which the soluble salt content of the soil is not at present sufficient to interfere with crop growth, but there is suffi- cient of the salts present if concentrated by unwise methods of irrigation, by drouth, or by other means to bring the soil to the danger point, especially should drainage be poor. The looth meridian may be taken roughly as the line separating the humid from the arid part of the continent. This Hne is not absolute; it varies somewhat with latitude, altitude, and several other factors. There are a number of places west of this line where the rainfall is high. This is i)articularly true along the northwest coast and along some of the mountain ranges. Canada. — In western Canada, especially in the prov- inces of Saskatchewan, Alberta, and British Columbia, there are several rather large tracts where the soluble- salt content of the soil is sufficiently high to render crop production difficult. In southeastern Alberta the soil of one of these regions originated from the glaciation of shale that was high in soluble salts, particularly the sulphates. Therefore, sulphates are the predominating salt of the region. The soil is heavy^ and impervious; consequently, there has been very little movement of salts from its original place in the soils. Under irrigation these salts may be either leached down- ward or brought to the surface. When appearing as a white inflorescence they are very conspicuous and would lead the casual observer to believe the condition to be much worse than it really is. A large quantity of gypsum is present in these soils and, when dissolved and brought to the surface, it, together with sodium sulphate, forms a conspicuous white soil covering. Fortunately, the percentage of the more harmful chlorides and carbonates is verv low. 8 GEOGRAPHICAL DISTRII^UTION The composition of an alkali soil in Alberta as determined by Shutt (i6) is given in the following table. Table I. Soluble Salts in Alkali Soil of Alberta, Canada (Per Cent) Depth (feet) Growth Na2S04 MgSOi CaS04 Total Soluble- saline Content 0.0-0.5 0.5-1-5 Good .178 .087 .163 .440 I- 5-30 .877 ■132 ■447 1572 3 0-5.0 •973 .563 2.926 4.640 30-S.O Poor .123 .180 .701 .247 .491 1.480 .719 •309 .588 1.680 •799 .062 .192 1.060 30-5. No 1. 741 .goo .648 3.260 1 .001 323 •364 1.700 .701 .222 .220 1. 164 •579 .084 .192 .900 United States. — In sixteen or seventeen of the western states of the Union, alkali is found to be one of the chief agricultural problems. The problem is much more acute in some regions than others. The San Joaquin, Sacra- mento, and Imperial Valleys of California; the Great Basin, comprising a large part of Utah and Nevada; the Colorado River drainage basin, comprising parts of Wyoming, Utah, Colorado, Arizona, and California; the Rio Grande River drainage area, including parts of New Mexico and Texas; parts of the Columbia River drainage basin ; and rather extensive sections in the Great Plains east of the Rocky Mountains include the most important parts of the United States affected with alkali. In practically all the western states certain areas affected by alkali have been described in publications of the state MEXICO experiment stations or in the United States Bureau of Soils. (See Table II.) These publications show that the composition of the alkali salts as well as the methods of reclamation vary greatly. Table II. Composition of Alkali from Different Parts of THE United States Expressed in Percentage of Different Salts Percentage of Different Salts in the Alkali Salts Colorado! California- VVashing- toii' Montana' Arizona^- Crust Surface, 10 in. Crust 0-72 in. KCl K2SO4 K2CO3 NaoS04 NaN03 NasCOs NaCl Na3HP04 MgS04 MgCl2 CaCl2 NaHCOs CaS04 Ca(HC03)2. . . . Mg(HC03)2. . . (NH4)2C03.... 1 .64 33-07 6.61 12.71 17.29 21.48 3-95 25^28. 19-78 32-58 14-75 2.25 1. 41 5.61 9 73 13-86 36.72 1.87 16.48 15-73 I .60 85-57 0-55 8.90 0.67 2.71 21.41 35-12 ■7^28 4.06 22.06 10.07 4.00 81.15 7.71 0.25 0.28 6.61 22.10 13-77 6!88 3-98 21.02 32.25 Mexico. — The greater part of the high plateau of Mexico has an arid climate. This, like all similar regions, has had but comparatively little of the soluble salts contained in the country rock removed. In this section there are many large valleys having no outlets. During ' Colorado E.xp. Sta., Bui. 155, p. 10. ^ Hilgard "Soils," p. 442. ' U. S. D. A. Bur. Soils, Bui. 35, p. 79. ^ U. S. D. A. Bur. Soils, Bui. 35, p. 103. 6 U. S. D. A. Bur. Soils, Bui. 35, p. 109. 10 GEOGRAPHICAL DISTRIBUTION the rainy season the lower parts of these valleys are flooded by the waters of swollen streams; during the dry season this water is practically all evaporated, leaving its soluble material behind. This results in great level bodies of land charged in varying degrees with soluble salts. The composition of these saline deposits depends on the com- position of the country rock through which the streams flow. Very little work up to the present time has been done to reclaim the alkah soils of Mexico. South America. — No important published material is available on the alkah condition of the soils of South America. It is known, however, that the arid sections of that continent do not differ essentially from those of other arid sections of the world. Practically the entire western part of the continent is arid and throughout this section areas subject to alkah troubles are found. It includes most of the Pacific slope west of the Andes and the greater part of the western plains of Brazil and Argentina east of these mountains. The deposits of sodium nitrate in Chile are a conspicuous example of the retention of soluble salts that would be leached out in a humid chmate. Africa. — The distribution of alkali soils in Africa is not the same as in North and South America. It is found over practically the entire northern portion of the con- tinent and also in the southwestern part. The central, and particularly the west-central, portion is practically free. Throughout the Union of South Africa up into Rhodesia alkali soils are found but have not received as much attention as some of the sections of North Africa, particularly in Egypt. The soils of the Sahara as well as many of those of Algeria, Morocco, and Tunis are so contaminated with soluble salts that it was necessary for EGYPT 1 1 the agriculture of these countries to be adjusted to this condition. It is probable that the alkah problem is being given more consideration in Egypt than elsewhere. Egjrpt.- — The greater part of Egypt is a barren desert, being one of the most desolate parts of the earth. The an- nual precipitation at Alexandria averages 8.26 inches; at Port Said, 3.49 inches; and at Cairo it is only 1.06 inches, which is not enough to support vegetation of any kind. The country is traversed from south to north by the Nile River along which is a narrow, highly cultivated, and thickly populated strip of river-formed land. In the southern part of the country the river flows through sand- stone and occupies a shallow valley, but farther north a deep gorge is cut down from the surrounding limestone plateau. On both sides of the river are alluvial plains composed of fine silt which for the most part has been carried by the Nile from the disintegrated volcanic material of the Abyssinian highlands. Thus the soil of the lower Nile Valley bears no relation to the country rock of the immediate vicinity. In the delta portion of the valley, the land is very flat and there is but little opportunity for drainage. Much land that was cultivated anciently has since been abandoned on account of the accumulation of alkah. The area thus abandoned has been estimated to be more than one and a half million acres. Most of this land is on the fringe that borders the sea and is influenced by sea water. The higher lands are practically free from alkah. Formerly all the land was watered by the basin system of irrigation. With this method, the land is flooded to a depth of from three to five feet at the season when the Nile is high. After standingat this depth for al)out six weeks and allowing the sediment to settle, the water is drained 12 GEOGRAPHICAL DISTRIBUTION back into the Nile, and the crops are planted in the mud without plowing. By this system only one crop is grown each year, but the accumulation of alkali is prevented by washing part of it to lower depths in the soil, by depositing a fresh layer of salt-free silt on the surface, and by carrying away with the water that is drained off any soluble material that may have accumulated on the surface at the time of flooding. In order to raise more than one crop a year and thereby get greater profit from the land, the basin system of irri- gation is being largely supplanted by the perennial system, by means of which water is applied throughout the year. This brings about almost continuous evaporation from the surface and a consequent accumulation of soluble salts. Of the 6,250,000 acres of irrigable land in Egypt, only about 1,730,000 acres are irrigated by the old system of basin irrigation. This means that the alkali problem will continue to be more acute in Egypt until suitable means of coping with it are worked out. Already some rather ingenious methods (23, 25) of drainage are in operation. The following analysis reported by Means (14) of an alkali soil from Kom-el-Akhdar is typical of the alkali land of lower Egypt: Table III. Chemical Analysis of Alkali Soil from Kom-el- Akhdar, Egypt (Surface foot) Ions Per cent Conventional Combinations Percent Calcium (Ca) Magnesium (Mg) Sodium (Na) Potassium (K) Sulphuric Acid (SO4) .... Chlorine (CI) Bicarbonate Acid (HCO3) 307 2.00 28,83 1 .90 24.56 38.62 1 .02 Calcium Sulphate (CaSO^). . . . Magnesium Sulphate (MgS04) Potassium Chloride (KCl) .... Sodium Chloride (NaCl) Sodium Bicarbonate (NaHCOs) Sodium Sulphate (Na2S04) .... Per cent Soluble 10.43 9.90 3.62 60.88 1. 41 1376 8.2 INDIA 13 Europe. — Of all the continents, Europe is the most free from alkali, although it has several alkali sections. Probably the most conspicuous of these is found in Hun- gary. The "Szik " lands of the plains contain some soluble salts and lower down in the valley of the Theiss genuine alkali lands are found with a high content of both white and black alkali. From these lands carbonate of soda has long been obtained commercially. In the lower valley of the Po in Italy (2) and in many other sections of Europe bordering the Mediterranean local alkali areas are found. Asia. — The main alkali regions of Asia are found in the central and southwestern portions of the continent. Arabia, Mesopotamia, Persia, Afghanistan, Baluchistan, Turkestan, and Northern India are all more or less affected with alkali salts. In some of these countries agriculture has continued in spite of the excess of soluble salts because special methods have been devised as a result of experience extending back to prehistoric times. Modern investigations of alkali have been more complete in India than in other parts of Asia; consequently, more attention will be given to that country in the present discussion. India. — The alkali, or reh, lands of India were first investigated by the "Reh Commission " about 1876. This commission was appointed to discover the cause of deterioration of some of the lands that had previously been fertile. Since that time the various experiment stations in India have made more extensive investigations. They have shown that "usar" lands (12) exist largely not only in the northwestern provinces and Oudh, but also in the Punjab, especially on lands bordering the Chenab River, likewise to a slight extent in the Bombay Presidency. 14 GEOGRAPHICAL DISTRIBUTION The Reh Commission brought out the fact that under the ancient systems of agriculture in India there was very httle increase in the amount of soluble salts at the surface, but with the construction of large modern canals and the appHcation of unnecessarily large quantities of irrigation water the increase in alkali was very rapid. Leather (12) has pointed out that not all the lands called by the natives "usar " owe their infertility to alkali. Some simply have very hard clay soils which are difhcult to bring into a good state of tilth. The true "reh" lands, however, are like the alkah lands of other parts of the world. Australia. — The greater part of Australia may be con- sidered as arid although the rainfall of the eastern part of the continent is high. During the last generation large irrigation works have been constructed and vast tracts of land containing a rather high content of soluble salts have been brought under cultivation. In such sections alkali is one of the serious problems. Alkah conditions in Aus- tralia are somewhat similar to those of the western part of the United States. REFERENCES 1. Ames, J. W. Some Alkali Soils in Ohio. Ohio Sta. Mo. Bill, i (1916), No. 7, pp. 209-210. 2. Atti, R. a Saline Soil of the Lower Valley of the Po (Italy). Accad. Econ. Agr. Firenze, 5, Ser. 3 (1906), No. i, pp. 59-64. (Abs. E. S. • R. 18, p. 215.) 3. Bancroft, R. L. The Alkali Soils of Iowa. Iowa Sta. Bui. 177 (1918), pp. 185, 208. 4. BuRD, J. S. Alkali Conditions in the Payette Valley. Idaho Sta. Bui. 51 (1905), pp. 1-20. 5. Clarke, F. W. The Data of Geochemistry. U. S. Geol. Survey, Bui. 616 (1916), pp. 143-167 and 206-247. 6. Deakin, Alfred. Irrigated India, 322 pp. (London, 1893.) REFERENCES 15 7. DiMO, N. A. Innuciuc of Irrigation and of Increased Natural IIu- midily on tlic Process of Salt I-ormation and of tlie 'rrans[)ortation of Salts in the Soils and Subsoils of Ciolodnoi (Ilunj^ary) Stcjipe, Smarkand Province. Kuss. Jour. iCxj). Landw. 15 (1914), No. 2, PP- 336-338. (Abs. K. S. R. 34, p. 16.) 8. Hebert, a. Alkali Soils from the Knee of the Niger River. Hul. Soc. Chim., France, 4, Ser. 9 (191 1), Nos. 16, 17, pp. 842-843. 9. HiLGARD, E. W. Soils, pp. 423-424. (New York, 1906.) 10. Hill, E. G. The Analysis of Rch, the Alkali Salts in Indian Usar Land. Proc. Chem. Soc, London, 19 (1903), No. 262, pp. 58-61. (Abs. E. S. R. 14, p. 1056.) 11. Ke.arney, T. H., and Means, T. H. Crops Used in the Reclamation of Alkali Lands in Egypt. U. S. D. A. Yearbook (1902), pp. 573-588. 12. Leather, J. VV. Investigation of Usar Land in the United Provinces, Allahabad, India. Govt., 1914, pp. 88. (E. S. R. ^:i, p. 419.) 13. Mann, H. H., and Tamhaxe, \^ .\. The Salt Lands of the Nira Valley (India). Dept. of Agr., Bombay, Bui. 39, 35 pp. 14. Means, T. H. Reclamation of Alkali Lands in Egypt. U. S. D. A. Bur. of Soils, Bui. 21 (1903), 48 pp. 15. MacOwan, p. Black Land in Relation to Irrigation and Drainage, .Agr. Jour. Cape Good Hope, 23 (1903), No. 5, pp. 573-581. 16. Shutt, E. T. and Smith, E. A. The Alkali Content of Soils as Related to Crop Growth. Trans. Roy. Soc. Can. Ser. 3 (1918), Vol. 12, pp. 83-97. 17. SiGMOND, A. VON. On the Types of "Szik" Soils of the Hungarian .■\lfold. Eoldtani Kozlony, 36 (1906), No. 10-12, pp. 439-454. (.Abs. E. S. R. 19, p. 1117.) 18. Snow. F. J., Hilgard. E. W.,and Shaw, G. W. Lands of the Colorado Delta in the Salton Basin. Cal. Sta. Bui. 140 (1902), pp. 51. 19. Stevenson, W. H., and Brown, P. E. Improving Iowa's Peat and Alkali Soils. Iowa Sta. Bui. 157 (1915), pp. 45-79. 20. Traphagen, F. W. The Alkali Soils of Montana. Mont. Sta. Bui. 18 (1898). pp. 50. 21. Tulaikov, N. Soils of the Kirghiz Steppe. Russ. Jour. Exp. Landw. 9 (1908), pp. 628-630. (Abs. E. S. R. 22, p. 617.) 22. VissoTSKi, G. The Soil Zones of European Russia in Connection with the Salt Content of the Subsoils and with the Character of the Forest Vegetation. Pochvovedenie (Pedologie), i (1899), pp. 19-26. (Abs. E. S. R. 12, p. 925.) 23. WiLLCOCKS, W. Egy[)tian Irrigation, 485 pp. (London and New York, 1899.) 24. WiLLCOCKS, \V. The Irrigation of Mesopotamia. (London and New York, 191 1.) 25. WiLLCOCKS, W. The Nile in 1904, 225 pp. (London, 1904.) CHAPTER III THE ORIGIN OF ALKALI The presence of alkali incrustations over the surface of the soil was observed long before scientists were able to account for the origin of these salts. This led to quite a number of theories regarding the source of the alkali. Several of the early theories have been found untenable in the light of later investigation. Many of the formerly obscure facts are now definitely known and there is a much clearer idea of the source of the soluble salts of the soil; but even today considerable difference of opinion exists regarding the origin of some of these salts. More data must be gathered before it will be possible to state definitely why certain deposits of alkali occupy their present position and maintain their present composition. It is definitely known that there are a number of distinct conditions promoting the accumulations of alkali in various sections. Table IV. Average Composition of Igneous Rocks, Shale, AND Sandstone (Per Cent) Quartz Feldspar Hornblende and pyroxene. Mica Clay Limonite Carbonates Other minerals Igneous Rocks 12. 59 i6 3 Shale 22.3 30.0 Sandstone 66.8 ii-S 6^6 1.8 li.i 2.2 16 COMPOSITION OF SOIL-FORMING MATERIALS 17 Composition of Soil-forming Materials. There seems to be no doubt that the soluble salts of the soils have come from the same materials as the soils. The exact chemical reactions that have brought about these changes and the methods of concentrating the soluble constituents are, however, not so well known. The materials composing the soil have been derived largely from the rocks and minerals which constitute the crust of the earth, together with a greater or lesser quantity of organic matter coming from the dead bod ies of plants. Table V. Average Composition of the Lithosphere Ipneous (95 per cent) Shale (4 per cent) Sandstone (0.75 per cent) Limestone (0.2s per cent) Weighted Average SiOs AI2O3 FeoOa FeO MgO CaO NajO K2O H2O TiOz ZrOa CO2 P2O5 S SO3 59 14 2 3 3 4 3 2 I 83 98 65 46 81 84 36 99 89 78 02 48 29 II 58.10 IS 40 4.02 2^45 2.44 3-II 1.30 3^24 5.00 .65 2.63 •17 ■"■.64 •OS "'^So 78.33 4-77 1.07 •30 1. 16 5-50 •45 131 1.63 •25 5^03 .c8 .07 •05 5^19 .81 •54 "7'89 42.57 •OS ■33 •77 .06 41 54 .04 •09 •OS .02 •05 59 14 2 3 3 4 3 2 2 77 89 69 39 74 86 25 98 02 77 02 70 28 10 03 06 09 09 04 09 025 OS 025 01 CI F BaO SrO MnO NiO CrsOs V2O3 LiiO C 06 10 10 04 10 025 05 02s 01 100.000 100.00 100.00 100.00 100.000 18 THE ORIGIN OF ALKALI Compilations made by Clarke (6) show the earth's crust to be made up largely of the important minerals shown in Table IV (page i6). On the basis of the composition and relative amount of the different rocks he computes the average composition of the earth's crust as shown in Table V (page 17), Clarke (6) gives the composition of the ocean waters as follows: Table VI. Composition of Ocean Water Salts Per cent Elements Per cent Sodium Chloride (NaCl) 77.76 Oxygen 85 79 Magnesium Chloride (MgCl.;) . . . ID 88 Hydrogen. . . . 10 67 Magnesium Sulphate (MgS04). . 4 74 Chlorine 2 07 Calcium Sulphate (CaS04) 3 60 Sodium I 14 Potassium Sulphate (K2SO4) • • . . 2 46 Magnesium . . . 14 Magnesium Bromide (MgEr^) . . . 22 Calcium 0^ Calcium Carbonate (CaCOs) ... ^4 Potassium. . . . 04 Sulphur oq Bromine 008 Carbon 002 100 . 00 100.00 He reports a maximum saUnity of 37.37 grams of salts to a kilogram of water, or 3.737 per cent with an average of about 3.5 per cent. These figures give a general idea of the materials from which soils are made and the substances which have been leached from them. In order to determine soluble matter that might be washed from rocks and minerals of various kinds, Whitney and Means (23) compiled the material contained in Table VII from the writings of G. P. Merrill. This table gives an idea of the material that is usually washed from rocks and minerals of different kinds in the COMPOSITION OF SOIL-FORMING MATERIALS 19 Taiu.k VII. y\M<)UNT OF Soluble Matter Removed in the Decomposition of Rocks and the Formation of Soils Rock Removed by Solu- tion FROM Each Acre- foot OF Soil Formed Kind of Rock Locality Per cent Tons (iranito District of Colunihia i,^ 26r (Jiieiss Virj^inia 45 1,431 Syenite Arkansas 5" 2,227 ]*henolite Bohemia ID 1 95 Diabase Massachusetts 15 309 Diabase Venezuela 40 1,166 Basalt Bohemia 44 1,376 Basalt France 60 2,625 Diorite Virginia 38 1,072 Soapstone Maryland 52 1,89s Soapstone Virginia 78 6,204 Limestone Arkansas 98 85,760 formation of soils. Dissolved material may be washed to the sea or into lakes, or it may simply be transferred to lower lying soil and there often concentrated so highly that it becomes injurious to plant growth. Some of these dissolved materials, such as limestone, are not sufficiently soluble to be troublesome even in the highest possible concentrations. Table MIL Percentage of Alkalies in Various Soil- forming Minerals Feldspars Per cent of Alkalies Micas Per cent of Alkalies Orthoclase 17 17 12 Q 8 4 35 2 Muscovite Biotite Phlogopite Nepheline Leucite 12 Microline Albite Olioclase Andesite. . . 10 9 24 21 . =; Labradonte Sodalite Haiiyne 26 Bytownite 17 Anorthite 20 THE ORIGIN OF ALKALI The same authors (23) give a list of alkaH-bearing min- erals occurring in primary rocks as the ultimate source of soil alkah. "Some of these alkali-bearing minerals are very generally present in the primary rocks from which the soils have all ultimately been derived, but they are of course usually mixed with other minerals, so that the total percentage of alkaHes in the rock is not so great as would appear from these minerals." As to the method of separating these soluble substances and transferring them to the surface, Cameron suggested a hypothesis which is quoted by Dorsey (7) as follows: "The major part of the complex crystalline masses or of rocks forming the earth's crust contain chlorine and sulphur. F. W. Clarke gives as an average 0.07 per cent chlorine and 0.108 per cent sulphur. As a result of the hydrolyzing action of water and other decomposing agencies probably all the chlorine and very much of the sulphur is converted into hydrochloric acid and sulphuric acid, which in turn form the corresponding salts of the alkalies and alkaHne earths. The aggregate amount which is thus being constantly formed in the subsoils and under- lying strata of any one area must be very large. As evaporation proceeds at or in the surface soil, there Is a rise of the water in the underlying layers through the capillary spaces toward the surface, bringing with it the hydrochloric and sulphuric acids or their salts. "The sulphuric acid moves up more slowly than does the hydrochloric acid; partly, perhaps, because the rock masses and the soils have a greater absorbing action on sulphuric than on hydrochloric acid, tending to withdraw it from solution; partly, perhaps, because reducing con- ditions may exist on some layers tending to the formation COMPOSITION OF SOIL FORMING MATERIALS 21 of metallic sulphides; and, partly, undoubtedly, to the formation of the slightly soluble calcium sulphate. This last, however, is gradually brought toward the surface, and is often found in enormous masses at moderate depths in the soils of arid regions. Undoubtedly the calcium carbonate so generally found in large masses at moderate depths in the soil of arid regions originates in a similar manner. "Hydrochloric acid is transported through soils and most absorbing media with comparative ease. Moreover the chlorides of the alkalies and alkaline earths are readily soluble. Chlorides should be expected, therefore, to accumulate in preponderant masses at the surface, which under arid and semi-arid conditions they generally do. "The preponderance of sodium chloride above other chlorides is readily expHcable. It is well known that when solutions of chlorides are poured through columns of soil or similar substances, offering a large surface of contact to the solution, there is a well-marked selective absorption, the soil tending to withdraw the base from the solution to a decidedly greater extent than the acid, with the result that the leaching generally contains free acid. So far as the experience we have goes, it would seem that, in general, soils absorb potassium most readily, then magnesium, calcium, and sodium in the order named. Supposing the hydrochloric acid when found in the lower layers to be neutrahzed with a mixture of these bases, as it rises in the capillary movement, there is always a tendency, owing to the selective absorption of the soil, toward a lagging behind of the potassium, a lesser lagging of the magnesium and calcium (these bases probably tending also to form the much less soluble sulphates and carbonates) and a much less lagging of the sodium. In consequence, sodium 22 THE ORIGIN OF ALKALI is the predominating base in the readily soluble salts at the surface." This hypothesis does not explain the method of accumu- lation of alkali at certain places in the soil; it merely attempts to show why certain salts are present at the sur- face in larger quantities than others. Salts from Ancient Seas. — The observation that alkali is found in large quantities in one section, whereas it may be almost entirely lacking in another section of sim- ilar climatic conditions early led to an attempt to trace the salt to the rock from which the soil was formed. Traphagen (21), at the suggestion of W. H. Weed of the U. S. Geological Survey, made a comparison of the composi- tion of the alkali near BilKngs, Montana, with the soluble salts in the Fort Benton shales from which the soils were in part derived. As a result of this study he was led to the conclusion that in this case the soluble salts in the soil resulted from a transference of the salts to the soil while the shale was being disintegrated. This theory was afterward supported by the work of Whitney and Means (23) in the same region. Cameron (4) also mentions shale and similar deposits as a source of alkalies. It seems, however, to have been left for Stewart, Peter- son, and Greaves (17, 16, 19, 18) to explain clearly the intimate relation existing between present alkali accu- mulations and the presence of large quantities of alkali salts in country rocks from which these soils were formed. They made extensive examinations of the geological formations in Utah, Colorado, Arizona, Wyoming, Idaho, and Nevada, and analyzed the soil-forming country rock of these areas. These examinations and analyses revealed the fact that in these sections wherever alkali is present in very large JURASSIC BEDS 2.^ quantities it apparently originated from materials de- posited from concentrated solutions in some ancient sea. The deposits in the areas studied were made during Cre- taceous and Tertiary times which seemed to have been influenced by arid cHmatic conditions. This area in- cluding the eastern part of Utah, the western half of Colorado, and the southwestern part of Wyoming was covered with water during upper Cretaceous times leaving the Uintah antichne as an island. A description of the method of formation of these shales and sandstones that are so high in soluble salts is given as follows (17) : " Jurassic Beds. The Jurassic beds contain highly colored red, yellow, gray, green, or blue shale and sand- stone ranging from line grain to coarse grits. In the upper members of the deposit are often found thin lenses of limestone and an accumulation of gypsum. The ac- cumulation and position of the gypsum beds would seem to indicate that they had resulted from precipitation from the water of isolated brackish lakes. "At the end of Jurassic times the inland sea, in which the Jurassic deposit accumulated, disappeared and the area was subjected to erosion. This probably took place during lower Cretaceous times. Later the section was again covered with an inland sea and deposits were laid down unconformably on top of the Jurassic. ''These belong to the Dakota beds, the lower part of which were composed of conglomeifates and coarse sand- stones, above which are carbonaceous shales and some low- grade coal, overlain by more sandstone and highly colored shales. Above the shale are found thick beds of light- colored sandstone, shales, and dark-brown sandstones. "At about the end of the Dakota period there seems to 24 THE ORIGIN OF ALKALI have been some shifting and readjusting of the land as the Dakota beds are found to be quite thick in the northern section where the Mancos are thin; while in the southern section the Mancos are found to be exceedingly thick in places where the Dakota is comparatively thin. "Where they are not capped with the sandstone the beds do not form abrupt ledges, but weather off into rather rounded symmetrical clay hills — at least they appear Fig. I. — Salt-bearing Shale Formatiun. This Type of Soil- ' FORMING Material is a Common Source of Alkali. to be clay hills. This disintegration of the shales gives rise to a very sticky, plastic clay which forms numerous cracks when dry, but becomes a continuous coat of plastic clay when wet. The material is so close grained that when rain falls upon it, it seals up all the pores and cracks so that water does not seem to penetrate it. These hills are very sparsely covered with vegetation and it is not an unusual thing to see an area of more than an acre which does not contain a single plant. "On these rounded clay hills one seldom has to dig more than a foot before the shale is found in place. However, the material covered is not uniform, especially on top of the clay knolls. The usual condition is that on the surface is from one to two inches of earthy clay, under which is MONTANA 25 from one to six inches of what appears to be a gray ashy material. On close examination this proxies to be crystals of salt together with flocculent clay. Immediately under this is found the shale in place. Samples of the clay and gray ashy material, and the shale in place were taken separately, and the analyses show the nitrate contents of each. "The dark-colored shales show numerous crystals of g>psum in the cracks and bedding planes. Where the shale is dry and considerably weathered the gypsum appears Hke white flour. In the seams of the shale, but a foot or more under the surface in the same place, the crystals are still firm and solid. "At Emery, Utah, the gypsum crystals were not only taken out of the bedding plane of the thick layers, but numerous cross fractures WTre found which were also filled with gypsum crystals. Many of these cross fractures were as much as a half inch thick and pieces of gypsum this thickness and a foot long were removed from the shales. "Montana. — Overlying the Mancos is the Montana Mesa Verde formations which are essentially sandstones, shales, and grits, light gray to dark brown in color. Car- bonaceous shales with thick beds of workable coal occur near their base, while sandstone occurs in the upper part. ' Transition marked by increase of sandstone upward and appearance of brackish and fresh water arise instead of marine conditions.' "The upper layers of sandstone are often found in thick lenses and in many places contain high percentages of gypsum. The vegetation accumulated in these shallow seas resulted in the formation of coal. The sea seems to have increased sufficiently after the formation of the coal 26 THE ORIGIN OF ALKALI so the area was covered with thick la}'crs of sand and shale, but the sea does not seem to have continued without interruption. Arid conditions seem to have again pre- vailed and the sea was reduced so that isolated portions became brackish and from these isolated waters gypsum and other salts were precipitated. **At the end of the Montana series the sea seems to have again entirely disappeared and the area was subject to erosion. "In the beginning of Tertiary times the section was "!S^ / ,i Fig. 2. — Mancos Shale Hill. Soil from this Formation IS High in Alkali. again covered with inland seas over much the same area as that occupied by the upper Cretaceous. The lower portion of these Tertiary deposits consisted of yellow and reddish-yellow sandy clays with regularly bedded sand- stones, with some conglomerates near the base, over which were deposited thin beds of light-colored sandstones asso- ciated over much of the area, especially in Utah, with rhyolitic ash beds and fresh-water deposits. In some places the ashes show distinct stratification as though they ARMS OF THE OCEAN 27 had fallen into the inland sea and had been worked over by the water. "The upper part of the Tertiary is composed of shaly sandstone and arenaceous shale, and in some sections thick beds of subbituminous coals. The shale and much of the sandstone are gypsiferous and in many places con- tain high percentages of sodium salts. "Near the close of the period the high evaporation seems to have so reduced the sea that parts of it became isolated lakes and from these brackish deposits were precipitated the salts and gj-psum in question. "The Green River formation is composed essentially of light-colored thinly laminated beds, characterized by light-colored thin bedded shales. In appearance these shales of the Green River fonnation are much like those of the Mancos, especially some of the light-colored and thinner beds. "The Green River shales weather into a series of 'bad lands, and it is not an unusual thing to have a large area entirely devoid of plants." Arms of the Ocean. — Many soils have been formed by deltas of streams deposited in the ocean. These sometimes enclose portions of the ocean which may be shut off from the main body of water. The inclosed salt water gradually evaporates and leaves deposits of soluble salts or an alkali condition in the soil. This may be either a surface ac- cumulation that is comparatively easy to remove, or the salts may extend to considerable depth and be very difficult to handle. The type depends on the way in which the soil was laid down and the nature of the area of inclosed sea water. Subsequent deposits of soil may leave the alkali at considerable depths. The alkali land of the lower Nile Valley as well as the small alkali tract along 28 THE ORIGIN OF ALKALI the coast of Southern CaHfornia derived their soluble salts from ocean water, which was inclosed in arms shut off from the main body of the ocean. Evaporation of Saline Lakes. — In arid countries nu- merous lakes without an outlet to the sea are found. All the water running into them is evaporated leaving the dissolved material to be gradually concentrated until the waters become saturated. Around the bodies of these lakes the soil is likely to be high in soluble salts. Arms of the lake may be shut off in the manner already described. These become centers of local salt accumulation. The lands for some distance surrounding these saline lakes are likely to be somewhat impregnated with alkali, but as the water is approached the concentration is generally in- creased. There is usually a fringe near the lake that is entirely unproductive. This is surrounded by a zone in which only alkali-resistant plants grow, and still farther away the less-resistant plants are found. The Great Salt Lake in Utah is an example of this kind. Formation of Soluble Carbonates. — On account of their soluble action on the organic matter of the soil and the hard crust which they form on the soil, the soluble car- bonates are, of all the soluble salts, most to be dreaded. Fortunately, they are not so widespread in their occurrence as are the chlorides and sulphates. The comparatively insoluble carbonates of calcium and magnesium are very abundant but, being only slightly soluble, they are seldom if ever harmful to plants. The exact method of soluble-carbonate formation is not well known. Cameron (3), from studies of greasewood and the creosote bush, held that these plants are instru- mental in converting the neutral salts into carbonates. Aladjem (i), from laboratory experiments with soil kept FORMATION OF SOLUBLE CARBONATES 29 in a water-logged condition and to which nitrates were added, conckided that sodium carbonate is reachly formed from the nitrates in a water-logged soil. Treitz (22) concluded from his studies of alkali soils of Hungary that the soluble salts found in them are derived from the ash constituents of the plants produced on the soil and that the first and most necessary condition for the formation of sodium compounds, particularly the carbonates, is a calcareous subsoil, carbonates of the alkali being formed by the action of calcium carbonate on the humates, sulphates, and chlorides of the alkalies. From a study of water extracts of typical alkah soils and of soils to which various salts were added, Cedroits (5) concluded that sodium carbonate is not formed in the soil by direct reaction between sodium chloride and calcium carbonate, but that the sodi.um of the chloride replaces other bases — potassium, calcium, and magnesium — in humates and silicates, and the latter give up soda to the soil solution when the excess of soluble sodium salts is removed. Kelley (13) and Breazeale (2) have concluded that sodium nitrate reacts with calcium carbonate in the for- mation of small quantities of sodium carbonate. In dis- cussing this reaction Breazeale has the following to say: "In the reaction between sodium nitrate (or sodium chloride or sodium sulphate) and calcium carbonate, resulting in the formation of sodium carbonate, the presence of relatively small amounts of calcium nitrate or calcium chloride in the reaction impedes and may prevent the formation of sodium carbonate. The presence of a satu- rated solution of calcium sulphate in this reaction does not entirely stop the formation of sodium carbonate. Sodium nitrate, sodium chloride, and sodium sulphate in 30 THE ORIGIN OF ALKALI the presence of carbon dioxide react with calcium carbonate, with the formation of sodium bicarbonate. The presence of relatively small amounts of calcium nitrate or calcium chloride in this reaction impedes and finally prevents the formation of sodium bicarbonate. The presence of cal- cium sulphate has no efifect in preventing the formation of sodium bicarbonate when sodium sulphate, or a mixture containing sodium sulphate, reacts with calcium carbonate. Sodium nitrate, sodium chloride, and sodium sulphate react with calcium carbonate in the soil with the formation of sodium carbonate (black alkali)." Nitrate Formation. — In alkali areas in many parts of several western states, certain brown-colored spots are found to contain large quantities of nitrates. Headden (lo, ii) and Sackett and Isham (15) believe that these nitrates are formed within the soil by the action of non- symbiotic nitrogen-fixing bacteria. Stewart and Greaves and Stewart and Peterson (17, 16, 18) are convinced, however, that large quantities of nitrates seep into the soil with the other salts from the country rock and that local nitrogen fixation is a minor matter in the accumulation of sodium nitrate in alkali soils. Localization mentioned by Headden is claimed by him to preclude the theory of transportation and concentration in some cases. He states that certain of the spots are in the center of the valley the soil of which is so deep as to preclude the theory of transportation. He also says the ground water about and beneath the spots is not high in nitrates, which again apparently contradicts Stewart and Peterson's theory. Concentration by Irrigation Water. — Whatever the original source of alkali in the soil, one fact has been well demonstrated. The condition may be greatly aggravated CONCENTRATION BY IRRIGATION WATER 31 by the improper use of irrigation water. The author (8) and many other workers have shown that the soluble salts arc carried ihrou^^di the soil very readily by irrigation water. In some soils, like those in parts of the large in- terior valleys of California, the original salt content, though high, was not sufficiently high to prohibit the growth of crops. After irrigation the salts are leached from the higher land and carried to the lower, here to be concentrated at the surface until the amount becomes too great for ordinary crops to grow successfully. This con- dition is found to an extent in practically every large irrigated section of the world. Methods of preventing accumulation in this way will be more fully discussed in a later chapter. Considerable salt may also be added directly to the land by the use of irrigation water carrying large quantities of soluble salts. This method of contamination is dis- cussed rather fully in Chapter XV. Relation of Origin to Methods of Treatment. — An understanding of the origin of the alkali in a given area is essential to an intelligent treatment of the condition. This is as true in handling a soil as in treating a human disease. A physician who would give a remedy for a headache without seeking the cause of the trouble might entirely fail in curing. He might in any case give some simple treatment that w^ould be harmless, but a really intelligent treatment would be founded on a knowledge of the cause of the trouble. Likewise in handling alkali land the source of the salt should be known. In one region an irrigation canal passed through a shale hill that was very high in soluble salts. Large quantities were dissolved and taken directly into the stream. Seepage was also excessive and much alkali was carried to the 32 THE ORIGIN OF ALKALI lower land by the seepage water. The land was finally drained, but the alkali content of the soil was not reduced since the quantity added was greater than that lost by drainage. Lining the canal through the alkali-charged shale corrected the entire matter. Soil experts and drain- age engineers, before deciding on the methods of reclaim- ing any alkali tract, should discover all probable sources of the alkali in the area under consideration and select their methods of reclamation accordingly. REFERENCES 1. Aladjem, R. Decomposition of Nitrates as a Possible Cause of For- mation of Sodium Carbonates in Egyptian Soils. Cairo Sci. Jour. 6 (1912), No. 75, pp. 301-302. 2. Breazeale, J. F. Formation of Black Alkali (Sodium Carbonate) in Calcareous Soils. Jour. Agr. Res. 10 (Sept. 10, 1917), pp. 541- 59°- 3. Cameron, F. K. Formation of Sodium Carbonate, or Black Alkali, by Plants. U. S. D. A. Rpt. No. 71 (1902), pp. 61-70. 4. Cameron, F. K. The Soil Solution, pp. 1 10-125. (Easton, Pa. 1911.) 5. Cedroits, K. K. Colloid Chemistry in the Study of Soils. Russ. Jour. Exp. Landvv. 13 (1912), pp. 363-420. (Abs. E. S. R. 28, p. 516.) 6. Clarke, F. W. The Data of Geochemistry. U. S. Geol. Survey, Bui. 616 (1916), pp. 22-35. 7. DoRSEY, C. W. Alkali Soils of the United States. U. S. D. A. Bur. of Soils, Bui. 35 (1906), 196 pp. 8. Harris, F. S. The Movement of Soluble Salts with the Soil Moisture Utah Sta. Bui. 139 (1915), pp. 119-124. 9. Headuen, W. p. Alkahes in Colorado (including Nitrates). Colo. Sta. Bui. 239 (1918), 58 pp. 10. Headden, W. p. The Fixation of Nitrogen in Some Colorado Soils. Colo. Sta. Bui. 186 (1913), pp. 3-47. 11. Headden, W. P. The Fixation of Nitrogen. Colo. Sta. Buls. 155 (1910), 48 pp. and 178 (1911), pp. 3-96. 12. Hilgard, E. W. Soils, pp. 422-423. (New York, 1906.) 13. Kelley, W. P. The Effects of Nitrate of Soda on Soils. Cal. Sta. Rpt. 1916, p. 59. rp:ferenci:s 33 14. Knight, W. C, and Slossok, E. C. Alkali Lakes and Deposits. Wyo. Sta. Bui. 49 (1901), pp. 75-79. 15. Sackett, W. G., and Isham, R. M. Origin of the "Niter Spots" in Certain Western Soils. Science, n. ser. 42 (1915), pp. 452-453. 16. Stewart, R., and Peterson, W. Further Studies of the Nitric Nitrogen Content of the Country Rock. Utah Sta. Bui. 150 (1917), 20 pp. 17. Stewart, R., and Peterson, W. The Nitric Nitrogen Content of the Country Rock. Utah Sta. Bui. 134 (1914), pp. 421-465. Stewart, R., and Greaves, J. E. The Movement of Nitric Nitro- gen in Soil and Its Relation to "Nitrogen Tixation." Utah Sta. Bui. 114 (1911), pp. 181-194. 18. Stewart, R., and Peterson, W. Origin of Alkali. Jour. Agr. Res. Vol. 10 (Aug. 13, 1917), pp. 331-353- 19. Stewart, R., and Peterson, W. The Origin of "Niter Spots" in Certain Western Soils. Jour. Am. Soc. Agron. Vol. 6 (1915), pp. 241-248. 20. Traphagen, F. W. The Alkali Soils of Montana. Mont. Sta. Bui. 18 (1898), pp. 22-23. 21. Traphagen, F. W. The AlkaH Soils of Montana. Mont. Sta. Bui. 54 (1904), PP- 91-93- 22. Treitz, P. The Alkali Soils of the Great Hungarian Alfold -Foldtani Kozlony, 38 (1908), pp. 106-131. (Abs. E. S. R. 20, p. 818.) 23. Whitney, M., and Means, T. H. The Alkali Soils of the Yellowstone Valley. U. S. D. A. Bur. of Soils, Bui. 14 (1898), pp. 9-20. CHAPTER IV NATURE OF ALKALI INJURY TO THE PLANT Many of the general effects of excessive quantities of soluble salts in the soil are well known, but there still remain to be worked out a number of important problems, the solution of which will throw a great deal of light on the exact nature of alkali injury. Every farmer in alkali regions recognizes by the appearance of the soil and the limitations in crop growth the presence of alkali, but the actual underlying causes of the abnormal conditions are in part a mystery to even the most profound students of the subject. Prevention of Water Absorption. — Doubtless one of the very important injuries caused by alkali results from checked absorption of water by plants. It matters not how desirable other conditions are — how much plant- food is available, how deep the soil, or how favorable the temperature — if the plant cannot secure water it can make no growth. Roots absorb water from the soil by the process of osmosis. Because the cell-sap of root-hairs contains a stronger solution than the soil, water passes through the cell-wall and plasma membrane into the cell where it assists in the vital processes of the plant. Since carbohydrates are constantly being elaborated in the leaves, the cell-sap farthest from the roots is more con- centrated than that which has recently been diluted in the roots by the entrance of water from the soil. The transpi- 34 PREVENTION OF WATER ABSORPTION 35 Fig. 3. — Upper, Normal Plant Cell. Lower, Cell THAT HAS BEEN PlASMOLYZED. ration of water from the leaves also tends to concentrate the cell-sap in the leaves. This continuous diluting in the roots and concentration in the leaves causes a move- ment of water from root cells upward toward the leaf 36 NATURE OF ALKALI INJURY TO THE PLANT cells. This movement is necessary to the normal function- ing of plants. An ordinary plant, such as wheat, absorbs and transpires several times its own weight of water each day. Should this movement be reduced, the growth of the plant is retarded. If it is entirely shut off the plant dies, as pointed out by Pfeffer (12). The exact action that takes place when a plant cell comes in contact with a solution more concentrated than its own content was long ago pointed out by deVries (15) and Pfeffer (11). Water passes out of the cell and the plasma membrane draws away from the cell-wall leaving the cell in a plasmolyzed condition. The rapidity of plasmolysis depends on the relative concentration of the solution inside and outside of the cell. So well known is this phenomenon that the method is used constantly in de- termining the concentration of the cell-sap under various conditions. The above conception helps to explain the observed action of plants. The soil solution of land high in alkali is stronger than the cell-sap; therefore, no plant growth takes place. In other land where there is less alkali, the concentration may be just strong enough to reduce the rate of water absorption but not enough to shut it off entirely. Under this condition the crop yield would be reduced. Thus, every gradation from a normal crop to no crop at all may be found in a single field. Under some conditions, such as after irrigation or heavy rains, alkali may be so diffused throughout the soil that the concentration at any point is not sufficient to prevent the crop from beginning a good growth. As the season ad- vances, the salt may accumulate at the surface of the soil until irrigation water is applied. It may then be washed down to the roots in a concentrated form causing EFFECTS ON GERMINATION 37 the death of the plant. The farmer says his crop has been burned since it has that appearance. As a matter of fact water may have been drawn out of the plant through the roots. This, taken with the loss by transpiration, des- sicates the plant to the point at which it dies. Effects on Germination. — Before a:* seed can germinate it must absorb water. Ordinarily when a seed is planted in a moist soil it absorbs moisture and swells. At once '"Tff ''■!'} I I l-'iG. 4. — An Orchard Planted on Land that Came from a Formation High in Soluble Salts. The Salts h.vd Killed Most of the Trees BY the Second Year. the enzymes contained in the seed convert part of the starch into sugar which increases the strength of the solu- tion in the seed. This in turn hastens absorption and the seed soon contains sufficient moisture with which to carry on rapid cell division and growth. Within a few days a root is sent out, then a shoot for the top, and a new plant is growing. When a seed is placed in a strong salt solution or a soil that has a large amount of alkali, it does not absorb mois- ture; consequently, it lies dormant the same as it would in dry soil or in dry air. The coating on the seed protects it from absorbing most of the salts. It may not be injured, and as pointed out by Slosson (13) it will germinate when removed from the alkali soil to conditions favoring ger- 38 NATURE OF ALKALI INJURY TO THE PLANT mination. Under similar conditions, a plant would not only be hindered from growing, but would actually be killed. A salt solution not sufficiently strong to prevent entirely the germination of seeds may greatly delay it. The author has shown (3) that seeds which normally germinate in six days may be delayed as long as twenty-one days under conditions in every way similar except in the salt content of the soil. This delayed germination may be very serious in regions where the normal length of the growing season is greater than that required for maturity of the crop even if growth after germination were satisfactory. Effect on Structure of the Plant. — Vegetation growing on alkaU soil has a characteristic appearance similar to that found growing under desert conditions. It generally lacks that bright green appearance of vigorous and healthy growth. This condition is observed even in water-logged land where there is an ample supply of moisture. A similar moisture supply without alkali would result in a succulent growth. Harter (4) examined the structure of plants to determine the effect of soluble salts in the soil. He found that culture in a soil containing considerable quantities of sodium chloride together with other salts produced measurable changes in the leaf structure of wheat, oats, and barley. The most notable modification produced was the conspicu- ous bloom or waxy deposit that formed on the surface of the leaves. This development of bloom was accompanied by an easily measured increase in the thickness of the cuticle and outer walls of the epidermal cells and by a marked decrease in their size. In regard to transpiration of the plants, it was found that when the alkali salts are present in sufficient con- INJURY AT THE SURFACE OF THE SOH. 39 centration to cause the modilications of structure noted, transpiration is much reduced. On the other hand, the same salts when present in amounts too small to produce any measurable influence upon structure have a decidedly stimulating elTect upon transpiration. Fig. s. — The Lo^\^LR Part of an Orchard beixg Killed by Alkali brought to the Surface by a Rising Water Table. Similar modifications in structure have been pointed out by Kearney (7) who shows that thickness of leaves and stems with zerophytic tendencies characterizes plants growing in a saline soil. Injury at the Surface of the Soil. — Orchards and \ine- yards in many cases ha\'e been planted in soils containing a rather high salt content, but not high enough to prevent growth. A root system may become thoroughly estab- lished in an untoxic lower layer of soil which is slightly 40 NATURE OF ALKALI INJURY TO THE PLANT alkaline and yet there may be a gradual accumulation of salt at the surface of the soil. This condition has the effect of corroding the plant and it often destroys the bark so thoroughly that the passage of elaborated food from leaves to roots is prevented. This injury is rather limited in the total damage done and may be overcome without great expense. Formerly it was thought that the principal injury to vegetation by alkali resulted from a corroding action. This is probably not the case, with the possible exception of the carbonates. The carbonates, in addition to any direct action on the plant itself, make the soil hard and a poor medium for the plant. REFERENCES 1. Breazeale, J. F. Effect of Sodium Salts in Water Cultures on the Absorption of Plant-food by Wheat Seedlings. Jour. Agr. Res. 7 (1916), pp. 407-416. 2. DuGGAR, B. M. Plant Physiology, pp. 64-83. (New York, 191 1.) 3. Harris, F. S. Effect of Alkali Salts in Soils on the Germination and Growth of Crops. Jour. Agr. Res. 5 (1915), pp. 1-52. 4. Harter, L. L. Influence of a Mixture of Soluble Salts, principally Sodium Chloride, upon the Leaf Structure and Transpiration of Wheat, Oats, and Barley. U. S. D. A. Bur. PI. Ind. Bui. 134 (1908), 19 pp. 5. Hicks, G. H. The Germination of Seeds as Affected by Certain Chemi- cal Fertilizers. U. S. D. A. Div. Botany, Bui. 24 (1900), 15 pp. 6. Hilgard, E. W. Soils, pp. 326-428. (New York, 1906.) 7. Kearney, T. H., and Cameron, F. K. Some Mutual Relations be- tween Alkali, Soils, and Vegetation. U. S. D. A. Rpt. 71 (1902), 60 pp. S. JosT, L. Plant Physiology, pp. 11-35. (Oxford, 1907.) 9. Kearney, T. H. Plant Life in Saline Soils. Jour. Wash. Acad, of Sci. Vol. 8 (1918). 10. MiCHEELS, H. The Mode of Action of Weak Solutions of Electro- lytes on Germination. Acad. Roy. Belg. CI. Soc. (1912), No. 11, pp. 753-765- (Abs. E. S. R. 29, p. 218.) REFERENCES 41 II. Pfeffer, W. Osmotischc UnlcTsiKluin^en (1S77), 236 pp. 1.'. Pfeffer, W. Physiology of Plants, Vol. i (1900), pp. 90-107; Vol. 2 (1903), pp. 249-258. 13. Slosson, E. E. Alkali SLudics. W'yo. Sla. Rpt. 1S99, 29 p[). 14. True, R. H. The Physiological Action of Certain Plasmolyzing Agents. Bot. Gaz. Vol. 26 (1898), pp. 407-416. 15. Vries, H. de. Eine Methode zur Analyse der Turgorkraft. Jahr. f. wiss. Bot. 14 (1884), pp. 427-601. CHAPTER V TOXIC LIMITS OF ALKALI Numerous attempts have been made to determine the approximate quantity of the different alkali salts, both singly and in various combinations, which may be with- stood successfully by crops. Some experimenters have confined their work almost entirely to held observations. Others have worked with natural alkaU soils from the fields or soils made alkaline by the addition of salts in definite quantities and sown to crops under laboratory conditions. Still others have used different solutions containing salts as the medium for determining the toxicity of salts to plants. Each method has both advantages and disadvantages. The field work has often been done by sampling soils showing injury to plants and also adjoining soils where the effects of the alkali could not be detected. These observations are usually taken after the crop has made considerable growth, when the extent of injury may be estimated by the appearance of the plants. Such deter- minations may not take into consideration conditions pre- vailing during the earlier stages of growth. The vigor and deHcacy of the plant at the time the alkali comes in contact with it appear to have much to do with its tolerance. Alfalfa, sugar-beets, and a number of other plants do not withstand alkali well in their seedling stages, but are among the most tolerant during later stages of growth. Most plants do better under alkali conditions as maturity 42 XUTRlEXr SOLUTIONS 43 ajiproaches. Since the conditions under which plants grow at different times is modified by rainfall, movement of ground water, evaporation, and other factors, an analvsis of the soils at a particular period of growth is not so definite for indicating toxicity as might be wished. Because of the difficulty in fixing definite toxic limits under field conditions, these observations will not be considered in the present discussion but will be reserved for Chapter XIV dealing with crops for alkali land. Toxicity in Solution. — Some of the first attempts to establish the toxic limits of alkali were made in solution cultures because the solution was easy to make up, easy to analyze subsequently where it was desired to learn the final concentration of the water, and because such com- plicating factors as absorption of the salts, moisture con- tent of the soil, and nature of the soil were eliminated. Some of the experiments were carried on in cultural media, such as Knop's solution, in an attem.pt to duphcate soil conditions as nearly as possible, whereas others were made in water containing only alkali salts. Nutrient Solutions. — Some of the nutrient-solution cultures were carried to later stages of growth than those with the toxic salts alone. Since, however, the strength of the nutrient solution, its composition, and other factors modify the results almost as much in some cases as the alkali salts the advantages of the culture media over the simple solutions are not so apparent. Plants are usually at their most critical life period in the seedling stages where they are still depending on the seed for their nu- trition. The results of LeClerc and Breazeale (17) show the tolerance of wheat seedlings for sodium chloride in culture solutions to be about 3000 parts per million, which is not essentially different from certain other results 44 TOXIC LIMITS OF ALKALI where the solution containing the alkali salts was tap water. Tottingham (29) did not find the introduction of potassium chloride or sodium chloride into Knop's solution to have any marked effect on wheat plants, although the sodium chloride depressed the dry weight and length of roots of buckwheat. Alkali Solutions. — - Alkali solutions have been used in a number of different ways to determine toxicity. Some experimenters have germinated the seed in the alkali solu- tions; others have used the alkali solutions in which to immerse the roots of the seedlings after they have germi- nated under normal conditions. Since conditions differ so widely under the two methods and because the time allowed for the alkali to become effective differs consider- ably, the two methods will be treated separately. Seed Germination. — Experiments with wheat in Wyoming (4, 27) show that salts hinder the absorption of water by the seed so that germination is retarded and that the kind of neutral salt is of less importance than the osmotic pressure of the solution. The work of Kearney and Cameron (14) on antagonism and of the author (10) apparently disprove the latter statement, however. From the Wyoming experiments which included salt solutions from 1000 to 90,000 parts per million in strength, it was found that inhibition was not retarded in as rapid pro- portion as the osmotic pressure of the solution was in- creased. Inhibition was apparently not influenced by the vitahty of the seed nor did the salts affect the vitahty of the seed when removed before sprouting. The weaker solutions up to 4000 parts per million of sodium sulphate, sodium chloride, magnesium sulphate, or sodium car- bonate had a beneficial effect on the germination of the seed and the growth of the plants. SEED GERMINATION 45 Miss ]\Iago\van (iq) states that alkali experiments are not reliable when they are continued only a week because the relative toxicity of the salts may change later. She found that although magnesium chloride was at first the most toxic of the chlorides, followed by sochum chloride, potassium chloride, and calcium chloride, this relation- ship did not hold throughout the experiment. Working with wheat seedlings in solutions of o.oi normal, or 585 parts per million, sodium chloride, 850 parts per million sodium nitrate, 746 parts per million potassium chloride, and loii parts per million potassium nitrate, ]\Iicheels (21) found chlorine more harmful than nitrate ions, and sodium more harmful than potassium ions. He ascribed the variation to physiological and not chemical differences, as did also Slosson and Buffum (27) working with wheat, rye, and beans in the common alkali salt solutions. Sodium carbonate was the only salt found causing other than physiological injury. Wyoming experiments (27) show the highest concentra- tion of salts not retarding germination of wheat and rye to be as follows: MgS04 Na2S04 NaCl Na.COa Wheat 10,000 7000 4000 4000 Rye 10,000 7000 4000 1000 The vitality and time to germinate were effected dele- teriously as the strength increased above the minimum. Rye was as a general rule more tolerant of the higher concentrations of these salts than was wheat. Sigmund (26) found 5000 parts per million of sodium chloride or of sodium carbonate retarded the germination of cereal seeds in . solutions of these salts. Vetch and rape seeds were killed in 5000 parts per million solutions 46 TOXIC LIMITS OF ALKALI of sodium carbonate, but neither they nor wheat were injured in 5000 parts i)er million of sodium bicarbonate. According to this author the highest strength of sodium chloride endurable by the cereals was 5000 parts per mil- lion, by legumes 3000 parts per million, and by rape 1000 parts per million. Jarius, as quoted by Kearney and Cameron (14), reports a stimulating effect on seeds of wheat, rye, rape, maize, beans, and vetch in a solution containing 4000 parts per milhon of sodium chloride. Storp, as quoted from Kearney and Cameron (14), found this salt to stimulate germination in solutions as strong as 100 parts per million. In his w^ork with solutions of sodium chloride in concentrations ranging from 1250 to 50,000 parts per million, Coupin (6) found the toxic hmits for wheat to be 18,000 parts per million, of lupine 22,000 parts per million, of maize 14,000 parts per million, of peas 12,000 parts per million, and of vetch 11,000 parts per million. In this author's experiment the endurance of the plant as a whole to the solution was taken to indicate the limit, whereas with some of the others the death of the root or some other part is sometimes taken to indicate the injury to the plant. He found the toxic limits for seashore plants to be several times that for the crop plants mentioned above. Nessler, who is quoted by Hicks (12), states that hemp seed was injured in germinating by 2500 parts per million of sodium chloride, clover by 5000 parts per mil- lion, and wheat by 10,000 parts per million. Rape seed was found to resist sodium chloride, potassium chloride, calcium nitrate, sodium nitrate, and potassium sulphate in concentrations as high as 5000 parts per million, but the vitality of wheat, rye, maize, beans, and peas was seriously injured when using solutions as strong as this (12). Sodium chloride had a stimulating effect. SEEDLINGS IN ALKALINE SOLUTIONS 47 Seedling Transference into Alkaline Solutions. This practice has been preferred to germinating and growing the plants in the alkaHne sokitions by some investigators. Certain experiments ha\e indicated that plants may gradually become accustomed to salts as they grow older so that the injurious strength of solution at one period may not be so at another. By dipping the seedlings into the alkali solutions at a definite period after germinating, it has been hoped that a better standard for comparing toxicity would be fixed. Fcr such work many standard conditions have been suggested but few of these standards have been accepted by other workers, so there is a wide difference in the conditions under which the toxicity of the plants have been determined. In the experiments of Kearney (13) and his co-workers the roots of the seedlings were placed in the alkali solu- tions for twenty-four hours and the death of the root tip was taken to indicate the toxic limit for the plant. As a result of this work, corn showed the toxic effect of mag- nesium less than other salts, but with lupines, alfalfa, wheat, sorghum, oats, cotton, and beets the magnesium compounds were considerably more toxic than other salts. The sodium chloride and sodium sulphate did not differ greatly in toxicity to the different plants in several cases, and the sodium carbonate was several times more toxic than these two salts in most cases. Corn, which is considered rather sensitive to alkah, endured more sodium carbonate than the other crops, whereas sorghum, cotton, and beets, which are usually resistant in soils, were affected most by this salt in solution. The limits for wheat were 650 parts per million of sodium carbonate, 2610 parts per million of sodium chloride, and 2830 parts per million of sodium sulphate. Comparing the two series with lupines 48 TOXIC LIMITS OF ALKALI it is seen that the variations are wide. In another experi- ment with lupine, where growth was prevented by the salts contained in the solutions, the magnesium salts were not so toxic as the carbonates of sodium, and the mag- nesium sulphate was the least toxic of all salts. This shows that very wide differences might be expected ac- cording to the method employed. True (30), using the above method for obtaining the toxic limit of lupine in sodium chloride solutions found it to be 3625 parts per million, which again shows the possible error. Coupin (5) allowed the plants to remain in the solutions until the whole plant showed the salts to be causing injury. His limits for lupine using sodium chloride, magnesium chloride, and magnesium sulphate were 12,000, 8000, and 10,000 parts per million for the respective solutions, which is about the same as the above results where growth was prevented. The resistance here is several times that found by Harter where the first injury was the point of indication rather than the death of the plant. Allowing the roots to remain in the salt solution twenty-one days and then weighing, the author (10) found wheat seedlings to produce about one-half as much as the check in the solutions containing 5000 parts per million of sodium carbonate, or in those containing over 10,000 parts per million of sodium chloride or sodium sulphate. Haselhoff (q) concluded that growth might be inhibited with a 5000-parts-per-million solution of sodium chloride and injury would result in the presence of 500 parts per million. Hansteen (8) states that 5000 parts per million of salts other than calcium are injurious when used singly, but when combined with lime the injury is greatly diminished. Others have found the same antagonistic effects of dif- IN SAND 49 ferent salts. This subject is reserved for Chapter VIII and will not be discussed here. A series of experiments was made by Marchal (20) to discover the effect of salts on the bacterial activities of tlic nodules of pea roots. He found alkaline nitrates in concentrations of 100 parts per million checked the tu- bercle production in water cultures. Ammonium salts were injurious in concentrations of 500 parts per million. Potassium salts at 5000 parts per million and sodium salts at T,^;^^ parts per million tended to retard symbiosis, Ijut calcium and magnesium salts favored it. Soil Results. — Soil studies of alkali have been found to show less variation for Like treatment than solution studies. Some of the other disadvantages of solution studies of the effect of alkali on the higher plants are that the seed in germination tests and the root system are placed in an unnatural environment, the air circulation being eliminated and the normal resistance of the soil being changed. Studies of plants in solutions compared with similar soil cultures have shown that physiological dis- turbances are more likely to occur in solutions than in soils; the root-hairs are less numerous and the roots grow longer and thinner in the solution than in the soil. In- dividuals show much more variation due to unfavorable causes in the solutions than in the soils even where the soil consists of sand containing practically no nourishment. In Sand. — The physical conditions under which the plants grow seem to have some influence on their natural development. The author (10) found that whereas wheat seedlings produced about a half normal crop of dry matter in a sand containing 1000 parts per million of sodium chloride in solution cultures, more than half a normal crop was obtained when the concentration was over 10,000 50 TOXIC LIMITS OF ALKALI parts per million of this salt. For sodium carbonate the relationship between sand and solution cultures was about looo and 5000 parts per million, respectively, and for sodium sulphate it was about 5000 to over 10,000 parts per million, respectively, for half-normal crops of dry matter. Le Clerc and Breazeale (17) found wheat seed- lings more tolerant for sodium chloride in sand than in solution. Breazeale (2) states that the reverse relation- i'lG. 0. Experiments tu Determine the Toxicity of Various Alkali Salts. ship for nutrient solutions holds, 300 parts per million of nutrient solution being the best concentration for wheat seedlings, while 2500 parts per million was best for them in sand. Others have found the latter relationship to hold for sand. The size of pure quartz sand particles ap- parently had no effect on the toxicity of alkali in tests made by Harris and Pittman (11), but the quantity of moisture in the soil had considerable influence. The differences which may be expected in alkali experi- ments with differing moisture contents are shown in tests IN SAND 51 made by the author (lo). 'J'he toxic limits of wheat for salts in a sand were as follows: sodium chloride with 12 per cent moisture 2900 parts per millon, with 18 per cent 57C0 parts per million; sodium carbonate with 12 per cent 2700 parts per million, with 21 per cent 3300 parts per million; sodium sulphate with 12 per cent 8000 parts per million, with 24 per cent 16,000 parts per million. When the salts were added dry to the soil rather than in solution as in the above experiments, the limits of tolerance were higher, but the quantity of moisture added to the soils would influence the permissible quantity even more in such experiments than where the solutions were added be- cause the quantity dissolved would be more dependent on the water present. In the work of Buffum and Slosson (4) sand was used as the medium for growing seed in a nutrient solution, an attempt being made to duplicate soil conditions as nearly as possible. Their work was with wheat and alfalfa in sand containing solutions with osmotic pressure equivalent to 2.03, 3.80, and 7.10 atmospheres which corresponds to 5000, 10,060, and 20,000 parts per million of sodium sul- phate, or 2700, 5100, and 9700 parts per million of sodium chloride. The conclusions were that the lower concentra- tions of the salts were stimulating to the plants bu:, that the higher ones were harmful. Solutions of sodium sul- phate, potassium sulphate, sodium chloride, and potassium chloride were all about equally harmful to those plants at the same osmotic pressures when based on germination and several other observations of the growing plants. A series of germination experiments in a sand by Stew- art (28) showed that 10,000 parts per million of sodium sulphate was generally fatal to seeds of barley, rye, wheat, oats, peas, alfalfa, and red and white clovers. The re- 52 TOXIC LIMITS OF ALKALI sistance of the plants was about in the order given, barley being most tolerant. About 5000 parts per million of sodium carbonate or sodium chloride was fatal to the germination of these plants, and, excepting that peas were the most resistant to sodium carbonate and alfalfa was weakest for those salts, the order of toxicity was about as given above. Oats and mustard were found more resistant than flax for sodium chloride and sodium sulphate in pots of sand containing 315 to 1889 parts per million of these salts. Some influence of sodium sulphate was perceptible at the higher concentrations and the sodium chloride caused injury to the oats and mustard in the larger quantities. Wheat, oats, and peas failed to grow in soils containing 350 parts per million of chlorides but survived in the presence of 10,000 parts per million of total salts. Wheat and oats could withstand 20,000 parts per million of total salts where the chlorine content was less than 1250 parts per million. Claudel and Crochetelle (12) found that sodium nitrate in concentrations of 2000 parts per million prevented the germination of buckwheat and beans, injured or checked the germination of beet seed, and badly injured those of clover. However, it had very little effect on wheat and bar- ley seed. Buckwheat was considerably, and clover slightly, affected by 1000 parts per million. Barley was the only crop able to withstand 5000 parts per million of this salt. From the above discussion of the effects of alkali in sand on plants, it is seen that where allowance is made for the difference in the method of arrivmg at the toxic limits, the results are fairly uniform when compared with those of solution determinations. The two salts, sodium car- bonate and sodium chloride, are nearly the same in toxicity, IN LOAM SOIL 53 while sodium sulphate is considerably less harmful than the former two salts. In Loam Soil. — From a i)ractical point of view loam soil is a much more desirable medium for studying the effect of alkali on plants tlian is either sand or a solution. Absorption, antagonism, and physical conditions must all eventually be taken into consideration before the real toxic effect of the salts under normal conditions can be arrived at correctly. The use of loam, or other soil containing organic matter and having high absorptive properties, complicates the determination of the toxicity of salts. Harris and Pitt- man (ii) found that of two soils containing equal quantities of alkali and equivalent moisture contents, wheat on the soil with highest organic matter was injured less than where the organic matter was about as it is in ordinary loam. The organic matter appeared to remove sodium carbonate from the soil solution so that tliis salt appeared less toxic than has usually been ascribed to it from solu- tion or sand cultures or field extraction experiments. Wheat plants tolerated more alkali in a loam than in either a sand or clay and more in a coarse loam than a finer one with the same percentage of moisture, although with equivalent moisture contents the coarser loam was less tolerant than the liner. The toxicity of the salts de- creased with increasing percentages of soil moisture up to the maximum moisture content producing good crops. Changing the moisture relationship of the soil influenced the toxicity of sodium chloride and sodium sulphate more than did changing the organic matter, but the organic matter had the greater influence for sodium carbonate. High organic matter and moisture content offered the most favorable conditions for alkali toleration. 54 TOXIC LIMITS OF ALKALI The work of Haselhoff (9) on heavy loam and clay soils led him to conclude that because these soils absorb chlorine from the solutions of chlorides and thereby gradu- ally destroy the physical condition of the soil, the injurious influence of chloride solutions on soil productiveness and crop yield takes place gradually. Le Clerc and Breazeale (17) found the greater tolerance of wheat seedlings to sodium chJoride in clay as compared 'rfrrrrvrrrrf. Fig. 7. — Growth of Wheat with Various Concentrations OF Different Salts. to sand and solution cultures to be due to the lime which the clay contained. Shutt (25) found that calcium oxide was very effective and calcium carbonate less so in correct- ing the toxicity of soil containing 50,000 parts per million of magnesium sulphate. Even when calcium oxide was used, germination was still retarded but a larger percent- age of the plants grew and the growth was more healthy. This antagonistic action of calcium and other salts will be taken up in greater detail in Chapter VIII. In the work done on the germination and growth of plants in Wyoming by Buffum (2), alkali soils were leached of their alkali and then made up to the required percent- IN LOAM SOIL 55 age by the addition of the ]3ure salts in one part of the experiment and in the other the soil was leached of a por- tion of its alkali sufficient to obtain the required alkali content. The alkali was two-thirds sodium sulphate and one- third magnesium sulphate and in concentrations from 10,000 to 50,000 parts per million. The test showed that in a soil containing 2^ per cent moisture, rye germinated almost normally with 22,500 parts per million of these salts; barley nearly perfect with 10,000 but less than half normal with 22,500 parts per million in the natural alkali soil; wheat about two-thirds normal with 10,000 parts per million; alfalfa perfect with 10,000 parts per million but producing hardly a sprout in 22,500 parts per million; while turnips and oats produced less than one-half normal germination in soil containing 10,000 parts per million. The time taken for the seeds to germinate was increased in proportion to the salt present even for the lower quan- tities of alkali. Table IX summarizes the work of Guthrie and Helms (7) in a rich garden loam soil mixed with nearly an equal c|uantity of light sand. Table IX. Concentrations of OF Various Salts Affecting the Crops Grow FH Sodium Chloride Sodium Carbonate Wheat Barley Rye Wheat Barley Rye Germination affected Germination prevented Growth affected 500 2000 500 2000 1000 2500 1000 2000 1000 4000 1500 2000 3000 5000 1000 4000 2500 &000 1500 4000 2500 5000 2500 Growth prevented 4000 From the figures it is seen that the resistance of seed to alkali during germination is not always the same as the 56 TOXIC LIMITS OF ALKALI resistance during later growth, and the relation between germination and subsequent growth differs for these two salts. With the following quantities of alkali added to loam soil the author (lo) found the plants indicated in the table to produce about half-normal crops of dry matter. Table X. Quantities of Various Salts Added to the Soil WHICH Reduced the Yield of Crops to about Half Normal Crop Barley Oats Wheat. : . . . Alfalfa Sugar-beets . Corn I'ield peas . . Sodium Chloride 5000 4000 3000 3000 3000 3000 3000 Sodium Carbonate 10,000 8,000 0,000 6,000 6,000 4,000 4,000 Sodium Sulphate Above 10,000 " 10,000 " 10,000 " 10,000 " 10,000 " 10,000 " 9,000 It will be noted that the figures by the author are con- siderably above those of Guthrie and Helms, but that the carbonates when added to the soil in each case were less harmful than the sodium chloride. In the sand soil the sodium chloride and sodium carbonate were noted to be nearly equally toxic and for the field results presented in Chapter XIV the sodium carbonate shows nearly the reverse relationsliip to this. The low toxicity of the salts as compared with those for field determinations are probably due partly to absorption of some of the salts and to the even distribution and favorable moisture content possible in controlled experiments compared with field conditions. Of the salts used in the experiments of the author with wheat seedlings, the order of toxicity for salts added from highest to lowest was as follows: sodium chloride, calcium chloride, potassium chloride, sodium ni- trate, magnesium chloride, potassium nitrate, magnesium IN LOAM SOIL 57 nitrate, sodium carbonate, potassium carbonate, sodium sulphate, i)otassium suli)hate, and magnesium sulphate. This order docs not hold when the concentration is determined by an anal}sis of the soil. The anions were found to affect the toxicity more than the cation, the chloride being the most toxic anion and sodium the most toxic cation. Bancroft (i), in his work with beans growing in large pots to which alkali was added from below after the plants were growing until they wilted and died, found the fol- lowing quantities of salts just killed the plants: magnesium chloride, 2640 parts per million; sodium carbonate, 2710 parts per million; sodium nitrate, 3700 parts per million; sodium chloride, 5660 parts per million; magnesium sul- phate, 5820 parts per million; sodium sulphate, 6810 parts per million; and sodium bicarbonate, 12,300 parts per million. In germination tests on sugar-beet seed by Headden (Colo. Sta. Bui. 46) it was found that while 1000 parts per million of sodium carbonate permitted the seed to germinate freely, 5000 parts per million w^as injurious. The limit for sodium sulphate was about 8000 and for a mixture of the tw^o about the same as the sodium carbonate. From the foregoing discussion of the various experi- ments with alkali under different conditions and from the results given in Chapter XIV on crops for alkali land, it is seen that the limits vary so widely because of the dif- ferent methods of arriving at these limits, that unless the conditions can be duplicated, considerable error might result from estimates secured by different experimenters. The estimates under field conditions would be expected to range through a wider limit because of the complicated changes within the soils and because of differences in de- 58 TOXIC LIMITS OF ALKALI termining the salts in the soils. With laboratory experi- ments, the same allowances must be made because of the various complicating factors such as moisture content, organic matter, antagonism of the salts, absorption, and differences in tolerance of the plants at different times. REFERENCES 1. Bancroft, R. L. The Alkali Soils of Iowa. Iowa Sta. Bui. 177 (1918) 2. Breazeale, J. F. Effect of the Concentration of the Nutrient Solu- tion upon Wheat Cultures. Science, n. ser. 22 (1905), pp. 146-149. 3. Buefum, B. C. Alkali. Wyo. Sta. Bui. 29 (1896), pp. 219-253. 4. BuFFUM, B. C. Alkali Studies, III. Wyo. Sta. Rpt. 1899, p. 40. Also Rpt. for 1900. 5. CoupiN, H. On the Poisonous Properties ot Compounds of Sodium, Potassium, and Ammonium. Rev. Gen. Bot. 12 (1900), No. 137, pp. 177-193. (Abs. E. S. R. 12, pp. 717-718.) 6. CoupiN, H. On the Poisonous Properties of Sodium Chloride and Sea Waters toward Plants. Rev. Gen. Bot. 10 (1898), No. 113, pp. 177- 190, figs. 3. (Abs. E. S. R. II, p. 24.) 7. Guthrie, F. B., and Helms, R. Pot Experiments to Determine the Limits of Endurance of Different Farm Crops for Certain Injurious Substances. Agr. Gaz. N. S. Wales, 14 (1903), No. 2, pp. 1 14-120. See also 16 (1905). 8. Hansteen, B. The Relation of Plants to Salts in Soils. Nyt. Mag, Naturvidensk. 47 (1909), No. 2, pp. 181-192. (Abs. E. S. R. 23, p. 28.) 9. Haselhoff, E. The Action of Chlorides on Soil and Plant. Fiihling's Landw. Ztg., 64 (1915), Nos. 19-20, pp. 478-508. (Abs. E. S. R. 35, pp. 423-424.) 10. Harris, F. S. Effect of Alkali Salts in Soils on the Germination and Growth of Crops. Jour. Agr. Res. Vol. 5 (1915), pp. 1-52. 11. Harris, F. S., and Pittman, D. W. Soil Factors Affecting the To.xic- ity of Alkali. Jour. Agr. Res. Vol. 15 (1918), pp. 287-319. 12. Hicks, G. H. The Germination of Seeds as Affected by Certain Chemical Fertilizers. U. S. D. A. Div. Bot. Bui. 24 (1900), p. 15. 13. Kearney, T. H. The Wilting Coefficient for Plants in Alkali Soils. U. S. D. A. Bur. PI. Ind. Cir. 109, pp. 17-25. 14. Kearney, T. H., and Cameron, F. K. The Effect upon Seeding Plants of Certain Components of Alkali Soils. U. S. D. A. Rpt. 71. pp. 7-60. ri:1'1-:rkxci:s 59 15. Kearney, T. II., and IIarter, L. L. 'J'hc C'om|)aralivc ToliraiKc of Various Plants for the Salts in Alkali Soils. U. S. D. A. Bur. PI. Ind. Bui. 113 (1907), p. 18. 16. Kossovicii, P. Alkali Soil;--: TlK-ir Inllucnce on Plants and the Methods of Examining Them. Zhur. Opuitn. Agron. (Jour. K.\p. Landw.), 4 (1903), No. i, pp. 1-42. (Ahs. E. S. R. 15, p. 22.) 17. Le Clerc, J. A., and Brkazeale, J. F. The EfTcct of Lime upon the Alkali Tolerance of Wheat Seedlings. Orig. Commun.,8th Internat. Cong. .\ppl. Chem. (Washington and New York), 26 (1912), Sect. Vla-XIb, app. p. 135. (Abs. E. S. R. 29, p. ^22.) 18. Lesage, p. The Limits of Germination of Seeds after being Placed in Salt Solution. Compt. Rend. Acad. Sci. (Paris), 156 (1913), No. 7, pp. 559-562. (Abs. i.. S. R. 29, p. 218.) 19. Magowan, Florence N. The To.xic Effect of Certain Common Salts of the Soil on Plants. Bot. Gaz. 45 (1908), No. i, pp. 45-49. 20. M.ARCiiAL, E. Influence of Mineral Salts on the Production of Tuber- cle on Pea Roots. Compt. Rend. Acad. Sci. (Paris), 133 (1901), No. 24, pp. 1032-1033. (.Abs. E. S. R. 13, p. 1017.) 21. MiCHEELS, H. The Influence of Chlorides and Nitrates of Potassium and Sodium on Germinating Plants. Internat. Ztschr. Phys. Chem. Biol. I (1914), Nos. 5-6, pp. 412-419. 22. MiYAKE, K. The Influence of Salts Common in .\Ikali Soils ujxin the Growth of the Rice Plant. Jour. BioL Chem. 16 (1913), No. 2, pp. 235-263. 23. MiYAKE, K. The Influence of Acids, Alkalies, and .\lkali Salts on the Growth of Rice Plants. Trans. Sopporo Nat. His. Soc. 5 (1913), No. I, pp. 91-95; abs. in Bot. Cent. 126 (1914), No. 22, p. 588. (Abs. E. S. R. 34, p. 31.) 24. Reveil. Recherches de physiologic vegetale de Taction des poisons sur les plantes. (Paris, 1865.) 25. Shutt, F. T. .\lkaline Soils of Canada. Can. Exp. Farms Rpt. 1893, pp. 135-140. 26. SiGMUND, W. Ueber die Einwirkung chcmischer agenticn auf die Kiemung. Landw. versuchst. 47 (1896), No. 2. 27. SLOS.SON, E. E., and Buffum, B. C. x\lkali Studies, III. Wyo. Sta. Bui. 39 (1898), pp. 35-56. 28. Stewart, J. Effect of .Alkali on Seed Germination. Utah Sta. Rpt. 1898, pp. xxvi-xxxv. 29. Tottingham, W. E. .\ Preliminary Study of the Influence of Chlorides on the Growth of Certain Agricultural Plants. Jour. Amer. Soc. Agr. II (1919), No. I, pp. 1-32. 30. True, R. H. The Toxic .Action ot Acids and Their Sodium Salts on Lupines. Amer. Jour. Sci. 4 ser. 9 (1900), No. 51, pp. 183-192. (Abs. E. S. R. 12, p. loio.) CHAPTER VI NATIVE VEGETATION AS AN INDICATOR OF ALKALI It is highly desirable that the prospective landowner should, by studying the trees, shrubs, and grasses, be able to say that the soil is deep, well-drained, fertile, free from injurious properties, and capable of producing profitable crops. Upon many soils the native plants tend to group themselves to the exclusion of nearly all other species. Generally when such grouping occurs, there is some pecu- liarity of the soil which is made evident by such grouping. The luxuriant growth of one species of plant to the exclu- sion, or the near exclusion, of other species affords an excellent index to the nature of the soil. How Plants Indicate the Soil. — Certain plants in arid regions are seldom found except when the soil contains alkali salts. Davy investigating in California (i) states that " there are at least 197 species natives of Cahfornia, which are restricted to alkali soils." Some of these plants seem to thrive only when some particular salt is present in certain strengths, resenting even small quantities of other salts. Other plants do well in the presence of any of the alkali salts so long as moisture or soil conditions are right. In each portion of the arid region may be found some plants which indicate extremely large quantities of salts when found alone. They indicate that so much alkali is present in the soil that the land is worthless for agri- 60 HOW PLANTS INDICATE THE SOIL 61 cultural plants without reclamation methods lirst being applied. These characteristic plants are generally recognized by the farmers of the district in which they occur, but the exact quahties of the soil and the possibilities of its reclamation are not so often known. The kind of plant also varies considerably even within relatively short distances be- tj^p 6t<**>-»gwg*'^- Fig. 8. — Alkali Crx'sts at thk Strface I'ri:\i:mtno the Growth of Practically all Vegetation. cause of difference in soil or drainage. Changes in climate or altitude also influence the t>pe of plant that indicates a particular type of soil. A number of studies of the characteristic plants of alkali lands have been made together with the kind and amounts of alkali present in soils on which they grew. From these studies fairly intelligent conclusions may be drawn as to the kind and quantity of alkali in the soil without making a chemical analysis. In using native vegetation to indicate the alkalinity of a soil, however, it is essential that judgment should not be 62 NATIVE VEGETATION AS AN INDICATOR passed when only a few scattered or stunted plants are found. Generally when such ' scattered alkah-indicating individuals are found the soil contains some alkali, but the quantity is not clearly indicated. It is only when the plants produce a vigorous growth and occupy the land to the exclusion of non-resistant — if not all other species of plants — that they may be taken to indicate the kind and quantity of alkali characteristic of their species. Fig. q. — Alkali Land which is Indicated by the Growth OF Shadscale. It should be kept in mind also that under certain condi- tions alkali-indicating plants may grow well where alkali may not be present in quantities injurious to general crops and that non-resistant plants may be growing well on land so strongly impregnated with alkali that farming would be practically impossible without reclamation. Such conditions as a shallow hardpan, a dry sandy layer of soil, or other conditions which cause the plants to suffer for want of water, as they do when in the presence of ex- cessive quantities of alkali, may allow the presence of the alkali-resistant plants in abundance to the exclusion of ALKALI-INDICATING PLANTS 63 others. On the other luiiul, shallow-rooted ])lants whidi cannot endure alkali may grow luxuriantly on land which contains alkali below the depth to which its roots feed but so near to the surface that when farming is attempted the land may soon be ruined. The latter condition is represented l)y the Bear River Valley, Utah, where sage brush, rabbit brush, and salt grass are growing on land practically free from alkali in the upper foot or so, but the soil to a depth of six feet contains from 6000 to 30,000 parts per million of salts, mostly sodium chloride. This salt is quickl}' concentrated near the surface when irrigation is practiced, making farming impossible. Alkali-indicating Plants. — Some of the characteristic plants of the western part of the United States which should, when present as a luxuriant growth upon the land, be regarded as indicating distinctly alkali soil, or soil which should be looked upon with suspicion until chemical analyses of it have been made, are given below. Well-defined alkali-indicating plants Inkweed, or saltwort {Sitacda spp.) Tussock grass, or purple top {Sporobolus airoides). Torr. Bushy samphire, or Kern greasewood (AUenrolfea occidentalis) (S. Wats.). O. Ktze. Dwarf samphire {Salicornia spp.) Greasewood {Sarcobalus vermiculalns) Alkali-heath (Frankenia grandifolia campcnstris). A. Gray Sjjike weed {Ilcmizonia pungens) Little rabbit brush (bushy goldenrod) {Isocoma veneta) H. R. K. (A. Gray) Arrow or irrigation weed {Pluchea servicea) (Nutt.). Coville. (Sometimes Piuchea borealis) Salt-bush or shadscale {A triplex conferlifolia. etc.) Kochia or white sage {Kochia veslita) Salt-grass {Distichlis spicata). Greene Cressa (Cressa crelica Iruxillensis). Choisy Rabbit brush (rayless or false goldenrod) {Cbrysothamnus spp.) 64 NATIVE VEGETATION AS AN INDICATOR Alkali-indicating plants not commonly forming the major portion of alkali-land vegetation Inhabiting Unoisl saline lands: Arrow grass {Triglocliin marilima and T. paliislris) L. (Across continent) Alkalimea-dow gTas?,{Puccinclliaairoiclcs. Nutt.) (Entire west. N. Mex.- Mont.) Marsh grass {Spartina gracilis. Trin.) (Oregon to Texas) Trailing buttercup {Hakrpcstcs cymbalaria. Pursh.) (Rocky Mts., n. seacoast) Shooting star or American cowslip {Dodccalhcon salinmn. Nels.) (Western Wyoming, Utah, Idaho) Glaux {Glaux maritima. L.) (Suljsaline soil west of ISTississippi) Aster {Aster angustus. T. and G.) (Colorado and Utah to Minnesota) Aster {Aster pauciflorus. Nutt.) (New Mexico, Arizona, Utah) Crepis {Crepis glauca. T. and G.) (West of Missouri to Nevada) Plowman's wort {Pluchea camphoraia) (Coast of Florida to Texas) Mousetail {Myosurus apelalus. Gay) (Western North America) Valeria {Valeriana Jurfurescens. Nels.) (Colorado and Wyoming) Pyrrocoma iiniflora. Greene. (Montana to Colorado and Utah) Rush {Scirpus nevadensis. Wats.) (Wyoming, California) Tuber bubrush {Scirpus pahidosus) Inhabiting soil not moist at the surface: Bud-brush {Artemisia spinescens. Eat.) (Colorado to Montana and west) Aster {Aster zylorhiza. Nutt.) (Southcentral Wyoming. Naked, clayey, saline) Pyrrocoma lanceolata. Greene (Saskatchewan. Northern Colorado and west to Nevada) Flaveria angtistifolia. Pers. (Eastern Colorado and New Mexico to western Texas) Pepper grass {Lepidium montanum. Nutt.) (Montana to New Mexico and westward) Wild barley {Hordeum nodosum. L.) (Arizona to Alaska) Wild rye (£/.vwn(5 5fl//;H/,f. Jones) (Wyoming and Utah. Saline situations) Goosefoot or pigweed {Chenopodium rubrum. L.) (Across continent north- ward) Goosefoot or pigweed {Chenopodium soccosum. Nels.) (Southern Wyoming) Monolepsis spp. (Colorado and westward. Saline soils) Botanically, probably half of the alkali-loving plants belong to the Chenopodiaceae, or goosefoot family, which DISCUSSION OI" PLANTS 65 includes beets, mangles, samphire, saltwort, salt-busli, and greasewood. Some of the smaller families such as Frankeniaceae, Plumbaginaceae, Rhizophoraceae, and Tama- ricaceae are noted for the alkali resistance of most of the species. Some other families, notably Cramincac, Cru- ciferae, and Compositac, contribute some of the more important plants found to do well on alkali lands. Discussion of Plants. — " Inkweed, or saltwort, is a perennial shrub with a small, fleshy, stem-like leaf. Each winter the plant dies down close to the ground leaving behind a dark-colored bush" (5). It is found on some of the worst alkali lands of California (i), in one in- stance being found on soil containing 38,000 parts per million of total salt in the top foot of soil, and it has been found growing luxuriantly with as high as 32,000 parts per million of total salts in the top foot of soil. Where growing luxuriantly, the soil has been found to contain 837 parts per million of sodium carbonate, and 3313 parts per million of sodium sulphate in the upper three feet of soil. It thus indicated a soil with a high content of black alkali. Where found in abundance the soil is generally of a heavy, sandy-loam or a clay-loam texture occurring on low-lying lands and reclaimable only at great expense. Because of the presence of black alkali the soil is puddled so badly that rainwater generally evapo- rates from it before it will penetrate. When found on the higher lands, the soil is generally underlain with a hard- pan near the surface. Tussock grass {S poroholus air aides) sometimes forais a coarse, matty or tree-like growth, the trunks of which are often from 18 to 20 inches high. It forms feathery purple panicles in late summer and is relished by stock better than most any other native alkali-resistant plant. Ani- 66 NATIVE VEGETATION AS AN INDICATOR mals eat only the grass part of the plant leaving the trunk- like stems behind. It is a good alkali indicator for the arid Southwest, but is not common north of the 40th parallel, or about the center of Utah and Nevada. It has been found growing in a soil with an alkali content of 31,190 parts per million in the upper four feet, although it makes its best growth with about 3000 parts per million Fig. 10. Greasewood and Shadscale. These Plants Indicate Alkali in the Soil. of total salts. Of the separate salts in soil on which the plants were growing vigorously, the following amounts were found: Sodium carbonate 1437 parts per million Sodium chloride 387 parts per million Sodium sulphate 1227 parts per million It has been found growing with over 10,000 parts per million of sodium chloride and 20,000 parts per million of sodium sulphate. The range of tolerance is great; hence, scattered individuals should not be taken to indicate ex- cessive quantities of alkali, although when thick and DISCUSSION OF PLANTS 67 vigorous, especially when occurring along with other alkali indicators, it may be safe to call the land unsuitable for farming. It may occur on dr}- prairie soils where very small quantities of alkali are present. Kern greasewood or bushy samphire {AUenrolJca occi- dentalis) is a shrubby evergreen bush i to 4 feet in height with numerous cylindrical, fleshy, practically leafless alternating branches, and with a large taproot. It is nearly always found on the low-lying, and generally clayey, soils with a plentiful supply of moisture. Soils on which it does well are usually saturated with water throughout the growing season, but may become "dry bogs" during part of the year. The salt content of such soils is almost invariably high, sometimes reaching over 30,000 (i, 2) parts per million of total salts with a good growth of the plant. It has been found to make a good growth in the presence of 300 parts per million of sodium carbonate, 13,000 parts per mDlion of sodium chloride, and 17,000 parts per million of sodium sulphate. It grows with a higher sodium chloride content than any other plant known at present. Soils on which this plant forms the major growth are usually hopelessly alkaline; even salt bushes fail on the soils on which Allenrolfea does best. The heavy soils make reclamation by drainage difficult so that such soils can seldom be used profitably. Dwarf samphire {Salicornia suhterminalis and other species) is a nearly leafless plant with cylindrical, fleshy, many-jointed, opposite branches. All soils upon which it has been found are excessively alkaline. It grows well on land with a total salt content of 27,000 (i, 2) parts per million in the upper four feet. Analyses of the soil on which it was growing well showed it to contain 757 parts per million of sodium carbonate, 7852 parts per mil- 68 NATIVE VEGETATION AS AN INDICATOR lion of sodium chloride, and 19,627 parts per million of sodium sulphate. Thus, it resists larger quantities of sodium chloride and sodium sulphate than most other plants. Both the seashore and the inland species indicate land which is useless for farming until reclaimed by pro- longed draining, which in many cases is at present un- economical. Greasewood {Sarcohatus vermiculatus) is one of the most common alkali-indicating plants found on moist saline Fig. II. — The Border between Greasewood and Salt Grass. The Land Increases in Alkali toward the Salt Grass. fiats of the intermountain country. Viewed at a distance the patches of greasewood have a pleasant bright-green color decidedly in contrast to much of the darker or gray- ish alkali vegetation. Besides the numerous sharp spines which protect the small fleshy leaves from browsing ani- mals, the plant is bitter and salty so that no useful animal will eat it. Although it has not been found on soil con- taining more than 8000 (4) parts per million of total salts in the upper feet, its large taproot has been found pene- trating soil with nearly double this amount of salt (mostly DISCUSSION OF PLANTS 69 sodium chloride). Hilgard (2) reports 1170 parts per million of sodium carbonate, 230 parts per million of sodium chloride, and 2260 parts per million of sodium sulphate as being characteristic quantities of the common alkali salts present where the plant does best and that its presence "invariably indicates a heavy impregnation of land with black alkali or carbonate of soda" (2, page 542). Although the latter statement is generally true, it has been found on land showing only sulphates, and Kearney and others (4) found it growing on land in Utah without sodium carbonate as a chaiacteristic salt. Kearney says it is not an infallible alkali indicator as it w^as found makinir its largest and thriftiest growth on dunes of pure sand. It is usually associated with a rich silty or sandy soil, moist in the upper foot and containing excessive quantities of salts. It will endure larger quantities of alkali than most alkali plants. Greasewood soils are sometimes too alkaline to permit profitable reclamation. Alkali-heath {Frankenia grandijolia campcnstris) is a perennial herb with opposite or clustered simple leaves and with a deep-rooted, flexible, wiry, rootstock. It is a hardy plant which often persists as a weed on cultivated land. Although it generally indicates strong alkali where it is growing luxuriantly, it will grow with a great varia- tion in alkali content — from about 200 to 31,000 (i, 2) parts per million of total salts. The optimum quantities found by Hilgard (2) ranged from about 4000 to 17,600 parts per million in the upper four feet of soil. Of this amount 43 to 1224 parts per million was sodium carbonate, 360 to 636 parts per million sodium chloride, and 2158 to 17,220 parts per million sodium sulphate. Hilgard re- gards land that grows this plant to be unlit for crops with- out reclamation, although Mackie (5) says it will generally 70 NATIVE VEGETATION AS AN INDICATOR contain comparatively small quantities of alkali, and where this bush is found growing uniformly over an area to the exclusion of the most resistant alkali indicators, the alkali is found below the surface from i to 3 feet in a free sand or sandy loam soil. This " land yields crops " of alfalfa and grain or orchards and can be kept free from injurious quantities of alkali by proper methods of irriga- tion and drainage." Cressa {Cressa cretica iruxillensis) is a perennial herb with a woody base from which many leafy branches ex- tend. The leaves are almost sessile and are characterized by their silky, villous, and hairy nature. Cressa is a com- mon sea-coast plant in many of the arid parts of the world. In the United States it is found along the Texas coast and scattered throughout California, extending at least to the Arizona line. Alkali-heath has been found growing with a higher total salt content than Cressa, but Cressa is a surer indicator of irreclaimable alkali land because the lower limit in which it grows is much higher. Although sulphates predominate in Cressa soil, it will be noticed that it does well with chlorides in quantities dangerous to ordinary crops. Salt-bush, or Shadscale {A triplex spp.), is of two types — the perennial, which is generally bushy or shrubby, and the type that occurs as an annual weed. The leaves are usually alternate, simple, and often silvery, scurfy, or having an ashen-gray color, the bush type often being mistaken for sagebrush. The bush belongs to the same family as the beet and it can readily be detected by its beet-like seeds. A number of the A triplex species grow in soil which contains little or no alkali, but the moisture conditions are generally unfavorable on any soil which has a vigorous growth of them, and most of the common DISCUSSION OF PLANTS 71 species of the western arid country produce their most luxuriant growth in the presence of dangerous quantities of alkali. Land upon which saltbush — either bush or weed — grows best is generally light and free from alkali in the top foot or so, but is underlain by heavier soil which is likely to contain large quantities of alkali. Such soils are seldom underlain by hardpan and are usually porous ■The L.\sr 1'laxt to Auwixix an Alkali Flat SO that they may be reclaimed by flooding. Crops can as a rule be grown on the soil on which saltbush occurs, but there is likely to be a rise of alkali where great care is not taken to prevent it. The alkali is likely to be of the white type entirely, although it will grow with as much as 1200 parts per million (2) sodium carbonate in the soil. The annual A triplexes are similar to the bushes in color and appearance of the leaves but do not have the persistent woody base of the latter. They range in height from about I to 4 feet. Land upon which A triplex forms the principal vegetation should be looked upon with suspicion 72 NATIVE VEGETATION AS AN INDICATOR until borings and analyses show it to be free from alkali, unless plans are laid for immediate drainage. Soils con- taining as much as 10,000 parts per million (3) of salts — mostly sodium chloride — but with the upper foot or so dry and free from alkali, have been found to produce excellent saltbushes. They grow equally well in the presence of nearly 8000 parts per million (2) of sodium sulphate. Because of the porous, dry, upper soil, and the tendency to have alkali beneath, such soils are ordinarily unfit for dry-farming. KocJiia, or White Sage ( Kochia hestita) , is a low-lying shrub with its branches close .to the ground and with a strong taproot which, however, seldom penetrates to a greater depth than one foot. New shoots are sent up from its roots. Its leaves are alternate, sessile, villous, narrow, and entire. The branches as well as the leaves are fre- quently covered with short woolly hairs. It is found in the intermountain country from Colorado to Nevada. Land upon which it occurs is usually free from injurious salts in the upper foot or so, some observations showing the upper foot to contain about 1200 parts per million of total salts (4) , but the soil beneath which its roots feed is almost invariably impregnated with so much alkali that deeper rooting plants, such as the sagebrush {Artemesia tridentata) cannot exist. Kochia itself is not alkali resistant, but where it exists to the exclusion of sagebrush and similar nonresistant plants the lower depths of soil are either high in alkali or underlain at shallow depths with a hardpan which prevents deep penetration of roots. Either con- dition makes the land undesirable for general farming be- cause of the likelihood of a rise of alkah. Kochia land frequently contains some black alkali and the soil is often rather impervious so that reclamation is difficult. OTHER PLANTS 73 Salt-grass {DislicJilis spicala) occurs throughout the world, being the most common plant found on alkali lands. It grows well on land so free from alkali that some of the common alkali- loving plants such as grease wood fail, but can withstand and make a good growth with as much as 24,000 parts per million of total salts in the soil. No preference is shown for any of the alkali salts. The high- est quantities found in soil on which it grew well are as follows : Sodium carbonate 8517 parts per million Sodium chloride 4398 parts per million Sodium sulphate 2750 parts per million These quantities are only suggestive, however, as great variations are found wherever the grass is found. It is a poor indicator of alkali either quantitatively or quali- tatively, but when taken together with other plants grow- ing with it something of the nature of the land may be indicated. Other Plants. — A number of other plants which do well on alkali soils, but which are not so distinctive as a general rule, are the following: Rabbit brush or false golden-rod {Chrysothamnus spp.) which is cluster-flowered and woody-based; Plowman's wort {Pluchea camphorata (i) DC), a spicy or salt march Fleabane found in the marshes of Texas and Mexico as well as on the eastern and southern coast of the United States; little rabbit brush {Isocoma veneta Grey) a perennial composite bush about 18 inches high with a sparse, smooth, dark-green foliage usually growing in deep loamy soils with a medium salt content; spike weed {Hemizonia pungcns), a yellow- flowered spiny composite which grows in a dense mass to the exclusion of most other plants on comparatively weak alkali land with fair drainage; arrow or irrigation 74 NATIVE VEGETATION AS AN INDICATOR weed {Pleuchea borealis), a composite with a brush-like head supported on a stem 4 to 8 feet high wliich tolerates a limited quantity of alkali on a porous, deep, well-drained soil. Plants other than those discussed above are char- acteristic of alkali lands in their respective districts, but sufhcient data are not at hand to determine their exact reliability as to alkali resistance. Many other plants Fig. 13. — Plants Growing at the Top of Sand Dunes, the Only Place where the Alkali is not too Strong for plant Growth. grow upon alkali land during the wet season when the soil solution is dilute, but none of them can be classified as distinctive in determining soil alkali conditions. Description of Alkali-indicating Plants. — AllenroJJca occidentalis {Watson) Kinitzc. — Bushy samphire or kern greasewood is a shrubby evergreen bush i to 4 feet high with numerous cylindrical, jointed, fleshy, practically leaf- less alternating branches. The leaves are triangular or scale-like in shape. It has a large taproot and but few lateral roots. Generally found in low-lying moist lands from the 40th parallel southward, the northern plants DESCRIPTION OF ALKALI IXDICAILXO I'LAXTS 75 generally being somewhat more dwarfed than those farther southward. Aricmcsia spincsccns {Eat). — Bud brush has the woolly covering and the general appearance of common sagebrush, but is dwarfed — 4 to 16 inches high — and is spiny. Found throughout the West. Aslcr angustus. — Perennial herb with stems 4 to 12 inches high, branching, leafy. It has the typical aster design of flowers, but they are smaller with the corolla of the ray flowers reduced to the tube and much shorter than the elongated style. Aster paucijiorus. — Stems 8 to 10 inches liigh from a slender root-stock, single and bearing few heads. Leaves moderately fleshy and elongated in shape. Aslcr xylorliiza. — Perennial with deep-set woody roots supporting several or solitary stems. The heads are large with conspicuous white rays. Stems leafy, about 4 to 8 inches high, terminating in a short flower stalk. A triplex. — Salt-bush or shadscale {A triplex spp.), peren- nial and annual t^pes — perennial usually bushy or shrubby, and annual usually taller and more weed-like. Lea\'es generally alternate, simple, and often silvery or white scurfy or having an ashen-gray color. Bush is often mistaken for sagebrush, but several species have spines or thorns. Crcpis glauca. — Perennial herb with few small }-ellow flowers borne upon a leafless or practically leafless long stem. It is from 8 to 24 inches high and characterized by its covering of white powdery material on leaves and elsew'here and lack of pubescence. Chrysothamnus spp. - - Rabbit brush, or false golden-rod, are shrubby plants v.ith woody base on which shoots holding cylindrical, often hairy, but sometimes resinous 76 NATIVE VEGETATION AS AN INDICATOR leaves, are found. Clusters of yellowish flowers like those of golden-rod but lacking the ray-flowers around the margin of the clusters as in the golden-rod. The most notable alkali-loving species of this group is Chrysotliamnus lini- folius, which is found along wet banks of alkali streams; C. Wyomingesis and C. plattcnsis are found more on alkali plains. Cressa truxillensis. — A perennial herb with a woody base from which many leafy branches extend. The leaves are oblong or lance-shaped with very short stems, silky, hoary, or villous covering. It is found mostly near the seashore in Texas, but in California is found inland through- out the state, Distichlis spicata. — ■ Salt grass is the common salt grass of alkali soils. Dodccatheo7i salinum. — Shooting star or American cow- slip has a short crown from which spring numerous slender matted roots. Leaves about i inch in length, wide-spread- ing or ascending, smooth, and rather elliptic. Flowers borne upon a stem about 4 to 8 inches long are of a yel- lowish white with an indistinct purplish ring near the base and has segments of lilac-purple in places. Elymiis salinus {Jones) . ■ — Wild rye is a coarse perennial grass with flat rough leaves. It forms in dense bunches of rigid, wiry grass standing from i to 2 feet high. Found in Utah and Wyoming frequently in saline places. Flaveria angnstifolia. — This is a smooth-appearing herb with clusters of yellowish flowers and opposite stem- less leaves. It is 8 to 20 inches in height. Frankenia grandifoUa. — Alkali-heath is a perennial herb with a woody base and deep-rooted flexible, wiry, root-stocks. Numerous opposite or clustered simple rather thick, lance-shaped leaves from 3 to 6 inches long. Largely DESCRIPTION OF ALKALI-INDICATING PLANTS 77 confined to the Southwest as far north as Arizona and southern Nevada. Glaux marilima. — A salt marsh, small leafy-stemmed perennial herb propagated by slender running root-stocks. Stems about 2 to 4 inches high. Leaves oval-shaped. Flowers purplish or white. Halerpestes cymhalaria. — Trailing buttercup is so named because of long-jointed stolons from which spring new plants at each node. Low-growing, rather hairy, with yellow flowers and oblong cylindrical heads of fruit; found in moist places. Leaves broadly egg-shaped, coarsely toothed and clustered at the base of the flower stems or nodes of the stolons. Flower stem 2 to 4 inches high. Hemizonia pungens. — Spike-weed is a yellow-flowered much-branched spiny composite from a few inches to 2 or 3 feet high. The leaves are arranged opposite along hairy or bristly branches. Found in dense patches fre- quently to the exclusion of other plants on well-drained generally mildly alkali lands of southern California. Hordeum nodosum (L.). — Wild barley, sometimes called foxtail, belongs to the same group as common barley, but is seldom taller than 24 inches. Has a narrow spike which is usually dark green or purple, and is awnless. KocJiia. — White sage {Kochia vestita), dull gray plant about 5 to 6 inches high with a shrubby base and roundish densely hairy leaves. Viewed at a distance, bunches give appearance of gray blanket. Flowers solitary or few in the axils. Ovary oblong nearly equaling the calyx. Ripened ovary membranous. Strong taproot to about i foot deep. Lepidium montanum ( Nutt). — Pepper grass is a smooth appearing biennial herb with small white petals. The stems spring from the crown of the thick root and extend 78 NATIVE VEGETATION AS AN INDICATOR to a distance of 4 to 8 inches from the base. The leaves are toothed or have numerous leaflets along the main axis of the leaf. Myosurus apetalus {Gay) . — Mousetail is a very small annual herb with a tuft of spatulate entire leaves, with no apparent stem, surrounding a simple solitary live-petaled flower borne on a stem i to 2 inches high. It is found in wet saline places throughout the western states. Pluchea horealis. — Arrow, or irrigation, weed is a com- posite with a brushlike head supported on numerous hairy-covered, silvery, willow-like branches 4 to 8 inches high. Common along sandy or porous, deep, well-drained banks of streams or similar soils elsewhere. Pluchea camphor ata {L) DC. — Plowman's wort is a spicy, or salt marsh, Fleabane found in the marshes of Texas and Mexico. Pyrrocoma ( Null) . — Perennial herbs with alternate leaves and showy many-flowered heads of yellow flowers in the axils of the upper leaves or at the end of the branch. Plants generally from 4 to 8 inches high. Found through- out the Rocky Mountains. Salicornia spp. — Dwarf samphire is a low scaly-leafed but nearly leafless fleshy plant with cylindrical, many- jointed stems, and opposite branches. Frequent on saline land near lakes and ponds. Sarcohatus vermiculatiis. — Greasewood of inter- mountain country found on moist saline flats, patches of which generally appear a much brighter green than most saline vegetation except in fall when it changes to a yel- lowish color. Il» has numerous sharp spines at the base of which are small fleshy leaves with a bitter salty taste. It is a rigidly branched shrub about 2 to 8 feet high with a smooth whitish bark. DESCRIPTION OF ALKALI-INDICATING PLANTS 79 Scirpus spp. — Ruslics arc tufted plants with creeping root-stocks, the stem sheathed or leafy at the base and the spikelets in lateral cluster. Saline soils growing these plants are generally irreclaimable without considerable expense. Spartina gracilis. — Marsh grass is a perennial with simple and rigid slender reed-like stems coming from ex- tensively creeping scaly root-stocks. Stems generally 8 to 23 inches high and somewhat taller than the spreading, two-ranked, rough, and rigid leaves at its base. Spikes 4 to 10, mostly sessile, closely appressed to the nearly smooth rachis. Sporoholus airoides. — Tussock or dropseed, or purple top grass, has a stout coarse and rigid base or trunk often 18 to 20 inches high. The tufts of grass are often i to 3 feet in height. Open, feathery, pyramidal panicles with a purplish tinge in late summer are borne from the base trunk. Leaves smooth beneath but harsh above and taper gradually from base to a fine point somewhat rolled in- wardly at the end. Suaeda spp. — Inkweed, or saltwort, perennial shrub, with small, fleshy, stem-like leaves. Growing plants generally i to 2 feet in height but the dark-colored brush left when the plant ceases growth in the winter lies close to the surface of the ground. Triglochin maritima. — Arrow grass gives the appear- ance of an arrow because of a naked jointless stem bearing an arrowhead shaped greenish flower and having cylindri- cal rush-like leaves at the base which are shorter than the flower stem. About i to 3 feet in height and rather stout appearing. T. palustris similar to above but seldom reaches a height greater than i foot and the basal leaves are narrower than 2 mm., while leaves of above are from 2 to 4 mm. wide. 80 NATIVE VEGETATION AS AN INDICATOR Valeriana Jurjurescens {Nds.). — -The roots of this plant are slender and peculiarly scented, leaves entire, flowers minute and numerous with greem'sh yellow corolla. Fruit hairless, rough, and scaly. Found mostly in saline meadow lands. REFERENCES 1. Davy, J. B. Investigations on the Native Vegetation of Alkali Land;-. Cal. Sta. Rpt. 1895-97, pp. 53-75. 2. HiLGARD, E. W. Soils, pp. 527-549. (New York, 1906.) 3. Jensen, C. A., and Strahorn, A. T. Soil Survey of the Bear River Area, Utah. U. S. D. A. Bur. Soils, Field Oper. 1904, p. 27. 4. Kearney, T. H., Briggs, L. J., Shantz, H. L., McLane, J. W., and PiEMERSEL, R. L. Indicator Significance of Native Vegetation in Tooele Valley, Utah. Jour. Agr. Res. Vol. i (1914), pp. 365-417. 5. Mackie, W. W. Reclamation of White-ash Lands Affected with Alkali at Fresno, California. U. S. D. A. Bur. Soils, Bui. 42 (1907), pp. 45- 47- 6. Myers, H. C. Alkali Lands and Sugar-beet Culture. Jour. Soc. Chem. Ind. 22 (1903), pp. 782-785. Also consult standard books on Botany. CHAPTER VII CHEMICAL METHODS OF DETERMINING ALKALI TiiJiRE are so many distinctly different methcxis of making chemical analyses of soils that it is \ery difficult , to compare the work of the various investigators who have studied alkali under field conditions. The wide variations so often noted between results of investigators in different places may be accounted for in part by the differences in methods of determining the quantity of alkali present. It is necessary that the method used be known before in- telligent interpretation of analyses can be made. In the interest of uniformity it would be highly desirable to adopt standard methods. Before this can be done, it will be necessary to make a careful study of the various methods in order that the best one to secure uniformly accurate results may be chosen. Preparing the Solution. — Probably the greatest varia- tion in methods of analyzing alkali soil is found in making the soil extract. The soluble salts are dissolved with water and not with the stronger dissolving agents that are used in making a complete analysis of a soil, since it is the water-soluble salts that come under the designation of alkali. The principal variation in methods consists in the relative quantities of water and soil used, the time of agitation, the time allowed for settling, and the method of filtering. There are certain other methods, such as ex- 8i 82 METHODS OF DETERMINING ALKALI trading the solutions with oil or by pressure or centrif- ugal force, which are not in general use as yet, the great drawback being that little more than the free water can be obtained. King and his associates in their studies of soil nitrates used a method which, with a number of amendments, has been used extensively by later investigators, Schreiner and Failyer (9) describe a modification of this method which has probably been used more widely than any other. They discuss it as follows: "If comparable results are to be obtained, it is essential in preparing the soil extract to follow as nearly as practical* a uniform procedure. The volume of water used and the time of its action are necessarily conventional. The ratio of five parts of water to one part of soil has been adopted in procuring solutions of the readily water-soluble salts in many of the soil studies. The mixture is agitated three minutes and allowed to stand twenty minutes before filtering. The exact procedure when the soil to be ex- amined is still in the moist state as collected in the field varies slightly from that when it is air-dried or oven- dried. All results, however, are stated on a uniform basis, preferably on the dry soil. The results from a moist soil are not comparable with those obtained from a dried soil, although both be stated in terms of dry soil, owing to the fact that dried soils give a somewhat greater concentra- tion of soluble salts in the soil extract. "From Moist SoiL — The moist samples taken from typical and comparable portions of the field are well broken up and mixed in a granite- ware basin or porcelain dish. Two 100-gram portions of this composite are then weighed out on a balance capable of weighing accurately to within 0.1 gram. One of these portions is for the moisture de- FROM MOIST SOIL 83 termination. It is thorough I}- chicd in an o\cn and the content of moisture thus obtained taken into consideration, if the results of the analyses of the solution are to be ex- pressed in terms of the dry soil. The calculation to parts per million of dry soil is readily made by means of the following formula: 5(500 + W) s = (100 - W)' where S is the parts per million of the dry soil, 5 the parts per million of the soil solution as found by analysis, and W is the amount of moisture in grams, in the 100 grams of the moist soil sample used in making the solution as described below. If it should be desired to calculate the strength in parts per million of the actual soil moisture as found in the above moisture determination, the following formula is applied: 5(500 -f W) M = W where M is the parts per million of the soil moisture, 5 and W as in the previous formula. "Measure out 500 cc. of water, and after transferring the other 100-gram portion of the moist soil to a mortar add enough of the water to make a thick paste, working well with the pestle so as to break down all granulations and to have the soil well puddled. The balance of the 500 cc. of water is then added and the mixture well stirred with the pestle during three minutes. If more samples are to be worked in the mortar, the mixture is transferred to a jar and is allowed to stand twenty minutes, during which the coarser particles settle. The supernatant turbid liquid is then poured into one of the filtering cham- 84 METHODS OF DETERMINING ALKALI bers fitted up with a well-washed Pasteur-Chamberland filter tube. *' From Dry Soil. — If the soil sample to be used is al- ready air-dry and it is desired to give the results in terms of the completely dried soil, it will be necessary to de- termine the amount of moisture still present by heating a loo-gram portion in the drying oven and making the proper allowance in the final calculation, using the formula given above. If the soil to be examined is oven-dried the whole composite is removed from the oven while hot and pulverized in a large mortar, screening through a 2-mm. seive. A loo-gram sample is then weighed out and poured into a glass-stoppered bottle. Add 500 cc. of distilled water to the soil in the bottle and shake vigor- ously for three minutes to insure a thorough puddling of the soil particles. The mixture is allowed to stand twenty minutes for the coarser particles to subside and is then filtered. The mortar may be used as described above, but it is more convenient to use the shaking bottle when working with dry pulverulent soils." Methods differing from the above for extracting soil solutions, as summarized by Hare (7) are: the Arizona method in which 50 grams of soil are added to 8oo cc. of water and heated on a water bath for 10 hours when enough water is added to make the solution up to 1000 cc. and the solution allowed to stand over night before being filtered; the California method in which 150 grams of soil are added to 300 cc. of water and after shaking allowed to stand 12 hours; the Montana method in which 50 grams of soil are added to 500 cc. of water, shaken and allowed to stand over night; the Texas method in which 200 grams of soil are added to 1000 parts of water and shaken oc- casionally for 2 hours; and the Utah methods, in the COMPARISON OF RESULTS 85 Ti"^ O 1- o CO -t M NO p t-5 c o M n lo o o 1^ Tt- CO NO O ,^ c_; 00 M ro fs o o ^.a y, • in .— 4j t -~^ a 'o ,^ o o [^ t^ OJ C _c Perc of Arizfi Metl t^ M ri >n d -+ -^ CO • 1^ O^ w "-> o M On 0> '-' M •^ ■V M O - i -= 2 r. T^ <* NO -^ M ON O c-j M 8 00 o M CO O "* Jr cent of rizona lethod 1 >0 N CO M O d lO o o ■* t^ lO I^ OO CO 't o t^ o- 6 <-* M few 1 exico :thod -J- l^ ,^ Cl StJ lO H-t 'T o o lO NO (N ^ Hjs CO ' '~^ 1 il M o !>• CO l^'o|'^ O ^ ^ ro d (li 0 w On Tt M On rrj NO c^ -^ O ro O IN O PJ NO o o o (N U 3 iJ ^£S CO :r cent of rizona lethod lo O •* NO o NO On O r^ t^ ro ^o o J^ CO O \0 00 t^ CO o NO 00 On ^ <-* tH i 2 lO O «o o o CO lO 00 CO M 00 M o>i; lO M « o o o t>» c< o CO g S"? O t^ t^ M o CO ON '^ S-3|-S »o O lo M d M r^ 00 O On O O o CO O CO £ o lO IT) tH . - t/3 u ■ - t/) >H t« . 4J a rt c aj y 1) c z u ;?; o 1 o .0 c ■h ^1. >, OJ r2 'e "o "o , *J •-< - "o Ul S s5c5 t« c c 6 CAl s sio" 4; ^■O G — U *^'2 o — < u ^:2 o — u a 3 sl ^J^J" -3 c"S iH rt d —; C !- "-1 rt c^ rt S o o ^2 a=^ z rt ' materially afYect the absorption of irrigation and rain water in practice. Where gypsum is present in large quantities in an ir- rigated soil, it is gradually washed out, causing the soil to 130 RELATION TO PHYSICAL CONDITIONS sink and leave typical holes. Sodium and magnesium chlorides and sulphates have less marked, but very dis- tinct, effects on moisture movements. Evaporation of Moisture. — The vapor tension of water is reduced by the presence of dissolved salts; hence the presence of alkali reduces the rate of evaporation. The rate of decrease of evaporation produced by the various salts is shown by Briggs (3) and by Harris and Robin- son (11). It is not equal to the reduction in the vapor tension of the solution since the air at all times contains some moisture. The results of Harris and Robinson showed an evaporation of 190 grams from distilled water and only 100 grams from an equal surface of water in which had been dissolved 30 per cent of sodium chloride. Sand moistened with distilled water had a loss of 80 grams, whereas that with a 2-normal solution of sodium nitrate evaporated but 53 grams of water. In an experiment by the author a loam soil, to which had been added various quantities of the sodium chloride, sodium sulphate, and sodium carbonate, was placed in petri dishes in a closed chamber in which the air was kept saturated. The soils all took moisture from the air, the rate of absorption depending on the salt and the concen- tration. In the higher concentrations so much moisture was absorbed that free water covered the surface of the soil. A condition similar to this is often found in nature where the soil of an alkali spot is wet constantly during the season even though the surrounding soil is dry. REFERENCES , I. Bemmeln, J. M. VON. On the Plasticity of Clay Soils. Chem. Weekbl. 7 (1910), pp. 793-805. 2. Breazeale, J. F. Formation of Black Alkali (Sodium Carbonate) in Calcareous Soils. Jour. Agr. Rsch. 10 (1917), PP- 541-589- REFERENCES 131 3. Briogs, L. J. Salts as liilluL-m in^' tlu' Kale of I'>vai)<>ration of water from Soils. U. S. I). A. Hur. of Soils, Kpt. 64 (iSqi)), pp. 184-198. 4. Brioc.s, L. J., and Lapham, M. II. Inlhicncc of Dissolved Salts on the Caiiillary Rise of Soil Water. U. S. I). A. Hur. Soils, Ikil. 19 (1902), 18 pp. 5. Cameron, F. K. Application of the Theory of Solution to the Study of Soils. U. S. D. A. Bur. Soils, Rpt. 64 (1899), pp. 141-172. 6. Davis, R. O. E. The Effect of Soluble Salts on the Physical Properties of Soils. U. S. D. A. Bur. Soils, Bui. 82 (191 1), 38 pp. 7. Free, E. E. The Phenomena of Flocculation and Deflocculation. Jour. Franklin Inst. 169 (1910), pp. 421-438, and 170 (1911), pp. 46- 57- 8. Gardner, F. D., and Stewart, John. A Soil Survey of Salt Lake Valley, Utah. U. S. D. A. Bur. of Soils, Rpt. 64 (1899), pp. 77-114. 9. Gedroits, K. K. Colloid Chemistry in the Study of Soils. Zhur. Opytn. Agron. (Russ. Jour. Exp. Landw.), 13 (1912), pp. 363-420. (Abs. E. S. R. 28, p. 516.) 10. Hall, A. D. Some Secondary Action of Manures upon the Soil, Jour. Roy. Agr. Soc. (England), 70 (1909), pp. 12-35. (Abs. E..S. R. 23, p. 320.) 11. Harris, F. S., and Robinson, J. S. Factors afTecting the Evaporation of Moisture from the Soil. Jour. Agr. Rsch. 7 (1916), pp. 439-461. 12. Heileman, W. H. Alkali and Alkali Soils. Wash. Sta. Bui. 49 (1901), 35 PP- 13. HiLGARD, E. W. Soils, pp. 183-187. (New York, 1906.) 14. Kellerman, K. F. The Relation of Colloidal Silica to Certain Im- permeable Soils. Sci. n. ser. 33 (191 1), pp. 189-190. 15. LouGHRiDGE, R. H. Investigations in Soil Physics. Cal. Sta. Rpt. 1893-94, pp. 70-100. 16. Masoni, G. The Flocculating Power of Some Soluble Salts on Clay Substances of the Soil. Spaz. Sper. Agr. Ital. 45 (1912), pp. 113- 159. (Abs. E. S. R. 27, p. 620.) 17. Sacchase, R., and Becker, A. The Influence of Lime and Salts, as well as Certain Acids, on the Flocculation of Clay. Landw. vers. Stat. 43 (1893), pp. 15-25- (Abs. E. S. R. 5, p. 696.) 18. Sharp, L. T. Fundamental Relationships between Certain Soluble Salts and Soil Colloids. Univ. Cal. Pub. .Agr. Sci. i (igi6), No. 10, pp. 291-339; also see Proc. Nat. Acad. Sci. i (1913), pp. 563-568. CHAPTER X RELATION OF ALKALI TO BIOLOGICAL CONDITIONS IN THE SOIL The effect of soil alkali in reducing the growth of crops or in changing completely the type of native vegetation is easily recognized. There are, however, equally as im- portant changes produced in the microorganisms. These changes cannot be detected without special study of a technical nature and are therefore not so well understood. The micro-flora of the soil is probably as varied and as complex as the plant growth on the surface, but the re- sponse of these smaller organisms has not been as thoroughly studied as that of the higher plants. However, a few rather definite facts have been estabhshed. Relation of Soil Organisms to Fertility. — It has long been known that bacteria and fungi in the soil are essential to continued growth of the higher plants. The constant tearing down of dead organic matter furnishes new material for assimilation by living plants. Most plants require nitrogen in the form of either ammonium salts or nitrate nitrogen. One of the important sources of such salts is vegetable matter of the soil which has been reduced to the proper form by decomposition. Certain microorgan- isms attack and break up the complex organic tissues of plants as soon as their resistance has been decreased by death or otherwise. Different organisms act on the dif- ferent compounds as decomposition proceeds until the material is finally reduced to the simple compounds such 132 SOIL STERILITY 133 as are required by plants. Fungi and putrefying bacteria reduce the vegetable proteins to a form which can be acted upon by the ammonifying bacteria which finally leave the nitrogen in the form of ammonia; it may then be either combined into an ammonium salt and utilized by the plant or oxidized by other organisms into nitrous, and then nitric, acid. The latter combines with bases in the soil to form nitrates. Where the proper organisms are in the soil in sufficient numbers to carry this process smoothly to a finish the soil is usually highly productive. Desirable organisms other than of the class mentioned above are the symbiotic nitrogen-fixing bacteria which Vive in the nodules of legume roots and synthesize at- mospheric nitrogen into forms which can be utilized by the host plant. A number of diflferent kinds of bacteria fix atmospheric nitrogen without symbiosis with higher plants; still other organisms are known to break up and make available certain insoluble compounds in the soil which are essential to profitable crop production. The desirable microorganisms do best under practically the same soil conditions as do crop plants. They thrive or grow most luxuriantly in soils rich in organic matter, well aerated, and with about the optimum moisture content for most crops. Where the soil is water-logged, puddled, or contains injurious matter, the more desirable nitrify- ing and nitrogen-fixing bacteria are largely replaced by denitrifying and putrefying organisms which rapidly deplete the soil of available nitrogen. Biological Inactivity and Soil Sterility. — Alkali salts which injure or prevent the production of crops on certain lands also injure the activities of the desirable soil organ- isms. Taylor (i8) found that at least part of the sterility of certain Bengal soils was due to scarcity of bacteria and 134 BIOLOGICAL CONDITIONS OF THE SOIL nitrogen. Some soil students go so far as to say that an important part of the injury to crop production on alkali lands is due to decreased bacterial activity. They hold that this is shown by the fact that crop yields do not always decrease to the full extent when alkali is first brought in contact with the soil, but continue to decrease as time allows the microorganisms to die gradually. They also point out that soils do not become at once productive after being drained of alkali, but gradually increase in productive- ness as the desirable organisms are given time to multiply. Whether the changes which soils undergo subsequent to drainage are due largely to bacterial activities or almost wholly to physiological changes is not at present known. From preliminary experiments by Lipman and Fowler (13) in which soils were treated with 500 parts per million of sodium carbonate, 1000 parts per million of sodium chloride, 2500 parts per milhon of sodium sulphate and mixed salts, and then leached free of the salts, it was found that nitrification was affected profoundly by the leaching. The characteristic effects of the salts on the organisms remained after the salts had been almost en- tirely leached out. The soil receiving the mLxed salts was most toxic, with sodium carbonate, sodium chloride, and sodium sulphate in the order named. This same action was noted for the nitrogen-iixing bacteria, although it was not so characteristic as with the nitrifying ones. The results with the ammonifiers was not so distinctive. Barnes and Ali (i) found that the ammonifying bac- teria, and to a less extent the nitrifiers, might be used to measure the toxicity of the alkali or its crop-producing power much more quickly and at less expense than by growing crops. They believe that the alkah merely causes the organism to lie dormant until favorable conditions LIMITS OF TOXICITY \^5 again prevail. By determining the ammonifying, nitrify- ing, and nitrogen-fixing power of the organisms they pro- pose to classify land that is being drained as to its ability to grow crops. Concentrations of Alkali which Limit Biological Ac- tivities. — The quantity of alkaU that will cause injury to the ammonifjing and nitrifying bacteria as determined by different investigators varies from a minimum of 250 parts per million of sodium carbonate, which was found by Lipman (10) to inhibit growth of these organisms, to a maximum of 4000 parts per million of this salt as found by Kelley (8) . The nature and concentration of the nitrog- enous material used to determine the activity of the or- ganisms has been found to make a great difference in the rate of nitrification. Kelley found that where i per cent of dried blood was used as the nitrogenous material, 500 parts per million of sodium carbonate was distinctly toxic, but where only 0,1 per cent of dried blood was used the organisms were apparently not affected by the presence of 4000 parts per million of sodium carbonate. He also found that while 1000 parts per million of sodium car- bonate were toxic to nitrification in the presence of 0.15 per cent of ammonium sulphate, this concentration was markedly stimulating in the presence of 0.0625 per cent of ammonium sulphate. The large discrepancies in the quantities of alkali which these bacteria withstand are probabl}' due in part to the differing quantities and kinds of nitrifying materials used as well as the kind and dif- fering natures of the soils. Dried blood, cottonseed meal, ammonium sulphate, and numerous other materials have been used; this makes comparisons of the different ex- periments diflficult. Standard methods are needed in this regard as they are in other alkali work. It is probable 136 BIOLOGICAL CONDITIONS OF THE SOIL that absorption of the sodium carbonate by the organic matter of the soil plays a considerable part in these ex- periments, as the salts were added to the soil, and, as mentioned in Chapter V, loam soils, especially those high in organic matter, do not hold in solution all of the sodium carbonate added. The various experiments agree pretty well that about looo parts per million of sodium chloride is a toxic quantity. Greaves, Carter, and Goldthorpe (6) found a stimulation with this salt up to a concentration of about looo parts per million above which there was a marked toxicity Other investigators have found stimulation where the quantities of sodium chloride were lower than this. From the available experiments, the toxic limits of sodium sulphate appear to lie between 2500 and 5000 parts per million. Small quantities of this salt were found to be stimulating to nitrifying bacteria by Brown and Hitchcock (2), but Greaves and his associates (6) found no stimulation even in soils containing very small quanti- ties of sodium sulphate. Greaves found the toxic limits for sodium nitrate to be only a little greater than 200 parts per million, or much more toxic in comparison with its toxicity to wheat than are the other sodium salts. The quantities of sodium carbonate, sodium chloride, and sodium sulphate present in soils producing half the quantity of dry matter of normal wheat plants and those in soils producing half-normal nitrification were found to be nearly the same. The salts which stimulated wheat most also stimulated nitri- fying bacteria. From the low quantities of sodium carbonate and sodium nitrate which cause injury to nitrifying bacteria, it appears that the puddling effect of these salts may play an im- LIMITS OF TOXICITY 137 portant part in their toxicity. In Colorado (17), however, soils containing rather large quantities of nitrates were found to be still active in nitrif)ing, although when the nitrates became excessive the organisms were destroyed or greatly checked in their activity. Kelley (8) found that the nitrite-forming organisms were still active in soil containing so much alkali that nitrate formation had practically ceased. Nitrogen-fixing organisms were found by Lipman and Sharp (14) to be inhibited by the presence of 4000 to 5000 parts per million of sodium carbonate. The toxic limits for sodium chloride were 5000 to 6000 parts per million, and for sulphate about 12,500 parts per million. Much smaller quantities were found injurious where the soil was leached of its salts, the quantity in this experiment being nearly the same as with the nitrifying bacteria (13). Hills (7) reports that 1500 parts per million of sodium nitrate stopped multiplication and probably killed many of the nitrogen-assimilating organisms. Symbiotic bac- teria (15) on peas were retarded in their activities when sodium salts in cultural solutions with a strength of ;^t,^t, parts per million were used. Alkaline nitrates at a con- centration of 100 parts per million and ammonium salts at a concentration of 500 parts per million checked the production of root tubercles. Ammonification organisms have been found by investi- gators who have experimented with them in comparison with those concerned with nitrification and nitrogen- fixation to be more tolerant of alkali than these other nitrogen-working organisms. Lipman found the toxic points for ammonification to be at 20,000 parts per million of sodium carbonate, 1000 to 2000 parts per million of sodium chloride, and 4000 parts per million 138 BIOLOGICAL CONDITIONS OF THE SOIL of sodium sulphate. For one-half normal ammonifying power, Greaves found the points to be at ii,66o parts per million of sodium carbonate, 1170 parts per million of sodium chloride, and 8520 parts per miUion of sodium sulphate. The results of Brown and Johnson (3) indicate a lower limit, but all show that sodium chloride is the most toxic. The relationship of the three salts is nearly re- versed to that in their action on plants. Greaves (5) found sodium nitrate to be toxic at about 426 parts per million. He noticed a stimulating effect of sodium carbonate, sodium nitrate, and sodium chloride in decreasing order when only small quantities of these salts were present, but found none with sodium sulphate. His experiment also showed that some salts increase in toxicity with in- creasing quantities of salts much faster than others. Lipman (9) noticed antagonism between the anions of the sodium salts, the action being strongest betweeji 7000 parts per million sodium carbonate and 2000 parts per milHon sodium chloride, next between sodium carbonate and sodium sulphate, and weakest between sodium chlo- ride and sodium sulphate. Antagonism was noted '^ be- tween toxic and stimulating salts as well as between two toxic salts." A reduction of the stimulating effect of sodium carbonate on ammonification was noticed by Brown and Johnson (3) when calcium carbonate was added to the soil, but the toxic effect was also reduced. Both sodium chloride and sodium sulphate showed more stimu- lation and certain toxic quantities became stimulating when calcium carbonate was added. "Combinations of various salts in non-toxic individual amounts in the pres- ence of calcium carbonate became toxic to ammonification." Other soil organisms have been little studied. Hun- ter's (16) experiments show that Actinomycetes were REFERENCES 139 stimulated by the addition of 50,000 parts per million of potassium chloride or sodium chloride, but that spore formation was decreased, while 100,000 parts per million usually arrested development. REFERENCES 1. Barnes, J. H., and Ali, Barkat. Alkali Soils: Some Biochemical Factors in their Reclamation. Agr. Jour. India, 12 (1917), pp. 368- 389.. (Abs. E. S. R. 38, p. 815.) 2. Brown, P. E., and Hitchcock, E. B. The Effects of Alkali Salts on Nitrification. Soil Sci. 4 (1917), pp. 207-229. 3. Brown, P. E., and Johnson, D. R. Effects of Certain Alkali Salts on Nitrification. Iowa Sta. Res. Bui. 44 (1918), 24 pp. 4. Greaves, J. E. Azofication. Soil Sci. 6 (1918), pp. 163-217. 5. Greaves, J. E. The Influence of Salts on the Bacterial Activities of the Soil. Soil Sci. 2 (1916), pp. 443-480. 6. Greaves, J. E., C.a.rter, E. G., and Goldthorpe, H. C. Influence of Salts on the Nitric-nitrogen Assimilation. Jour. Agr. Res. 16 (1919), pp. 107-135. 7. Hills, T. L. Influence of Nitrates on Nitrogen Assimilation. Jour. Agr. Res. 12 (1918), pp. 183-230. 8. Kelley, W. p. Nitrification in Semiarid Soils. Jour. Agr. Res. 7 (1910), pp. 417-437- 9. LiPMAN, C. B. Antagonism between Anions as Affecting Ammoni- fication in Soils. Centbl. f. Bakt. Abt. 2, Bd. 36 (1913), pp. 382- 394- 10. LiPMAN, C. B. To.xic Effects of Alkali Salts in Soils on Soil Bacteria. II. Nitrification. Centbl. 1. Bakt. Abt. 2, Bd. 3,3 (1912), PP- 305-313- 11. LiPMAN, C. B. To.xic Effects of .\lkali Salts on Soil Bacteria. I. Am- monification. Centbl. f. Bakt. Abt. 2, Bd. 32 (1911), pp. 58-64. 12. LiPMAN, C. B., Burgess, P. S., and Klein, M. A. Comparison of the Nitrifying Powers of Some Humid and Some Arid Soils. Jour. Agr. Res. 7 (1916), pp. 47-82. 13. LiPMAN, C. B., and Fowler, T. W. Preliminary Experiments of Some Effects of Leaching on Soil Flora. Soil Sci. i (1916), pp. 291-297. 14. LiPMAN, C. B., and Sharp, L. T. Toxic Effects of Alkali Salts in Soils on Soil Bacteria. III. Nitrogen Fixation. Centbl. f. Bakt. Abt. 2, Bd. 35 (1912), pp. 647-655. 140 BIOLOGICAL CONDITIONS OF THE SOIL 15. Marchal, E. Influence of Mineral Salts on the Production of Tuber- cles on Pea Roots. Compt. Rend. Acad. Sci. (Paris), 133 (1901), pp. 1032-1033. (Abs. E. S. R. 13, p. 1017.) 16. MuNTER, E. The Influence of Inorganic Salts on the Development of Actinomycetes, III. Centbl. f. Bakt. 2 Abt. Bd. 44 (1916). pp. 673- 695- 17. Sackett, W. G. Bacteriological Studies of the Fixation of the Nitro- gen in Certain Colorado Soils. Colo. Sta. Bui. 179 (191 1). 18. Taylor, C. S. Effect of Salts on Soils. Dept. Agr. (Bengal), Quart. Jour. 2 (1909), pp. 281-287. (Abs. E. S. R. 22, p. 124.) CHAPTER XI MOVEMENT OF SOLUBLE SALTS THROUGH THE SOIL The greatest problem connected with the utilization of alkali lands is control of the movement of soluble salts. Were it possible to handle the land economically so that the movement of the alkali would be continually down- ward into the subsoil, or better, into the drainage system where it would be permanently removed from the feeding zone of the plants, the alkali problem would be solved. The upward translocation of enormous quantities of soluble salts into the top foot or two of soil has ruined vast areas of the most productive lands of the arid regions. Salts in Natural Soils. — Where undisturbed by flooding and where the water-table is a considerable distance be- low the surface, soluble salts tend to accumulate at some distance beneath, rather than at the surface of arid soils. The rainfall is light and frequently so distributed that the moisture penetrates to a distance of only 3 to 4 feet in most soils. Much of the water that enters the soil is needed by the plants growing upon it and this water is extracted some distance below the surface. A large part of the movement of salts is in connection with capillary action, and because the capillary movement of moisture to the surface of the soil is reduced by the rapid drying out of the surface soil, little of the water is allowed to evaporate at the surface and deposit its soluble salts. Since there is little movement of water except through 141 142 MOVEMENT OF SOLUBLE SALTS roots ill deep arid soils, and since the first flush of water passing through a soil usually carries considerably more salts than the subsequent water, the usual movement of alkali under natural conditions is toward the lower point of rain penetration. In sandy soils or in regions where the rainfall is greater, the penetration of the water is greater than on the more impervious soils or where the rainfall is light, and the accumulation of the salts at dif- ferent depths varies accordingly. It was found in Cali- fornia (i6) that on a sandy loam soil with a rainfall of 8 inches the greatest accumulation of salts was at a depth of 3 to 4 feet, whereas in a coarse sandy soil in the same place the depth of greatest salts was below 4 feet. Where the rainfall was only 3 inches the maximum salt was at about 18 inches in a sandy loam soil, whereas with 15 inches the bulk of the salts was at 5 feet. Salt Movement with Water. — When these arid lands are brought under irrigation, however, this balanced con- dition is frequently upset. The soil is kept so much more moist that capillary action is much easier, and not infrequently seepage and over-irrigation raise the water- table so high that upward movement is possible from the free water in the soil. Under such conditions, the alkali accumulations of the lower depths are moved to the upper zone of soil where they become of greatest injury to plants. It is in this manner that many of the formerly productive irrigated lands have been rendered useless. Diffusion of the salts in the soil plays a local part in the movement of alkali, but, according to the laboratory work of McCool and Millar (23) and others, diffusion causes changes for only a few inches about concentrated salt solutions, and the field observations of Mackie (24), Headden (14), Hansen (7), and others show that because SALT MOVEMENT WITH WATER 143 of the dilTcrences in the character and concentration of alkali in short distances vertically or horizontally, there must be movement of water before significant mo\'ements of salts are possible. The extent to which salts mo\-e with water passing through a soil has been studied by a number of investi- •-«S' r Fig. 17. — Cultivated Land that had to be Abandoned BECAUSE OF THE RiSE OF AlKALI. gators. In laboratory experiments, with alkali soils kept so continually moist that there was constant water move- ment, the author (9) has shown that alkali, principally sodium chloride, is very readily transported from one por- tion of the soil to another, either upward or horizontally. The salts became very concentrated in the upper inch or two of soil where the water was allowed to evaporate. The first water percolating through alkali soil contained several times as much salts as was found later. Tulay- kov (30) found salts moved gradually and more or less 144 MOVEMENT OF SOLUBLE SALTS completely to the surface of a column of soil 150 cm. in height supplied with water at the bottom. Hilgard as well as Puchner (28) and others have noted a migration of salts upward and dowaiward as the moisture changed places. The latter experimenter, using quartz sand, loam, and rich humus soils, found the movement to depend somewhat on the chemical and physical properties of the soils. Powdery soils allowed the salts to move more readily than crumbly soils. Kossovich (20) reports a greater movement on a loess clayey soil than on a sandy soil and that sodium chloride hastened the rise of water while sodium carbonate impeded it. It is probable that the differences both in nature of the salts and their con- centration so often noticed in fields containing alkali are, in part at least, due to changes in the nature of the soils which in turn modify the rate of capillary action. In studies of the movement of moisture, Briggs and Lapham (2) conclude that "concentrated or saturated, solutions of all salts materially diminish capillary action," but that in dilute solutions the neutral salts had very little influence on capillary action. They found sodium carbonate to have a greater influence on capillarity than the neutral salts. The extent of the fluctuation of salts upward and down- ward under irrigation in the field has not been determined with any degree of accuracy. Hilgard considered the movement to be mostly in the top four feet. Considering the ease with which the salts move with the water and from observations of the movement of soluble salts with irrigation water when no alkali was present (11), it is very probable that the salts are frequently moved to great depths where not prevented by impervious soils or by a water-table. Investigations show that water is seldom EFFECT OF WATER-TABLE 145 drawn to the surface by capillary action from a depth greater than 2 or 3 feet, so that the greater part of the alkali which penetrates beyond this depth never again reappears at the surface unless the water-table rises to within a few feet of the surface. Water movement below the top 2 or 3 feet is probably caused by moisture removed by the plants or by the action of gravity so that it is improbable that there is such movement of salts other than local diffusion and movement with the gravitational, or free, water. Effect of Water-table. — Where the drainage is poor so that there is a rise of the water-table the conditions are modified accordingly. With a water-table near the sur- face, the soluble salts dissolved from the soil by down- ward movement are held where they may be drawn by capillarity to the surface and again accumulate. Head- den (14) observed that the, water in shallow wells rose in salt content from 2871 parts per million before an irriga- tion to 4444 parts per million twelve days following and then gradually fell to 2590 parts per million just before the next irrigation. He and also IMackie (24) noticed that the concentra- tion of the top of the water-table was greater than the lower depths and that there was a rather gradual de- cline in the soluble salts in the water with depth. As the water-table rises the most concentrated solutions are presented for upward translocation. Headden (14) made a rather detailed study of the effect of seasonal movement of water-tables from which he concluded that as the water fell much of the salts in the free water was retained by the soil so that the free water gradually became weaker as it sank and again increased as it rose. He (15) found that the kind and quantity of salts in the soil solution differed markedly from those found in the free ground water or 146 MOVEMENT OF SOLUBLE SALTS from the alkali incrustations on top of alkali soil. Certain of the soluble salts were absorbed by the soil, while others moved somewhat more freely. Calcium sulphate was the most abundant salt in the soil solution with magnesium sulphate second, while sodium sulphate formed consider- able of the efflorescent matter on the surface, and the salts next the surface. Sodium chloride did not separate as readily as some of the other salts. Very little calcium sulphate left the soil to form part of the incrustation. Movement of Various Salts. — It has been noticed by numerous observers that the different salts move some- what independent of each other so that in comparatively short distances either vertically or horizontally rather marked differences are found. Experimenters have come to varying conclusions as to the ease of movement of the different alkali salts. Practically all field investigations have shown that the chlorides are the most sensitive to water movement. Both under arid alkali soils and where irrigation has shifted the salts to other positions, sodium chloride is generally found in its highest concentration at the point where the total salts are highest. Headden (12, 13) states that while retention of salts differs with the soil, sodium sulphate was most markedly retained, sodium chloride slightly, and sodium carbonate hardly at all, and that "there is a tendency for the 'white alkali' to pass into the deeper seated waters" and out of the region where there is good drainage. King (18) reports sodium sulphate as being readily absorbed by the soil, while sodium chloride was not retained. The soil has a slight retentive power for the acid radical of sulphates but none for nitrates, chlorides, nor carbonates according to Waring- ton (32). Dimo (4) noticed accumulations of sodium chloride and sodium sulphate at a depth of 50 cm. in a MOVEMENT OF VARIOUS SALTS 147 field soil, while in the deeper la}eis sodium bicarbonate and sodium carbonate gradually replaced the former salts. The work of Mackie (24) in California indicated that sodium carbonate was readily absoibed by the soils and therefore held its position in the soil well. On irrigated soils he usually found sodium carbonate in the greatest quantities near the surface, but on virgin soil its location varied in depth down to the hardpan. From results on f -_ - . - . .-.Hi Fig. 18. — Alkali Eating away the Fence Posts. land irrigated 4 or 5 years presented by Hilgard and Loughridge (16) it appears that sodium chloride moved upward to the first foot relatively faster than sodium sul- phate and considerably faster than sodium carbonate. Few data are at hand to show to what extent this dif- ference in the rate of movement of the different salts pro- ceeds under field conditions. Analyses of drainage water from alkali land near Salt Lake City, Utah, reported by Dorsey (6) show that in the course of three years the chloride was removed relatively faster than the other alkali salts when it constituted by far the greater part of 148 MOVEMENT OF SOLUBLE SALTS the alkali. Drainage of a soil in California (22) removed about 85 per cent of the sodium chloride, 83 per cent of the sodium sulphate; drainage and conversion to sulphate reduced the sodium carbonate content to 65 per cent of the original quantity. Rate of Alkali Movement. — Theoretically, the alkali salts are so soluble that their removal from the soil by drainage should take only a short time, but in practice it often takes several years to reduce the salt content of seriously affected alkali lands sufhciently to produce crops. Dorsey (5) attempts to explain the difficult move- ment by the theory that the salts from the descending free-water solution are drawn into the capillary spaces of the soil where rapid downward movement is prevented. Subsequent downw^ard percolation is attributed to dif- fusion of the salts outward into the free-water spaces. Warington (32) states that the first water percolating through land containing soluble salts at the surface was much more concentrated than subsequent leachings but that where the chloride was first incorporated in the soil and then leached its concentration in successive leachings gradually increased. He explains this by assuming that the first water that comes from a drain passes through cracks and burrows of insects and comes direct from the surface, while that passing through the soil spaces alone does not arrive until later. To explain the extremely slow movement of soil solu- tions through alkali soils, especially those under laboratory or other conditions where the alkali is added to the soil as a single salt, Sharp (29) offers the theory that the alkali salts react with the colloids of the soil causing diffusion. He found that where solutions of sodium chloride or- sodium sulphate were in constant contact with the soil the rate of RATE OF ALKALI MOVEMENT 149 percolation was increased, but that where soils treated with these salts were leached the rate of percolation was diminished. In one exj^eriment it was noticed that the quantity of suspended matter leached from soil containing sodium chloride was ten times that from the check and that the rate of percolation had been diminished to about one- tenth that of the check. It was further learned that once the sodium chloride was leached from the soil a larger quantity was required again to flocculate the soil and that it was more difficult thereafter to repair the deflocculated condition. A large number of investigators have noted an increase of calcium and magnesium and a decrease in sodium in alkali water after it had percolated through a soil. This exchange of bases is said by Sharp to result from displacement of calcium and magnesium by the sodium in the colloidal substances of the soil and the re- sulting increased diffusibility to be the cause of the retarded movement of the water. The removal of the calcium and magnesium from the soil is thought by him to be of less importance than the increased diffusibility of the colloids, although these bases are recognized as being important in the deflocculation of the colloids and in maintaining the proper physical properties of the soil. Contrary to Sharp's results, Pagnoul (26) did not find the sodium of sodium sulphate, nor to an appreciable extent sodium carbonate, to replace lime of the soil, and other experi- menters do not report sodium sulphate as replacing lime except v/here sodium chloride was also present. Pagnoul agrees with Sharp that lime replaces the bases of chlorides of potash, soda, and ammonia. If the degree of per- meability to water can be taken as a measure of the de- flocculation of soils, experiments by Beeson (i) show sodium chloride to be more than twice as powerful as 150 MOVEMENT OF SOLUBLE SALTS sodium carbonate as a deflocculating agent but less than one-half as powerful as sodium nitrate. Percolation was at the rate of 1.2 cc. per hour for soil containing 1886 parts per million of sodium chloride and at the rate of 4.1 cc. per hour for soil containing 11,457 parts per million of sodium sulphate, while that of the untreated soil was at the rate of 10.2 cc. per hour. Hare (8), however, found sodium chloride much easier to leach into the deeper layers of the soil than sodium sulphate and that the dif- ference was many times greater in an adobe soil than in a sandy loam. It was with great difficulty that the sodium sulphate was leached downward in the adobe soil, the depth being 2 inches for three six-inch irrigations, while this amount of irrigation washed the sodium chloride to a depth of 32 inches, and four three-inch irrigations washed the sodium carbonate to a depth of 20 inches. The sodium chloride moved more freely than the other two salts in both adobe and sandy loam. The above experiments were performed with pure salts. Cameron and Patten (3) found that when using black alkali soils brought from the fields and containing notable quantities of sodium sulphate, besides the sodium car- bonate and small quantities of chlorides, the " neutral salts such as the chlorides in the presence of carbonates can be comparatively readily and completely leached from the soil. With continued leaching of soils contain- ing 'black alkali' there is an increase in the rate at which percolation takes place, due probably to the reduction of the amount of alkali present and its effect on the physical structure of the soil. Soils containing 'black alkali' can be reclaimed by leaching, but the time and the amount of water required are probably much greater than in the case of white alkali." REFERENCES 151 Very little attention has been given to the effect of the different alkalies on the physical conditions of field soils; consequently, it is not known whether or not the rate of movement of salts under field conditions is checked by washing the salts out of the soil as in the above laboratory experiments. The last-mentioned experiment apparently indicates that when the salts are mixed, as under field conditions, the deleterious action of the neutral salts is not so great as under the laboratory mixing conditions. REFERENCES 1. Beeson, J. L. The Physical Effects of Various Salts and Fertilizer Ingredients upon a Soil as Modifying the Factors which Control its Supply of Moisture. Jour. Am. Chem. Soc. 19 (1897), pp. 624- 649. 2. Briggs, L. J., and Lapiiam, M. W. Capillary Studies and Filtration of Clay from Soil Solutions. U. S. D. \. Bur. Soils, Bui. 19 (1902), 40 pp. 3. Cameron, F. K., and Fatten^ H. E. The Removal of Black Alkali by Leaching. Jour. .\m. Chem. Soc. 28 (1906), pp. 1639-1644. 4. DiMO, N. A. Influence of Irrigation and of Increased Natural Hu- midity on the Process of Soil Formation and of the Transportation of Salts in the Soils and Subsoils of the Golodnoi (Hungary) Steppe. Russ. Jour. Exp. Landw. 15 (1914), pp. 136-138. (Abs. E. S. R. 34, p. 16.) 5. DoRSEY, C. W. Accumulation of Alkali in Soil. U. S. D. A. Bur. Soils, Bui. 35 (1906), pp. 13-18. 6. DoRSEY, C. W. Reclamation of Alkali Land in Salt Lake Valley, Utah. U. S. D. A. Bur. Soils, Bui. 43 (1907), 28 pp. 7. Hansen, D. Experiments in the Production of Crops on Alkali Land on the Huntley Reclamation Project, Montana. U. S. D. A. Misc. Bui. 135 (1914), 19 pp. 8. Hare, R. F., et al. Preliminary Tank Experiments on the Movement Changes in Composition and Toxic Effect on Wheat of Certain Salts in Sandy Loam and .A-dobe Soils. N. Mex. Sta. Bui. 88 (1913), 32 pp. 9. Harris, F. S. The Movement of Soluble Salts with the Soil Moisture. Utah Sta. Bui. 139 (1915), pp. 1 19-124. 10. Harris, F. S., and Robinson, J. S. Factors Affecting the Evaporation of Moisture from the Soil. Jour. Agr. Res. 7 (1916), pp. 439-461. 152 MOVEMENT OF SOLUBLE SALTS 11. Harris, F. S., and Butt, N. I. Effect of Irrigation Water and Manure on the Nitrates and Total Soluble Salts of the Soil. Jour. Agr. Res. 8 (1917), pp. 333-359- 12. Headden, W. p. AlkaU in Colorado. Colo. Sta. Bui. 239 (1918), 48 pp. 13. Headden, W. P. Colorado Irrigation Waters and Their Changes. Colo. Sta. Bui. 82 (1903), 77 pp. 14. Headden, W. P. The Ground Water. Colo. Sta. Bui. 72 (1902), 47 PP- 15. Headden, W. P. A Soil Study, III. The Soil. Colo. Sta. Bui. 65 (1901), 53 pp. 16. H1LG.A.RD, E. W., and Loughridge, R. H. Distribution of Salts in Alkali Soils. Cal. Sta. Rpt. 1894-95, pp. 37-69. 17. HissiNK, D. J. The Influence of Various Salt Solutions on the Per- meability of Soils. Jour. Chem. Soc. (London), 92 (1907), No. 542, p. 984. (Abs. E. S. R. 20, p. 16.) 18. King, F. H. Investigations in Soil Management, 168 pp. (Madison, Wisconsin, 1904.) 19. KoLOTOV, G. I. Movement of Salts in Seniiarid Soils. Abs. in Zur. Opyter. Agron. (Russ. Jour. Exp. Landw.), 12 (1911), pp. 832-833. (Abs. E. S. R. 38, p. 421.) 20. KossoviCH, P. S. The Water-raising Capacity of Soils. Russ. Jour. Exp. Landw. 11 (1910), p. 734. (Abs. E. S. R. 38, p. 421.) 21. Kravkov, S. On the Movement of Water and Salt Solutions in Soils. Jour. Landw. 48 (1900), pp. 209-222. (Abs. E. S. R. 12, p. 620.) 22. Loughridge, R. H., and Shinn, C. H. Reclamation Tests with Gypsum in Alkali Soils. Cal. Sta. Rpt. 1891-92, pp. 80-90. 23. McCooL, M. M., and Millar, C. E. Soluble Salt Content of Soils and Some Factors Affecting It. Mich. Sta. Tech. Bui. 43 (1918), PP- S-47- 24. Mackie, W. W. Reclamation of White-ash Lands Affected with Alkali at Fresno, California. U. S. D. A. Bur. Soils, Bui. 42 (1907), pp. 16-17. 25. Muntz, a., and Gandechon, H. The Diffusion of Fertilizer Salts in the Soil. Ann. Inst. Nat. Agron. 2 ser. 7 (1908), pp. 205-238. (Abs. E. S. R. 21, p. 23.) 26. Pagnoul, a. Moisture and Absorptive Power of Soils. Terres Arables du Pas-de-Calais, Arras: 1894, 128 pp. (Abs. E. S. R. 6, p. 118.) 27. Patton, H. E., and Waggaman, W. H. Absorption by Soils. U. S. D. A. Bur. Soils, Bui. 52 (1908), 95 pp. 28. PdcHNER, H. Concerning the Transport of Soluble Salts by the Movement of Water in the Soil. Forsch. Geb. Agr. Phys. 18 (1895), pp. 1-26. (Abs. E. S. R. 7, p. 373.) REFERENCES 153 29. Sharp, L. T. Fundamental Interrelationships l)ct\vecn Certain Soluble Salts ami Soil Colloids. Univ. Cal. Tub. A^r. Sd. i (igi6),|)i). 291- 33^)- 30. TuLAYKOV, N. Some Laboratory Kxpcrimenls on the Capillarity of Soils. Russ. Jour. E.\p. Landw. 8 (1907), pp. 629-O66. (Abs. E. S. R. 20, p. 517-) 31. Tri.AYKov, N., and Kossovich, P. The Soils of the Muganj Steppe and Their Transformation into Alkali Lands by Irrigation. Ann. Inst. Agron. (Moscow), 12 (1906), pp. 27-255. (Abs. K. S. R. 21, p. 818.) 32. Wartngton, R. Physical Properties of Soil, pp. 1S8-231. (Oxford, 1900.) CHAPTER XII METHODS OF RECLAIMING ALKALI LANDS No single method of reclamation is adapted to all alkali lands. Many conditions must be considered in deciding what methods to adopt. The source of the alkali, the texture of the soil, the slope of the land, the depth of the water-table, the price and supply of reclaiming materials, the kind of crops that will grow in the climate, the value of the reclaimed land, and a number of other factors must be taken into account before deciding the advisability of reclaiming a given alkali soil and the methods to be used in case reclamation appears economical. Whatever the method, the goal is the same; each aims to check any in- creased accumulation of salt and to reduce the present harmful quantities of alkali to a point at which the growth of crops will not be hindered. The Source of Contamination. — The first step in the reclamation of alkali land is to discover the source of the salt. Intelligent systems of improvement first discover and remove the cause of the accumulation. As with human disease, an ounce of preventative is worth a pound of cure. Most of the effort spent in securing temporary relief is wasted if the trouble soon returns. Work is done to much better advantage if done with the idea of securing permanent results. As pointed out in Chapter X, alkali comes to the soil in a number of very distinct ways. These must be recog- nized in deciding which method of reclamation is best 154 REDUCING EVAPORATION 155 adapted to the conditions. Where an irrigation canal passes through a formation that is high in soluble salts the water becomes alkahne and carries the soluble material to the land where the water is applied. A canal in a forma- tion of this kind becomes porous when the salts are dis- solved. This allows seepage water to percolate more readily from the canal, increasing the quantity of water which comes out on land below; this in turn causes water- logging together with deposition of alkali salts. Lining the canal with cement over the salt-bearing formation will do more toward permanent reclamation than any number of temporary devices on the land itself which do not remove the source of the trouble. Often a large area becomes water-logged from a single source, and in arid soils water-logging is generally fol- lowed by alkali accumulation. A ditch across the head of the land to cut off the water in cases of this kind will often prevent or overcome the difficulty without applying methods of reclamation on the land itself. Some soils contain a layer several feet below the surface in which the salt is very concentrated. Where this is the case, every effort should be made to prevent a rise of the salt to the surface where it will hinder crop growth. If it remains at considerable depth, it may be entirely harm- less, whereas it might entirely prevent plant growth if it rose to the root zone. These examples show the relation of reclamation methods to the source of alkali. Reducing Evaporation. — The chief method by which alkali accumulates at the surface of the soil is through evaporation. The author (4) has shown the ease with which salts move with moisture through the soil. W^hen- ever water evaporates from the soil surface more water is moved to the surface by capillarity and the process re- 156 RECLAIMING ALKALI LANDS peated. Thus, there may be a constant stream from the subsoil to the surface, particularly if the water-table is Fig. 19. — Typical Hard Pan Found in Arid Soils. within two or three feet of the surface. All the water that moves transports some salt, and since none of the salt can be evaporated, all of it remains as a surface ac- REDUCING EVAPORATION 157 cumulation. If the soil is \cry low in soluble salts no harm may be done, but arid soils usually contain suflicient salt to render high exaporation dangerous. If virgin soil contained 3000 parts per million of alkali, the growth of most crops would not be greatly liindered; but if through a constant movement of salt to the surface the salt of the top four feet were concentrated in the upper six inches, it would contain 24,000 parts per million, which would make it entirely unsuited to crop production with- out reclamation. If evaporation is reduced to a mini- mum, an accumulation of this kind is checked. In the reclamation of alkali land by any method, it is desirable to prevent evaporation as nearly as possible, because evaporation causes the salt to accumulate where it will do most harm. In practice, many devices to reduce evaporation are employed. These usually consist of cultivating the soil, shading it, or the estabhshing of a good mulch by adding manure, straw, leaves, or sand. Of the various materials to be added, manure is usually to be recommended since it has sufficient beneficial effect in addition to the mulch- ing to pay for its use, while others are of questionable economic importance. The most practical means of preventing evaporation is through cultivation. An unstirred soil, particularly if it is heaxy — as many alkali soils are — forms a crust which acts as an excellent conductor of moisture. Break- ing up this crust by cultivation leaves the soil loose and with but few points of connection with the lower layers of soil. As a result evaporation is slight even though the subsoil remains moist. It is particularly important that the land be cultivated soon after irrigation since evapora- tion at that time is especially high. 158 RECLAIMING ALKALI LANDS Harris and Robinson (5) have shown that shade is very effective in reducing evaporation. This suggests the desirabiHty of keeping alkali land constantly shaded, preferably by a crop, which not only shades the soil but also causes the water to pass into the air through the plants without coming to the surface. A growing crop may therefore be considered as one of the most important agencies in the reclamation of land containing small quantities of alkali. A water-table near the surface is the chief cause of harmful evaporation. It is difficult to prevent the pas- sage of large quantities of water to the surface when there is an unlimited supply 2 or 3 feet below. The prevention of alkali accumulation calls for a lowering of the water- table to several feet from the surface. The growing of green manure crops instead of leaving the land uncropped is one way of reducing the surface accumulation of alkali. Plowing Under of Surface Alkali. — Hilgard (9) has shown at the Tulare Substation, California, that the injury caused by alkali was reduced by plowing the surface ac- cumulation under. Part of a very bad alkali spot was trenched to a depth of two feet and the surface soil thrown to the bottom. The spot thus treated produced good wheat crops for two years, which was the time required for the alkali to return to the surface. Ordinary plowing is to some extent similar to the above treatment; hence the tendency of salts to accumulate at the surface by evaporation of water is in part overcome by ordinary field practices. In order that this operation may be effective, the plow- ing should be as deep as possible, since salt turned under only 3 or 4 inches deep would return rapidly to the sur- REMOVING FROM SURFACE 159 face, or even worse, the liighcst concentration would l)e in the soil layer where young plants were getting Uieir start. The plowing under of alkali cannot be considered in any sense as getting rid of it. The most that can be claimed is that injury is retarded till drainage or some other permanent means of elimination begins to operate. Removing from Surface. — In certain cases where most of the salts have accumulated at the surface, it is possible to remove large quantities without the use of covered drains. Surface removal is accomplished by scraping or sweeping off the salt or by dissolving it and then draining off the solution. Scraping and sweeping, in order to be practical, would call for a higher concentration of salt than can be removed by dissolving. Where the salt is to be removed in solution, as may be done in exceptional cases, the land may be diked in such a way that water can be made to stand several inches deep over the surface for a number of hours till most of the salt is dissolved. The solution is then drawn off carrying with it a large percentage of the alkali. Water may in this way be added and drawn off several times in order to make the treatment effective. It is not necessary to let the water stand more than a short time since the salt dis- colves quickly and if allowed to stand would reenter the soil with percolating water. This method is not to be recommended under many conditions. A method of reclamation somewhat similar to the above requires water to stand on the land for long periods. By this means the salt is gradually washed down into the soil out of the reach of plants. Where conditions are favor- able, however, it is much better to carry the salt entirely out of the land by drainage, since it will rise again if simply washed down. 160 RECLAIMING ALKALI LANDS The reclamation of land by flooding is used extensively in the lower Nile Valley in Egypt. Details of the methods used are described by Means (12). After land has been reclaimed by flooding it is desirable to raise a crop that can endure alkah and water till the soil is in a proper condition for other crops. Rolet (12) recommends rice for climates in which it will grow. White sweet clover {Melilotus alba) is also an excellent crop for this purpose. Neutralizing Sodium Carbonate. — The methods used in removing most of the salts are not entirely satisfactory for sodium carbonate, or black alkali. This salt dissolves organic matter from the soil and deflocculates the particles, thereby injuring the soil structure and making the pene- tration of water very slow. The high direct toxicity of this salt also renders it much more harmful than the sulphates. Hilgard and his associates (8), working in CaHfornia, found that under suitable conditions sodium carbonate can be made to react with gypsum to form sodium sulphate and calcium carbonate. The reaction is as follows: NaaCOs + CaS04 = Na2S04 + CaCOg. This changes the alkali from a very injurious to a much less harmful salt. Shinn and Hilgard (15) used 3000 pounds of gypsum to the acre in Tulare, California, with good results. The best results were secured on plats treated with gypsum in connection with drainage. Later reports of the experi- ments made by Hilgard and Loughridge (8) and by Shinn (14) show that the treatment continued to be suc- cessful. In some cases gypsum was used at the rate of 7.7 tons to the acre annually for thirteen years with a gradual amelioration of the alkali spots. In the four OTHER CHKMICAL TREATMENTS 161 years following 1897 a six-acre vineyard received 34,000 pounds of gypsum or about 4^ tons a year. This was applied at a cost of less than four dollars an acre each year which was a small cost in proportion to the returns. As a result of experiments in the San Luis Valley, (Colo- rado, Headden (7) suggests the use of nine pounds of gypsum for each pound of black alkah in the soil and the removal of the alkaU by surface irrigation. Extensive experiments by Breazeale (i) are reported as showing that the field application of gypsum probably has no effect in overcoming black alkali if the soil already contains soluble sulphates in appreciable quantities or if the irrigation water contains these salts. It seems, there- fore that while g}psum is useful under some conditions, it is not by any means a universal panacea for all black- alkali troubles. Other Chemical Treatments. — The use of chemical substances other than gypsum has frequently been tried in overcoming alkali. Symmonds (17) found in pot ex- periments that alkali soil that was treated with 0.2, 0.5, and I per cent of nitric acid produced more than 5 times the yield of wheat that was produced by the un- treated soil. He (16) later carried on a similar experiment in the field where 600 pounds of nitric acid to the acre of land were mixed with artesian well water and sprinkled on the soil. The results showed a great increase in yield due to the treatment. Lipman (10) has obtained excellent results in treating alkali soil with small quantities of sulphuric acid. The use of stable manure on alkali land has long been known to improve it for crop production. It has indirect value in reducing evaporation as well as the more direct action on the soil and plants. 162 RECLAIMING ALKALI LANDS Cropping with Alkali-resistant Crops. — Allowing land to remain uncropped promotes accumulation of alkali at the surface. It is desirable, therefore, to maintain some kind of plant growth on land that is being reclaimed even though the plant is not the most desirable. Any plant growth is better than none. In soils that are so highly- alkaline that no ordinary crops will grow, certain salt weeds will thrive. It is much better to have them grow- ing than for the land to be bare. When these weeds cover the land the temptation is to burn them, but such a practice leaves the alkali absorbed by the plant on the top of the land with the ash. Some alkali-resistant plants take up large quantities of salts, which might be perma- nently removed from the land if the weeds were harvested and hauled off rather than being burned where they grew. In Chapters VI and XIV there is a full discussion of the crops that do well on alkali land. From these lists, crops may be selected for use during the various stages of reclamation. Drainage. — The only permanent way to reclaim alkali land is to remove the excessive salt. This can best be accomplished by some system of drainage, the various t>pes of which are described in Chapter XIII. It may be said, therefore, that alkali reclamation and drainage are almost synonymous terms. Of course drainage is not equally effective under all conditions. Heavy, compact soils containing large quantities of black alkali respond slowly to drainage, whereas open soils which may contain large quantities of sulphates and chlorides may have these salts effectively washed out in a short time. A good example of the rate of removal of salts is had in the Swan Tract (3) near Salt Lake City. Work was begun in 1902 on this forty-acre farm by the U. S. Department DRAINAGE 1 63 of Agricullure Bureau of Soils and the Utah Agricultural Experiment Station cooperating. By the end of igo,^ 5,051,770 cubic feet, or 51.8 per cent, of the water added to the tract came out through the drains. This water carried Table XVII. Alkali Salts Removed by Drainage During Three Years. Swan Tract Near Salt Lake City Month igo2 September October . . November December 1903 January. . February. March .'. . April May June July August . . . September October . . November December 1904 January. . February . March .'. . April May June July August. . . September Total Water Added per .\cre Rain and Snow (.\cre inches) I. 18 11=; 14 13.21 Irrigation (.Acre inches) I .g(l 6.47 5 23 4.66 11.65 14.62 16. 20 2.42 3.88 .28 06 2g 76 64 4.26 09 1323 52 110.72 Total (Acre inches) 1 .96 6.47 I. 18 11=; 1.49 2.06 1.29 1.76 2.63 4-55 11.66 13-35 565 123.69 S.iVLTS .\ddf.d in Irrig.ation Water (Pounds per acre) 696 . 1 2,288.0 1,858 1,655 4,i3'H .■5,192 5,754 85Q 1,378 99 533 732 458 625 938 1,513 3,939 4,692 1,960 Salt in Drainage Water (Pounds per acre) 45,57; 3,805 4,878 8,845 4,695 9,780 5,370 14,768 663 14,178 8,630 13,912 30,544 41,353 2I,C25 3,159 1,099 473 11,891 13,049 9,558 1,537 787 0,634 17,776 14,480 265,889 Net Salts Lost from Soil (Pounds per acre) 2,583 8,845 4,695 9,780 5,370 14,768 663 12,320 6,975 9,774 25,352 35,599 20,166 1,781 1,000 60 11,159 12,591 8,933 599 - 726 5,695 13,084 12,520 223,586 164 RECLAIMING ALKALI LANDS out 3648 tons of salt over the measuring weir in addition to the salt washed to lower depths by percolating water. Tables XVII and XVIII show in detail the rate of re- moval of the salts. Table XVIII. Quantities of Alkali at Different Depths OF Soil on Certain Dates and Composition of Drainage Water. Swan Tract near Salt Lake City September, igo2 May, 1903 October, 1903 October, 1904 Soil Section Alkali in Soil (p.p.m.) Part of 4 ft. Total (per cent) Alkali in Soil (p.p.m. Part of 4 ft. Total (per cent) Alkali in Soil (p.p.m.) Part of 4 ft. Total (per cent) Alkali in Soil (p.p.m.) Part of 4 ft. Total (per cent) First Foot .... Second Foot. . Third Foot... Fourth Foot. . 17,038 19,250 22,075 24,775 20 23 27 30 6,238 8,125 13,325 15,813 14 19 31 63 1,263 2,288 4,125 7,608 8 15 28 49 475 1,600 2,650 6,250 4 13 24 57 Total 83,138 43,501 15,284 3,821 10,975 -• Average — 20,785 10,875 2,744 Chemical Analysis of Drainage Water (in Paris per 1,000,000) Constituent Seepage Water from Tile Drain before Irrigating, Oct. 9, 1902 Drainage Water, June 18, 1903 Drainage Water, April 4, 1904 Drainage Water, May 10, 190S Drainage Water, June 26, 1906 Ca Mg Na K SO4 CI HCO3 CO3 45 96 6,966 319 3,870 7,650 1,329 71 72 257 11,771 260 8,886 12,070 937 55 61 162 7,262 269 3,531 8,881 800 40 37 70 3,660 1-08 2,143 3,958 666 59 37 89 3,924 126 2,288 4,312 695 60 Total Solids . 20,346 34,308 21,006 10,701 11,531 DRAINAGE 165 Hart (6) gives an example of a tract on which before drainage the ground water stood within 2 feet of the surface. A white crust of salts covered the surface and nothing of value grew on the land, the only vegetation being an occasional salt weed. The average salt content for tlie first 4 feet of depth was 2.25 per cent. A drain- age system was installed and in a month so much of the excess water in the soil was removed, that the water- table was practically down to the level of the drains. The drainage water was very high in salt. By the end of the month an analysis showed the salt content of the soil to have been reduced to i per cent. The ground surface was cultivated and irrigated with a limited supply of water and crops were planted. These gave only fair results. Meanwhile the higher temperature of summer had in- creased evaporation and the average salt content for 4 feet was found to have increased to 1.28 per cent in spite of drainage. A near-by uncultivated and unirrigated spot which had been affected to some extent by the drainage system showed an average salt content for the first four feet of 1. 51 per cent. It was evident that drainage alone would never reclaim the tract; hence, a heavy flooding was given which reduced the average salt content for the first 4 feet to 0.43 per cent, less than one-fifth of the origi- nal content. At the same time the near-by uncultivated spot showed an average salt content for the first 4 feet of 1.73 per cent, an increase which was caused by percolation from flooding the adjacent land. Thousands of examples could be given to show the effectiveness of drainage in reclaiming alkali lands. ISIany failures have also been recorded. These have resulted from improper methods which were decided on before all conditions were studied and also from the fact that the drainage system was expected to do everything. 166 RECLAIMING ALKALI LANDS REFERENCES 1. Breazeale, J. F. Formation of "Black Alkali" (Sodium Carbonate) in Calcareous Soils. Jour. Agr. Rsch. lo (191 7), pp. 541-590. 2. Brown, C. F., and Hart, R. A. The Reclamation of Seeped and Alkali Lands, Utah Sta. Bui. iii (1910), pp. 75-92. 3. DoRSEY, C. W. AlkaU Soils of the United States. U. S. D. A. Bur. of Soils, Bui. 35 (1906), 179 pp. 4. Harris, F. S. The Movement of Soluble Salts with Soil Moisture, Utah Sta. Bui. 139 (1915), pp. 119-124. 5. Harris, F. S., and Robinson, J. S. Factors Afifecting the Evapora- tion of Moisture from the Soil. Jour. Agr. Rsch. 7 (1916), pp. 439- 461. 6. Hart, R. A. The Drainage of Irrigated Farms. U. S. D. A. Farmers' Bui. 805 (1917), 31 pp. 7. Headden, W. p. "Black Alkali" in the San Luis Valley. Colo. Sta. Bui. 231 (1917), pp. 3-15. 8. HiLGARD, E. W., and Loughridge, R. H. The Distribution of the Salts in Alkali Soils. Cal. Sta. Rpt. 1895, pp. 37-69. 9. HiLGARD, E. W. Soils, pp. 455-484. (New York, 1906.) ID. LiPMAN, C. B. New Experiments on Alkali Soil Treatment, Univ. Cal. Pub. Agr. Sci. i (1915), pp. 275-290. 11. Means, T. H. Reclamation of Alkali Lands in Egypt. U. S. D. A. Bur. of Soils, Bui. 21 (1903), 48 pp. 12. RoLET, A. Cultivation of Salt Lands. Jour. Agr. Prat. n. scr. 9 (1905), No. 22, pp. 710-712. (Abs. E. S. R. 17, p. 814.) 13. Sandsten, E. p. Reclaiming Niter Soil in the Grand Valley. Colo. Sta. Bui. 235 (1917), 8 pp. 14. Shinn, C. H. Alkali Reclamation at Tulare Substation. Cal. Sta. Rpt. 1899-190X, Pt. n, pp. 204-213. 15. Shinn, C. H., and Hilgard, E. W. Reclamation of Alkali Land with Gypsum at the Tulare Station. Cal. Sta. Rpt. 1893-94, pp. 145- 149. 16. Symmonds, R. S. Experiments with Nitric Acid in Alkaline Soils. Agr. Gaz. N. S. Wales, 21 (1910), No. 3, pp. 257-266. 17. Symmonds, R. S. Note on Action of Nitric Acid in Neutralizing Alkaline Soil. Jour, and Proc. Roy. Soc. N. S. Wales, 41 (1907), pp. 46-48. 18. TiNSLEY, J. D. Drainage and Flooding for the Removal of Alkali. N. Mex. Sta. Bui. 43 (1902), 29 pp. 19. Weir, W. W. A Preliminary Report of the Kearney Vineyard Ex- perimental Drain. Cal. Sta. Bui. 273 (1916), pp. 103-123. CHAPTER XIII PRACTICAL DRAINAGE During the early years of irrigation in America no provision was made to remove the excess water that always collects in the lowlands of irrigated districts. This is one of the chief reasons for the accumulation of alkali. The modern up-to-date irrigation system should include some method of drainage whereby any excess of water is carried out of the land; for there are always a few farmers who, to the detriment of themselves and their neighbors, use too much water. A drainage system laid out at the same time as the irrigation system will in some cases be more simple than one installed after the land becomes a bog. In swampy places drain ditches are constructed with difl&culty and tile cannot be laid evenly and securely. Unfortunately, the reclamation of most alkali land is not undertaken until after the condition has become bad. This means that many difficulties are encountered. Of course it would not be wise to install drainage when the irrigation system is put in unless there is likelihood of water-logging. The problem is doubly complex since not only must the excess soil water be removed but the alkali must also be washed out. Advantages of Drainage. — Where drainage systems are installed on land there is generally a complete transforma- tion; many conditions favoring crop growth are improved. Most important in an alkali soil is the removal of the excessive salt. In many soils where the salt content is 167 168 PRACTICAL DRAINAGE not high enough entirely to prevent crop growth, there is sufficient to reduce the yield to a point that is unprofit- able. The expenses are practically the same in raising half a crop as a full one. In the one case farming is carried on at a loss, and in the other a good profit may be realized. Thus, removing alkali by drainage may make highly pro- ductive miUions of acres of land that is only moderately Fig. 20. — Field Ready for Laying Tile. successful. There are also millions of acres at present wholly unproductive that may be made to yield bounte- ously by removing the alkali. Drainage removes the excessive water from the soil. By lowering the water-table the plant is given a larger root zone from which to draw both food and water. If only the surface foot or two can be drawn on for food the plant cannot be expected to be so well supplied with nourish- ment as it would with a feeding area of five or six feet. ADVANTAGES OF DRAINAGE 169 Strange as it may seem, drainage increases the water supply of tlic i)lant and reduces the injury that is likely to be caused by drought. Roots do not readily penetrate into the ground water. They are confined to the zone above the water-table from wliich they absorb capillary water. Free water is unavailal)le to them. A water-table near the surface means, therefore, that the plant can absorb water from only a hmited area. In case of drought when the water-table is likely to be lowered rapidly the plant has but a shallow root system which is unable to endure drought so well as a root system which extends well into the soil and is able to take up moisture from a deep soil zone. Drainage allows the soil to become warm early in spring. The high specific heat of water makes it slow to become warm. This has great practical significance since a slow, cold soil delays spring work and retards the development of the young plant at a critical period in its life history. Roots require air for their normal functioning. If free circulation of air through the soil is retarded by water- logging, the plant does not get sufficient air for its best growth. This condition reflects itself in the yield. Covered drains promote the free movement of air through the soil; this may help to account for the wonderful results that follow drainage in cases where the water-table is not close to the surface and alkali is not injurious. Going hand in hand with better aeration is the better condition for the growth of desirable microorganisms. Decay of vegetation in absence of sufficient air takes place as putrefaction which results in products toxic to plant growth. Nitrification, nitrogen-fixation, and normal plant decay require air. If it is not present the organisms promoting these beneficial processes will be replaced by undesirable ones. 170 PRACTICAL DRAINAGE Water-logged land has a tendency to heave in freezing. This results in the winter-killing of such crops as alfalfa, clover, and fall grains. Where the soil is not covered with a protective layer of snow, winter-killing may be one of the most serious handicaps to farming. Anything that reduces it will add greatly to the farmer's profits. The tilth, or structure, of the soil is benefited by drain- age. An undrained soil puddles readily, whereas one that is drained tends to form the crumb-like structure which is sought by the farmer. Determining the Need of Drainage. — As with all other expenses, that required for drainage should be investigated before it is incurred. It would of course be folly to spend 15 or 20 dollars an acre draining land that would not be benefited thereby. Drainage is usually carried on to re- move either excess water or excess alkali. In spite of secondary benefits, it is doubtful if it would pay to drain in most cases unless one of these undesirable conditions existed. An excess of water can easily be determined by boring test holes with a soil auger. The surface indications are not an absolutely reliable guide. In many soils having a dry, baked crust at the surface, borings will reveal free water 2 or 3 feet below the surface. The color and thrift of the vegetation are valuable aids in determining the need of drainage, but the final test should be made by the use of an auger. Excessive quantities of alkali can readily be determined by a chemical analysis. Water extracts of the soil can easily be tested for chlorides, sulphates, carbonates, and nitrates. With information of this sort available it is possible to say whether or not some of the salts should be removed. The electrolytic bridge is very useful in this TYPES OF DRAINS 171 connection to determine the approximate concentration of total soluble salts. For exact work, chemical methods should be resorted to, but for general reconnoissance work the bridge can be used to advantage. Types of Drains. — After deciding that the land needs drainage, the next point to settle is the type of system to f«f»w Fig. 21. Boggy Alkali Land that is Difficult to Drain WITH Short Tile. install. No one system is best for all conditions. On some projects a combination of systems can be used to advantage. The open drain on account of its low initial cost has been used rather extensively. It has some advantages and many disadvantages. Among its advantages is the fact that its action is at all times under the observation of the farmer. Any obstruction can easily be found and removed. The fact that the farmer can do most of the 172 PRACTICAL DRAINAGE work himself at odd times and does not have to pay for materials makes it possible at times to put in an open ditch, whereas a closed drain would be beyond his reach. Among the disadvantages of the open drain are the facts that the original cost does not represent the total outlay. Every year, and often several times during the year, open drains must be cleaned. The banks cave off or other obstructions fall in and interfere with the effective- FiG. 22. — Open Ditch Used to Carry Away the Drainage Water FROM A Large Area. Covered Drains Empty into this Ditch. ness of the drain. Weeds growing on the banks and in the bottom of the ditch are a constant source of annoy- ance. Considerable la^nd that could be cultivated if the drain were covered is made useless by the open ditch, which also cuts the land up into smaller fields causing inconvenience in plowing and performing the other farm- ing operations. Open ditches are always a source of danger for farm animals that may fall in them and be injured. These many disadvantages usually turn the preference toward some form of covered drain, except in such cases TYPES OF DRAINS 173 as require a main drain to carry off large quantities of water. Several closed drains. may open into a main open ditch. Many types of closed drains are in operation. The main requirement is to preserve through the subsoil an open channel that will carry off percolating waters. A Fig. 23. — Machine for Making Drains in Heavy Soil without THE Use of Tile. ditch is dug and some material that will maintain the channel open placed in it. Rocks, brush, straw, timber, and tile are all used. In certain heavy gumbo soils a special device known as a gopher machine, shown in Fig. 23, makes a hole through the soil that does not require filling. In this device a tor- pedo about 8 inches in diameter is attached to a subsoiling point, which is held in the ground by a heavy wheeled frame. The depth at which the torpedo is pulled through 174 PRACTICAL DRAINAGE the soil can be regulated by the operator. In making drains this machine begins at the outlet end and moves toward the higher land leaving a gopher-like hole through which the drainage water passes. Such drains can be made 25 feet apart for about $5 an acre. These will last 5 or 6 years in the right kind of soil. If any of them happen to become clogged, new ones may be made between the others. The type of covered drain to use depends on a number of factors.. In wet brush land where rock and lumber are scarce and where tile cannot be had, rush and straw may be used to good advantage, although usually less ef- ficiently than some of the more permanent types. Brown and Hart (3) found lumber drains to be very effective in a swamped soil that would not remain firm enough to hold tile. Rock properly placed in the trench has long been used to keep open the water channel. These various unusual types of drains are unimportant in comparison with tile. The most common kinds are clay tile, either porous or vitrified. Many types of clay tile are to be had. These are so well and favorably known that further discussion seems unnecessary here. Cement tile is being used to some extent, but its use on alkali land is attended with some risk which is explained below. Cement Tile for Alkali Land. — The ease with which cement tile can be made in some localities has encouraged its use for drainage. This has often resulted in failure, because it has been found that under certain conditions the cement is attacked and destroyed by some of the al- kali salts. This observation has led to considerable study on the relation of soluble salts to cements and their de- terioration. Burke and Pinckney (4) found that to cause weakening it was necessary for salt solutions to penetrate the concrete. CEMENT TILE FOR ALKALI LAND 175 Weakening results from the formation of compounds that expand and break up the concrete. Later the soluble compounds leach out leaving the material not nearly so Fig. 24. — Poorly Made Cement that is being Crumbled by Alkali. Strong. Neat cement that excluded absorption was not injured by alkali solutions. Meade (q) found that even very dilute solutions of the salts of magnesium and the sulphates in general have a destructive action on concrete. Cements low in alumina were less affected than others. 176 PRACTICAL DRAINAGE Work done at the U. S. Bureau of Standards (i, 14) shows how Portland cement concrete mortar, if porous, can be disintegrated by the mechanical force exerted by the crystallization of salts in its pore spaces. Mixtures leaner than one part cement to three parts of aggregate were found to be unsuitable for use in localities having a soil high in alkali. Headden (6) found that in the presence of solutions oT sodium sulphate and sodium carbonate a chemical de- composition of the cement takes place with a removal of silicic acid and lime which destroys the cohesiveness of the concrete. Steik (12) found that, of the great number of solutions tested, the 5 per cent sodium sulphate had the greatest disintegrating action. Solutions containing chlorides, sul- phates, and carbonates all had some effect. Mortars were found to disintegrate faster than neat cement, which is similar to the findings of Sims and Dieckman (n). The latter author found that density and age are very important factors in helping cement to resist alkali. Steik believes that the ultimate cause of the disintegration of cement by alkalies is due to the formation of compounds in the cement, which subsequently are removed by solution. These experiments all show the necessity for care in the use of cement tile to drain alkali land, but if the cement is properly made it is fairly satisfactory. Preliminary Survey. — Before actual trenching is be- gun it is important to make a preliminary survey to de- termine the nature of the subsoil and the slope of the land to be drained. A great many test holes made with an auger will reveal the location of pervious and impervious strata. This information is necessary in deciding the depth, location, and direction of the drains. A system LAYING OUT 'VllK SYSTEM 177 installed without taking account of these conditions is likely to be inefficient and expensive. Laying out the System. — After the preliminary survey is made the system can be laid out and the location and depth of each drain determined. The district should be yi Fig. 25. Method of Establishinc. Grade of Drains mapped in such a way that the data obtained in the pre- liminary survey will show the contour of the surface, the texture of the soil and subsoil, and the ground- water condition. On this map the drainage system may be drawn in such a way that intersecting joints, the sizes of tile, and other data can be preserved for future use. These data are extremely valuable in locating trouble. The memory is not sufficiently accurate to be relied on for this 178 PRACTICAL DRAINAGE information, and it is a good idea to preserve the record for the use of some one besides the original drainer of the land. In laying out the system the depth of the drains, the size of tile, the slope of the drain, and the distance apart must be given careful consideration and will vary with each set of conditions. These factors depend somewhat upon each other. For example, the steeper the grade the smaller the tile may be, and the deeper the drain the farther apart they may be placed. In general, tile should be placed from 5 to 7 feet deep and the space between tile lines will usually vary from 200 to 1000 feet. Size of Drains. • — A number of formulas have been worked out to help in deciding the size of tiles that will be efficient and economical. Poncelet's formula for de- termining the velocity of flow in drains, which has found considerable use, is as follows: L + saD in which V = Velocity in feet per second, D = Diameter of tile in feet, F = Total fall of drain in feet, L = Length of drain In feet. Knowing the velocity of flow in a tile of given diameter the discharge may be determined by using the general formula : Q = AV in which Q = Discharge in cubic feet per second, and A = Cross-section area of tile in square feet. SIZE OF DRAINS 179 The number of acres drained is found l)y dividing the discharge by a constant representing the number of cubic feet per second necessary to relieve one acre of a given depth of water in 24 hours. The constants most used are: 0.0052 cu. ft. per second _ 1 ~ 8 in. per acre in 24 h nurs 0.0105 _ 1 ~ 4 24 (C 0.0140 1 — 3 24 ii 0.0210 _ 1 24 a 0.0315 3 24 ii 0.0420 = I 24 (( In using the formula, the number of acres in the water- shed multiphed by the assumed constant may be sub- stituted for Q and the formula solved for the diameter of the tile. Other methods of computing sizes, such as the Chezy-Kutter formula given by Parsons (10), are used. Hart (5) has the following to say about the size of drains for irrigated lands and construction methods: "The spacing of drains in the irrigated section usually is much greater than in humid sections and frequently a single line of drain may effect the reclamation of a con- siderable acreage. From this it will be concluded that larger drains will be required in the drainage of irrigated lands. It has been found that they need not be propor- tionately large, however, since the amount of water which it is necessary to take care of is smaller for a given acreage. In the arid section, there is likely to be a continuous discharge of drainage water throughout the year, and frequently the discharge is very uniform at all times. However, there are certain maximum flows, usually during the period of greatest irrigation application, and it is neces- sary to provide a drainage capacity that will take care of such flows. 180 PRACTICAL DRAINAGE "If only the required capacity of the drain were con- sidered, it would be found feasible to do a great deal of drainage with 4-inch and 5-inch tile, but experience has shown that the use of tile smaller than 5-inch is not satis- factory, while 5-inch should be used only for short branch lines or at the upper ends of branch lines. The following 26. — Types of Lumber Drains Used to Reclaim Boggy Alkali Land. table is offered for purposes of comparing the carrying capacity of tile lines of different sizes, on the assumption that all are laid on the same grade. Table XIX. Relative Carrying Capacities of Tile of Different Sizes One Will carry the discharge of 6-inch tile Two 5-inch tiles One 6-inch and one 5-inch tile Two 6-inch tiles 7-inch tile 8-inch tile One 8-inch tile and one 7-inch tile One lo-inch, one 8-inch, and 5-inch tile; or three 8-inch tiles; or seven 6-inch tiles; or twelve 5-inch tiles SIZE OF DRAINS 181 "As a rule, tile larger than 12 inches in diameter is not used in individual farm drainage. "The size of tile required depends on the amount of water to be carried and on the slope of the drain. The latter can be decided upon when the survey of the land is made and the fall to the outlet is measured. The former is not so easy to determine. It depends on the location of the tract, the nature of the soil, the slope of the ground both on the tract and above it; on the quantity of water used in irrigation and on the method of irrigating, both on the tract and on higher land; on the rainfall and evaporation; on the seepage from reservoirs, canals, and ditches; and on many other factors. Indeed, the de- termination of the required capacity of a drainage system is the most difficult problem confronting drainage engi- neers, and demands their best efforts. Intricate measure- ments and calculations must be made in each instance. It is therefore impossible to give definite instructions in re- gard to this important matter. It is possible, however, to give a general idea of required sizes based on a wide experience under a great variety of conditions. The fol- lowing table is intended to apply to fairly uniform land Table XX. Size of Tile Required to Drain Given Areas HAVING Different Types of Soil Area of Size of Tile Required Gravel (in acres) Clay with Sand Stratum Sand 320 160 80 40 20 10 lo-inch 8-inch 7-inch 6-inch 5-inch 5-inch 1 2-inch lo-inch 8-inch 7-inch 6-inch 12-inch lo-inch 8-inch 8-inch 182 PRACTICAL DRAINAGE not located at the foot of steeper slopes or benches, nor in pockets or depressions, nor in flat river bottoms where it will receive surface run-ofl from higher land, nor where it will receive water from deep sources by pressure. The assumed slope of the tile is 2 feet per thousand feet. "If the soil be compact clay, a given size of tile will drain larger areas than indicated. If the subsoil be joined clay, the 'sand' table should be used. If the drain be located at the foot of a bench or in a gravel pocket, none of the above bases will apply. A better basis for design in such cases is the length of a given size of tile which it is safe to use. A slope of 2 feet per 1000 feet is assumed, as before. The following table will give a rough idea: Table XXI. Sizes OF Tile Required Lengths" FOR Drains of Different Size OF Tile Maximum Length Sand Stratum Gravel 12-inch Fed 5580 3350 1790 1250 800 450 Fed 1250 750 400 280 lo-inch 8-inch 7 inch . . 6-inch . . 180 5-inch "For greater slopes smaller tile is required, and for flatter slopes larger tile is necessary, the variation in capacity being as the square root of the slope. If lumber boxes are used, the openings should be about the square of the tile diameter. "For open ditches the bottom width should be 4 feet and the side slopes should be at least i to i. Thus for a depth of 6 feet the top width would be 16 feet or more, CONSTRUCTIOX METHODS 183 and for a depth of 8 feet the top width would be 20 feet or more. "In the installation of a drainage system it should be borne in mind that the improvement is permanent, and that after the tile is once covered up it is more expensive to uncover and relay it with larger tile than to install a new drain, so it is false economy to cut down on the size of tile. It is much better to err on the side of too great capacity than too small. " Construction Methods. — In man}' instances owing to lack of humus the soils of the arid region are very fluxible when wet and the construction of drainage systems is v^ry difficult and requires painstaking care and ingenuity. Special methods and devices have to be employed, and special machinery has been developed. "Drain hnes must be laid out carefully and grade stakes set. The completed drain must be true to grade and as straight as possible. For hand trenching it is advisable to stretch a cord on the ground along one edge of the proposed trench, to obtain good alignment. To insure accurate grade at all points, grade plants should be set up at each station at a uniform height above the grade of the drain. A stout cord then may be stretched over the middle hne of the trench from plank to plank and every point on this cord will be the given height above grade. Grade may be established at one end of each tile with a grade pole having a length equal to the distance from the cord to the proper location for the tile. This may be accomplished by keeping the cord taut by suspending a tile or other weight at each end and measuring down from the cord at the desired points. "Construction work always should start at the outlet of each line and proceed up the slope, so that the water developed will drain away. 184 PRACTICAL DRAINAGE Fig. 27. — Wood Drains being Used to Drain Boggy Alkali Land. CONSTRUCTION METHODS 185 *'In installing covered drains cither hand labor or trench- ing machinery may be used. Frequently, on small proj- ects, hand trenching is cheaper, but usually on larger projects machines can do the work more rapidly, economi- cally, and satisfactorily. It is preferable to let a contract for the work to an experienced and capable contractor. *'If hand labor is used it usually is necessary to operate with small gangs, ordinarily about a half dozen men to the line, as the trench must be opened from the top to the bottom as rapidly as possible and the tile laid and blinded before caving takes place. The men should work as closely together as practicable and not even the first spading should be taken more than a rod in advance of the tile laying. Each man should remove a spading, moving backward at the same time. The man removing the last spading should also grade the bottom. He should not step on the finished bottom and no one should stand near the edge of the trench, nor should wagons or material of any sort be permitted near the trench. The soil removed from the trench should be placed as far back as it con- veniently may be. The tile should be laid at once and bhnded by means of a few inches of earth caved from the edges of the trench. If the banks tend to cave off in large chunks or slabs it will be necessary to brace them apart with planks separated by stout cross-pieces or trench jacks. "A very troublesome condition is that in which the presence of a wet, pervious stratum near the bottom of the trench causes a lateral and upward movement of the soil in the bottom of the trench. In such a case it is necessary to provide a tight cribbing to shut out the oozing material. It consists of two hea\y timbers held apart by trench jacks, behind which is driven lumber sheeting 186 PRACTICAL DRAINAGE properly matched and beveled at the lower ends to insure a tight fit. The sheeting may be driven by means of a heavy maul and may be removed with a three-legged derrick and a special grabhook. ''If the soil in the bottom of the completed trench is so soft that it will not support a man's weight, wooden racks or cradles should be laid under the tile to keep it in line t,^. *L' -jj^TRi'- Fig. 28.- Drainage Machine with the Digging Wheel above THE Ground. and on grade. If conditions are exceedingly bad it often is advisable to use sewer pipe in place of drain tile, as the bells aid in keeping the line intact. Second quality sewer pipe is suitable and generally may be purchased at about the same price as drain tile. Under ordinary conditions, however, the use of sewer pipe is not recommended, since the cost of freight and hauling is higher than for drain tile and it is heavier and more difhcult to handle. Also, in stable ground it is necessary to dig out places for the bells, which considerably increases the cost of trenching. CONSTRUCTION METHODS 187 "Tile should be laid with extreme care. The joints should be as close as possible, and if the soil is semi-lluid and contains much line sand and silt, it will be necessary to pro\'ide some means of keeping the oozing material from entering the tile joints. Almost all the water enter- ing tile lines makes its way through the joints, practically none entering through the walls of even the more porous Fig. Drainage Machine with ihe J)iggi.\g Wheel in THE Trench. tile, so the covering for the joints must provide for the ready passage of water. Straw makes a very good filter when new, but it is likely to decompose and form a sticky, impervious mass over the joints. Brush and wallows are not satisfactory and render any subsequent removal of the tile very difficult. Graded gravel, ranging in size from sand to pebbles an inch in diameter, makes an ex- cellent filter, but it is not always available. Cinders also are satisfactory. Strips of burlap wrapped about the joints give good ser\'ice. The custom of laying strips of building paper over the joints cannot be commanded, 188 PRACTICAL DRAINAGE since the greatest tendency is for the sand and silt to enter at the bottom and if paper is wrapped tightly entirely around the joints the water itself will be shut out. For genuine quicksand, perhaps the best material is cheese- cloth, which should be doubled once or twice and wrapped carefully about the joint. This material soon decomposes, but in the meantime the soil becomes compacted so that the purpose is served. "The more pervious materials should be placed adjacent to the tile. The backfilling may be done with a plow with three or more horses and a long pole evener, or with a scraper, road grader, or go-devil. Recently power backfillers have been placed on the market. All the soil should be returned to the trench and be banked up over it^ so that future settling will not leave a depression over the drain. "In machine trenching it generally is necessary to draw a portable shield after the machine in which the tile may be laid and bhnded before caving takes place." Outlets and Silt Basins. — The efficiency of a drainage system may be greatly lessened by an ineffective outlet. When the water leaves the drain it should flow away freely and not be allowed to back up in the mouth of the drain, since this condition causes silt to deposit and finally clog the drain. The effectiveness of the drainage system throughout its entire length may be lessened by standing water at the outlet. If the fall of the land does not per- mit of rapid flow from the outlet it may be necessary to let the water run into a pit and then pump it out. This method is in successful operation at Kearney Park, Cali- fornia, in the system described by Weir (13). Here the pumps are turned on by an automatic switch operated by a float. COST OF DRAINAGE 189 Provisions should be made to keep stock from tramping on the outlet and destroying it. In drains that are dry part of the time, screens to keep out rodents and other troublesome animals should be placed over the outlet. Manholes at intervals in the system assist in locating trouble. These manholes may be constructed in such a Fig. 30. — Silt Box with Lid. The Silt that Settles in the Box can be Spaded Out. way that they serve as silt basins and thus eliminate from the system silt that might clog the tile. These silt basins are particularly necessary if the fall of the drain has to be reduced. A good type of combination silt trap and manhole is shown in Fig. 30. Cost of Drainage. — The cost of installing a drainage system varies so much with conditions that definite figures cannot be given. Hart (5) estimates the drainage of irrigated land to vary from $15 to $30 with $20 as an 190 PRACTICAL DRAINAGE average. If the land is so wet as to require cribbing of the trench the cost may run up to $50 an acre or even higher. He says that the price of tile may be figured at about I cent per inch of inside diameter for each foot of length for small sizes and about 2 cents for large sizes. Hand trenching costs from 15 to 25 cents a linear foot for six feet deep. Machine trenching is considerably cheaper but usually costs more than a dollar a rod. The system installed at Kearney Park, CaHfornia, with its pumping system cost $59.59 an acre, but since it was to be used for experimental purposes it was permissible that it be more expensive than a system installed by the farmer for strictly economic purposes. These figures must all be revised to meet post-war prices. REFERENCES 1. Bates, P. H., Phillips, A. J., and Wig, R. J. Action of Salts in Alkali Water and Sea Water on Cements. U. S. Bur. Standards, Tech. Paper, No. 12 (1912), 157 pp. 2. Brown, C. F. Farm Drainage. A Manual of Instruction. Utah Sta. Bui. 123 (1913), pp. 5-55. 3. Brown, C. F., and Hart, R. A. The Reclamation of Seeped and Alkali Lands. Utah Sta. Bui. iii (1910), pp. 75-91. 4. Burke, E., and Pickney, R. M. The Destruction of Hj^draulic Cements by the Action of Alkali Salts. Mont. Sta. Bui. 81 (1910), pp. 41-131. 5. Hart, R. A. The Drainage of Irrigated Farms. U. S. D. A. Farmers' Bui. 805 (191 7), 31 pp. 6. Headden, W. p. Destruction of Concrete by Alkali. Colo. Sta. Bui. 132 (1908), pp. 3-8. 7. Jeffery, J. A. Textbook of Land Drainage, 502 pp. (New York, 1916.) 8. King, F. H. Irrigation and Drainage, 502 pp. (New York, 1899.) 9. Meade, R. K. Experiments on the Action of Various Substances on Cement Mortars. Engin. Rec. 68 (1913), pp. 20-21. 10. Parsons, J. L. Land Drainage, 159 pp. (New York, 1915.) 11. Sims, C. E., and Dieckman, G. P. Investigation of the Effects of Alkali on Concrete Drain Tile near Lake Park, Iowa. Concrete- Cement Age, 6 (1915), pp. 278-281. REFERENCES 191 12. Steik, Karl. The KO'cct of .\lkali upon rorlland ("emt'iit. Wyo. Sta. Hill. 113 (1917), i)p. 71-122. 13. Whir, W. \V. Preliminary Report on Kearniy Xineyard ICxperi- menlal Drain, ("al. .Sta. Bui. 273 (igiO), |)p. 103-123. 14. Wic, R. J., and Williams, G. M. Investigation on the Durability of Cement Drain Tile in Alkali Soils. U. S. Bur. Standards, Tech. Paper, No. 44 (1915), 56 pp. 15. WiLLCOCKS, Wm. Egyptian Irrigation, Chapter \TII, pp. 229-254. (London and New York, 1899.) 16. YoHE, H. S. Organization, Financing, and Administration of Drain- age Districts. U. S. D. A. Farmers' Hul. 815 (191 7), 37 pp. CHAPTER XIV CROPS FOR ALKALI LAND Plants differ greatly in their resistance to alkali. Certain crops, such as the beet, will withstand very large quantities and still produce good yields, whereas others, like blue- grass, resent even comparatively small quantities of any alkali salt. It is therefore of great importance to choose the proper type of plant for the particular conditions. Factors Affecting Resistance. — Certain fundamental problems such as the nature of the alkali-resistant plants, the nature of the soil, climatic conditions, and economic considerations, should be carefully studied before deciding finally on which crop to plant. Perhaps the first thing to consider is the difficulty in getting the plants started in the alkali soil. Some of the best crops for alkali resistance when once started well, of which alfalfa and beets may be taken as examples, must be planted shallow and if the alkali tends to concentrate at the surface during their tender seedling stage, it is very difficult to secure a stand. If, however, the alkali can be kept below the feeding zone of such plants by washing or in other ways while they get a start, satisfactory crops can be secured. As alkah is not so concentrated when the soil is kept well moistened, this condition should be sought while the plants are young. Some varieties of each crop are best suited to resist alkali during the seedling stage; hence it is important to choose seed from successful crops on similar soils where possible. The character of the root system of different plants needs consideration. Shallow-rooted crops, like the cereals 192 FACTORS AFFKCTING RESISTANCE 193 and most cultivated grasses, may fail to give a satisfactory crop because the alkali tends to concentrate near the surface if evaporation is active. This accumulation makes the salts very strong throughout the feeding zone of the plant and, therefore, toxic even when the total quantity of salts in the upper three or four feet is rather small. Deep-rooted plants, like alfalfa and trees, may penetrate the alkali strata by growing in the upper soil while the alkaH is beneath and gradually feeding lower as the alkali accumulates at the surface. In this way some plants not exceptionally tolerant may withstand what seem to be excessive quantities when the whole feeding zone is not considered. Where alfalfa, cotton, and other deep-rooted plants get a good start but encounter a strong alkali stratum at a short distance below, these plants may prove less resistant than the cereals which may feed in the upper less alkaline soil. The latter condition is especially marked when alkah is accompanied by a hardpan or heavy clay subsoil. The same may also be said of soils that are under- lain by a shallow water-table, pasture or meadow grasses and grains making much better crops than the deeper, more resistant crops. Another important factor is the resistance of the plants to reclamation methods. A few crops, among which are alfalfa after once well started, sorgo, rice and berseem clover, can endure the frequent heavy irrigations that may accompany reclamation. The best crop of course depends on the particular conditions, alfalfa doing well with good drainage but not in a soil containing excessive quantities of water, whereas some of the other crops like sorgo may do best where drainage is not so good. During the re- clamation process it is a great aid to have the land shaded or cultivated in order to prevent alkali from rising. Alfalfa 194 CROPS FOR ALKALI LAND and other plants which shade the soil during the great part of the season are preferable to those like grain which leave the land unshaded during spring and again during fall. Beets, fruits, and other crops that are grown in rows and require cultivation are useful because of the mulching, which helps check surface accumulations of alkali. For this purpose it is better to have annual crops which allow the ridges to be leveled down occasionally than perennials which allow alkali to accumulate at the top of the ridges year after year instead of being washed out of the soil. The nature of the soil also has some influence on the choice of crops. With a lifeless clay it is preferable to grow some crop such as rye rather than one Hke beets which requires considerable organic matter and much working of the soil to produce a satisfactory crop. It is frequently profitable to raise rye as a green manure crop to improve the soil conditions before a more exacting crop is grown. A soil without good drainage and where artificial drainage is impractical may often be planted to some of the more resistant forage or meadow grasses which will endure water-logged conditions. Soils with con- siderable organic matter are frequently more moist and the alkali apparently less toxic than in the ordinary alkali soil so that more profitable and less resistant crops may prove best. It is unfortunate that the most tolerant cultivated crops are not well adapted to grow in the climate of most parts of the United States where alkali is found. The date palm, which is perhaps the most tolerant crop for soils containing chloride and sulphate salts, rice, cotton, ber- seem clover, and several other desirable crops are adapted only to the warmer alkali regions. Australian salt-bush, ECONOMIC FACTORS AFFECTING CHOICE 195 which withstands hirgcr (juaiitities of alkali than ahnost any other desirable alkah-resistant plant, does not do well where winters are severe. Economic Factors Affecting Choice. — After knowing the relative tolerance of the various crops and their adapt- ability to the particular conditions, certain economic considerations further modify the choice. With cheap lands in some of the grazing sections, for instance, it might be preferable to plant the land to some permanent grass giving only a medium yield than to use the more resistant crops such as sugar-beets and other high-yielding plants which do best under certain other economic conditions. As a general rule, forage crops are more suited to alkali lands than crops in which quality is more important. Land in the neighborhood of large cities or other places where there is a good market for intensive crops, such as the vegetables and fruits, is often more economically planted to these crops even though they may be somewhat less tolerant of alkali than other crops. The use to be made of the crops also governs the choice for alkali lands. Grain crops will produce a heavy growth of fairly good hay in soil considerably too strong to give satisfactory yields of grain. Likewise, although cotton grown upon certain kinds of alkali lands does not give the line-textured liber so desirable in the manufacture of the high-class cotton goods, it may produce a profitable yield of the coarser grade suitable for other purposes. Sugar-beets will produce excellent yields of roots on land that is high in alkali, but if the quantity of salts, especially sodium chloride, be too large the beets may be so poor in quality that they are lit only for stock feed and not for sugar-making. The quality of sugar cane and of various fruits is impaired when grown upon soils impregnated with 196 CROPS FOR ALKALI LAND certain kinds of alkali, but as long as the yield is sufficiently high to prove economical when used for any purpose con- ditions may warrant the use of such a crop in preference to crops not injured materially by the alkali but which do not fit economically into the cropping system. Where the main object is to reclaim land quickly and put it in condition for the common crops, it is frequently desired to green manure the land, to get good aeration of the soil, to retain a mulch, and to keep all moisture moving downward. For such purposes where the soil contains salts in quantities so large that most ordinary crops fail, sorgo, rye, millet, barley, rape, kale, and a few other high- resistant crops which yield a large quantity of dry matter are used. When the alkali content does not exceed about 5000 parts per million of white alkali, less resistant but more desirable legume crops (sweet clover, alfalfa, Canada field peas, vetch, and horse beans) should be preferred to the above crops, provided the seed-bed can be prepared so that a good stand may be secured. Tolerance of Alkali by Various Crops. — In studying the figures given for the quantities of salts that various crops have been found to endure safely, it should be kept in mind that the character of the plants, feeding system in relation to the alkali, and the nature of the soil as above mentioned will often cause enormous differences with the same plant. Soil, moisture, climate, and perhaps other things will often change the relative tolerance of the dif- ferent crops to some extent so that slight differences in tolerance mean httle or nothing. Unless otherwise men- tioned, the salt as given is understood to be the proportion found in the soil to a depth of four feet. Although this arbitrary unit will be misleading when the concentration of the salts varies at different depths in the soil, as is often FORAGK CROPS 197 the case, it is the most satisfactory method available for comparing the different crops as a whole. Not only is the root system of most ordinary crop plants within the four-foot zone, but also this is the region where a large part of the alkah is concentrated. On most alkaH lands the salts in the first four feet of soil may be drawn toward the surface where they will concentrate. Forage Crops have given more satisfaction for use on rather strong alkaline soils than other cultivated crops as a general rule. Quality in fruit, vegetable, sugar, fiber, and grain crops is frequently so impaired by alkali that the crop is practically worthless for the product ordinarily obtained, but since quantity is the chief requisite for forage the crop serves its purpose when a good yield is obtained. Leguminous plants as a family are very sensitive to alkali, especially sodium carbonate. Hilgard (12) states that alkali even when present in quantities as small as 200 or 300 parts per million is generally harmful to most of the legumes. Alfalfa and sweet clover, especially the latter, however, are among the crops generally recommended as being resistant to alkali. Alfalfa sometimes fails to give satisfactory results on alkali land because it is rather sensitive in the seedling stage. A good stand and healthful growth in its first stages are sometimes secured by driving the alkali below the seed-bed by means of a heavy irrigation. Hilgard places the limit for unaffected growth at about 1650 parts per million total salts, about 300 parts per million of sodium carbonate, or about 1390 parts per million of sodium sulphate. Kearney (17) places the highest successful amount at 4000 parts per million of white alkali, while Means and Gardner {22) state that 4000 parts per million of white alkali caused young alfalfa to become sickly or 198 CROPS FOR ALKALI LAND unhealthy. It is a very sensitive plant to black alkali when in the seedling stage. The limits for an old stand of alfalfa range between 20OO and 7100 parts per million of total salts, according to the various authors. The lower of these limits was for a sandy soil, and Sanchez (25) states that on a loam soil a higher concentration may successfully be withstood. That the crop should produce a heavy mature crop on soil containing 7100 parts per million, most of which was sodium chloride, might have been due to the fact that there was standing water at a depth of four feet and that the salt was considerably diluted by the moisture. Most estimates place the limits between 3000 and 4000 parts per million of w^hite alkali. With black alkali, or sodium carbonate, the observa- tions on old alfalfa land vary between 300 and about 900. These differences are partly due to the differences in the nature of the soil and to the different methods of determin- ing and expressing the results of the analyses. As this salt is generally found in connection with other alkali salts the limit can hardly be expected to be a definite quantity even in soils of like character. Likewise, the quantity of sodium chloride and sodium sulphate endured successfully vary through a wide range modified by the presence of other salts. Where the salt was mostly sodium chloride, the variation assigned by the authorities ranges from 2000 parts per million on a sandy soij to 7100 parts per million on a loam soil well supplied with moisture. It is probable that on a loam soil handled so as to protect it from accumulation of alkali when the crop is not shading the ground and kept well irrigated will support a satis- factory growth of alfalfa when it contains as much as 4000 parts per million of sodium chloride. On a sandy loam SWEET CLOVER 199 in Montana Neill (23) reports a diminished }icld where the alkaU content was about 4000 parts per milhon, mostly of sodium sulphate, while Kearney (17) places the highest quantity under which alfalfa will succeed at 6000 of this salt. Very few important crops will grow with larger quantities of these alkalies in the soil. In most soils, there is a mixture of the salts in various proportions so the limits of the separate salts serve only for general purposes. The high resistance of alfalfa may be assigned to its deep feeding habits in many cases, the feeding roots not being in the alkali zone but being in the purer solu- tions below. Sweet clover {Melilotus alba and M. officinalis) is widely recommended for alkali lands. It is as resistant as alfalfa and is often preferred to alfalfa for alkali land. Coe (i) states that it will withstand so much black alkah that salt grass is the only other crop that can compete with it on this kind of land. It gives more satisfaction than alfalfa on alkali lands which are water-logged or have a shallow water-table. Sweet clover is not ordinarily so satisfactory a forage crop as alfalfa because it is necessary to reseed it every alternate year, whereas alfalfa yields well for years. It is so difficult to secure a good stand of these crops under alkali conditions that it is very de- sirable to have a continuous or perennial crop. Sweet clover is easier to get started on alkali land than alfalfa. It requires more care in harvesting because if it is allowed to grow too long it acquires a disagreeable flavor and it is not so readily eaten as alfalfa. The few observations on the resistance of sweet clover to alkali show it to rank about with alfalfa, so that other conditions being equal alfalfa is the preferable crop. However, on water-logged land or where alfalfa does not thrive for other reasons, 200 CROPS FOR ALKALI LAND and where the crop is desired more as a means of reclaiming the land for other crops in a few years, sweet clover is preferable. It is an excellent green manure to be used in upbuilding alkali land. Other Clovers. — The only other clover that has been found to do well in the presence of large quantities of alkali is berseem, or Egyptian clover. It has been found to endure 4000 to 6000 parts per million of alkali, mostly sodium chloride, under Egyptian conditions, but it has not been used to any extent in this country. It requires mild winters and is sensitive to cold. In Egypt it finds favor in reclaiming alkali land because it withstands flooding and an excessive water content of the soil which accompany reclamation methods. Loughridge (19) found the limit for burr clover to be about 1 130 parts per million of black alkali, which is exceptionally high for this salt. Crimson clover and Birdsfoot clover both withstood 530 parts per milHon, and white clover 630 parts per million of black alkali according to this author. Red clover was not found growing in concentrations greater than 670 parts per milUon of total salts. Vetch ( Vicia saliva and V. villosd) has met with consider- able favor in certain districts because it germinates well on land which will not give a good stand of other resistant crops without considerable trouble. Kearney (17) places the limit for good germination between 4000 and 6000 parts per million of white alkah, and Loughridge (19) found it growing unaffected in a soil containing 4340 parts per mil- lion of total salts, 160 parts per million sodium carbonate, 200 parts per million sodium chloride, and 3980 parts per million of sodium sulphate. It may be used for- pasture or as a green-manuring crop, but since it does not do so well under most alkah conditions and since other crops LEGUMES 201 such as sweet clover mcel the conditions better it has found httle use on alkaU lands. Field peas {Pisum stavium) are said by Kearney (17) to germinate and produce normal seedling growth in the presence of 2000 parts per million of white alkali, mostly sodium sulphate. He states that a good crop of peas can be grown in the presence of 4000 parts per million of this type of alkali, but that this quantity is near the upper limit for the seedlings and consequently a poor stand might be expected. Beans are ordinarily considered to be rather sensitive to alkali, but Kearney (17) classifies broad beans as pro- ducing pods in the presence of 4000 parts per million of white alkali. They are sometimes grown as a green ma- nure on alkali lands but have not found much favor because other crops are better adapted both on account of climatic conditions and because other crops produce more forage. The seed being large, germination is better than with most legumes, but w^here the growing season is not cool the growth is not satisfactory. Neill (23) considers 2000 to 4000 parts per million of alkali, mostly sodium sulphate, as being too much for the seedling stages of beans, but states that 2000 parts per million or less will allow all ordinary Wyoming crops to do well. A number of other leguminous plants, including lupines, lentil, esparcet, and other minor forage plants, have been studied under alkali conditions by Loughridge in Cali- fornia (20), but none have given promise of competing with alfalfa and sweet clover. Grasses. — True grasses are as a family more resistant than the legumes. Some of the wild varieties, such as salt grass and tussock grass mentioned in Chapter VI, rank as the most resistant plants known. The cultivated grasses 202 CROPS FOR ALKALI LAND are generally more sensitive than the wild ones. Observa- tions of the more important meadow and pasture grasses have been made, but the number of different conditions or combinations of salts under which they have been studied makes the limits indicated for them of less value than for plants which have had a larger number of studies made of them. Timothy {Phleum pratens) is reported by Kearney (17) to succeed in the presence of 4000 to 6000 parts per mil- lion of white alkali and perhaps more where the dis- tribution of alkali is uniform. Traphagen (29) places the limit below 10,000 parts per million where the salts are mostly of the sulphate type. Near Baker City, Oregon (3), an average crop was produced on land containing 700 parts per million of sodium carbonate. Timothy, like almost all of the grasses, has very small seed, and it is very im- portant in getting a stand with such seed that the seedbed be free from alkali. Unless the alkali can be washed out of the seedbed until the grasses get a good start, it is al- most useless to seed these crops on alkali land. Timothy can be kept moist throughout the year, and because keep- ing the soil moist dilutes the alkali the growth is much more satisfactory than where less water is used. Orchard grass {Dactylis glomerata) is probably a little more resistant to white alkali than timothy. Kearney (17) places the limit for successful growth between 4000 and 6000 parts per million for the white type of alkali. In California the highest alkali in which it was found growing unaffected was 1260 parts per million total salts, 580 parts per million of sodium carbonate, and 550 parts per million sodium sulphate. Brome grass (Bromus inermis) is one of the most resistant of the tame grasses. It has been found (17) to grow un- GRASSES 203 hindered in the presence of as much as 5000 parts j)er mil- Hon of white alkah and to make a good growth and pro- duce seed with 7000 parts per milHon. In California (20) it was unaffected with 3170 parts per milhon of total salts, 630 parts per milhon of sodium carbonate, 230 parts per milhon of sodium chloride, or 2230 parts per million of sodium sulphate. This is one of the best pasture grasses of the western part of the United States where the land is not kept too wet. Red top {Agroslis alba) has not been tried extensively under alkali conditions but Kearney (17) reports it to succeed in the presence of 4000 to 6000 parts per million of white alkali and to do better than timothy or orchard grass. It grows well on excessively wet lands, lands too wet for even timothy, and in such land can probably withstand as much alkali as any of the important culti- vated grasses. Blucgrass (Poa pratensis). — ^ In CaHfornia bluegrass withstood successfully 670 parts per million of total salts', 380 parts per million sodium carbonate, and 220 parts per milHon of sodium sulphate. It is ordinarily regarded as very sensitive to alkali and this apparently shows it to be one of the most tender tame grasses. In rather extensive tests made by Harris and Pittman (7) it was found to be the most nonresistant crop under investigation. Western wheat grass (Agropyrou) may be regarded as one of the most resistant grasses, as it can be grown success- fully upon soil containing at least 6000 and 8000 parts per million. It is very difficult to get started because of low germination of the seed. The lack of popularity is partly due to this difficulty of getting a start. Japanese wheat grass (Agropyron japonicum) was found by Loughridge in Cahfornia (20) in the presence of 2330 204 CROPS FOR ALKALI LAND parts per niillion of total salts, 840 parts per million of sodium carbonate, 820 parts per million of sodium chloride, or 820 parts per million of sodium sulphate. Rye grass is one of the favorite grasses of Italy and England, but it has not met with much favor in this country except in a few places on the Pacific Coast. Italian rye grass {Lolium italicum) is said by Kearney (17) to succeed in soil carrying 6000 to 8000 parts per milhon of white alkali. Other observations indicate it falls considerably below this quantity, however. Shutt (26) found a good growth with 1387 parts per million of total salts, 900 parts per million of which was sodium sulphate, and Lough- ridge (20) places the limit at 1090 parts per million of total salts, 580 parts per million sodium carbonate, 120 sodium chloride, or 640 parts per million sodium sulphate. The latter author gives 1410 as the limit for good growth on English rye grass {Lolium perenne). Fescue, like rye grass, is an important grass of Europe but has not been able to compete with the other forage crops in this country. Kearney (17) regards it as more resistant to alkali than most cultivated grasses, the limit being between 6000 and 8000 parts per million of white alkali. It is hard to get started and therefore rather unsatisfactory where the more profitable grasses can be grown. Observations by Loughridge (20) indicate the different varieties to resist from 11 90 parts per million to 2180 parts per million of total salts, up to 630 parts per million of sodium carbonate and up to iioo parts per million of sodium sulphate. Meadow fescue {Fescue pratensis) was found by the latter to be adapted to alkali land. Tall meadow oat-grass {Arrhenatherum elatins) is another European grass not grown to any extent in this country, GRASSES 205 but it seems to withstand rather large quantities of alkali. Growth was unhindered in a soil containing 5000 parts per million of white alkali and a good growth was found where 7000 parts per million were present according to Kearney (17). He regards it as about equal to brome grass in alkali resistance, or slightly below western wheat grass. A number of new or minor grasses have been tried on alkali lands in California, but none of them have proved close competitors of the higher-producing standard grasses of the United States, such as timothy and alfalfa. Wild or native grasses are frequently found growing on soil which is very high in alkali. These grasses seldom do well in pastures or meadows and generally do not produce very large quantities of feed. ]\Iany of them are hard to get started on new land; their value is likely to be mainly as range grasses of poor pastures on highly alkaline soil. Salt grass {Distichlis spicata) is probably the most im- portant of the native grasses. It occurs throughout the world under a great variety of conditions. It was observed in the Bear River Valley, Utah (16), growing on soil con- taining from 30,000 to 50,000 parts per million of salts, a large part of which was sodium chloride, and yet it does well in soils containing practically no salt. It shows hardly any preference for the t}'pe of alkali nor the con- centration. It has been found growing apparently unaf- fected on land charged with 8516 parts per million of sodium carbonate (13), a quantity so great that hardly any other kind of vegetation could survive. Of course where the nature of the soil is unfavorable, these large quantities of salts would be too great for the plants to do well, but most alkali land does not contain excessive quantities of salts for this plant. It produces little seed so that It is very difficult to propagate artificially and it is seldom planted. 206 CROPS FOR ALKALI LAND Blue-stem grass {Agropyron occidcntalc) was found grow- ing in a Montana soil (29) containing in the surface foot 320 parts per million of sodium carbonate, 1649 parts per million of sodium chloride, and 24,080 parts per million of sodium sulphate. The average for the upper four feet was 384 parts per million of sodium carbonate and 10,360 parts per million of sodium sulphate. There was a good growth of mLxed grass, mainly blue-stem, in this meadow (29). Tussock grass, or purple top {Sporoholus airoides), men- tioned in Chapter VI as an alkali-indicating plant, with- stands very large quantities of alkali. It is relished by stock but will probably not do well except on the ranges. Alkali meadow-grass {Puccinellia airoides) (24), also mentioned in Chapter VI, may furnish good browsing for stock and if available at the proper time it may furnish profitable hay on moist alkali lands. Prairie grasses were observed by Shutt and Smith (26) in Canada to withstand 700 parts per million of sodium sulphate in the upper 6 inches of soil even where the soil beneath this held over 6000 parts per million and the upper 3 feet averaged 6717 parts per million. Where the upper 6 inches of soil contained 4320 parts per million of sodium sulphate and the average for the upper 3 feet was 9773 parts per million of total salts, there was a poor growth, however. Modiola {Modiola procumbens), a weed introduced into California from Chile, is reported by Loughridge (20) to withstand 13,100 parts per million of total salts, composed of 1 1 90 parts per million sodium carbonate, 10,210 parts per million sodium chloride, and 1700 parts per million of sodium sulphate in the upper foot of soil. It has been found to make an acceptable pasture where alfalfa could GRASSES 207 not be started well. Were it not for the fact that it is a troublesome weed where not wanted, it would probably lind more fa\or as a pasture grass. < Sall-biishcs {Aln'plcx spp.), as noted in Chapter VI, make an acceptable forage where the land is too alkaline to permit successful growth of the better classes of forage plants. There have been a number of attempts to intro- duce these plants as cultivated crops for alkali land. The Australian salt-bush (especially A. semihaccaia) is said to be well adapted to California conditions and to be easily- propagated. Hilgard (13) regarded it as being one of the most promising forage crops for alkali lands, being a quick- growing and high-yielding plant as well as producing hay which is readily eaten by all animals. It is not adapted to climates with severe winters nor to places frequented by summer fogs. It would be of little value outside of a mild climate. Other varieties of salt-bushes have been tried for the more severe interior country and, although where once started, they yield a fairly large quantity of good forage, these plants have received almost no recognition in a practical way. They are so difficult to get started that farmers will not take the trouble to plant them. Giant rye-grass {Elymus condcnsatus) is reported b}- Hilgard (12) as being in about the same class as tuasock grass for alkali resistance (3000 to 31,000 parts per million — tussock). In its wild state it grows in large clumps, but where sown at the rate of about twenty-five pounds per acre it makes a rather uniform growth of coarse but palatable grass or hay for sheep or cattle. When grown on alkali land it generally contains considerable salt which makes it somewhat laxative for horses. Although it is at present not receiving much attention as a cultivated crop, it should occupy more of the soils containing too 208 CROPS FOR ALKALI LAND much alkali for alfalfa, and similar crops. Being a large yielding grass, it is grown as a hay crop on some of the less desirable lands of Oregon and Washington as well as a few other places. Sedges and rusJies frequently form the main growth of alkali swamps or low moist lands. The tuber bulrush (Scirpus paludosus) is recommended by Nelson (24) as being the best of these plants for forage on alkali lands of the moist type. Millets, especially the stout rooted varieties, are among the resistant cultivated grasses. Common, or foxtail millet {Chaltochloa italicd) is classified by Kearney (17) as withstanding 6000 to 8000 parts per million of white alkali, a good crop usually being secured where not more than the lower quantity is present and a fair crop between the two points or even a little above. Barnyard grass {Panicum crus-galli) resists white alkali fairly well ac- cording to Hilgard (13). Proso, or broom-corn millets, {Panicum miliaceum) will produce a good crop in the presence of less than 4000 parts per million of white alkali, but since other crops are usually more profitable with this quantity, and since an excess of alkali is likely to reduce the yield of grain to an unprofitable point, its value on such lands is questionable. Loughridge (20) found Egyp- tian millet {Elusine coracana) growing unaffected in the presence of 1140 parts per milHon of total salts, 580 of sodium carbonate, and 480 of sodium sulphate, and many- flowered millet {Milium multijlormn) in the presence of 1090 total salts, 210 sodium carbonate, 120 sodium chloride, and 440 parts per million of sodium sulphate. Other millets that were tested resisted less than 1000 parts per million. Sorghums are rather resistant, can endure flooding, and are readily cultivated so that they are among the better RAPE 209 crops for reclaiming alkali lands. If the soil can be kept moist by irrigation while the plants are in the seedling stage the crop apparently does not suffer. Kearney (17) places the limit for the saccharine sorghums between Cckx) and 8000 parts per million of white alkali or for an almost assured crop just below these points. He states that these sorghums are among the most resistant plants when in the seedling stage. An Hawaiian (5) experiment showed cane to endure 3357 parts per million of alkali, mostly sodium chloride, the growth being unchecked when the roots of the plants were drawing from free water, but that when the moisture content of the soil fell to 28 per cent there was no growth on a soil containing 1980 parts per million of this salt. The highest quantities of alkali on which Loughridge (19) found sorghum growing unaffected w'as 5100 parts per million of total salts, 620 parts per million of sodium carbonate, 610 parts per milhon of sodium chloride, and 3870 parts per million of sodium sulphate. These limits show that where sorghums are adapted they may be expected to grow on soil too strongly alkaline to permit most ordinary crops to survive. Rape {Brassica napiis and B. olcracca), while practically unknown to the farmers of the United States, is a rather alkali-resistant crop which is extensively used for forage in Europe. The seedling of this crop is very delicate or sensitive to alkali and there is difficulty with the stand where a crust is formed before the plants break through the upper soil. By keeping the soil moist and pa}T[ng close attention to the seedlings little attention will need to be given rape on account of alkali thereafter. The plants withstand, and make a fair growth w^ith, as much as 600c to 8000 parts per million of white alkali and will grow practically unchecked with 4000 parts per million, 210 CROPS FOR ALKALI LAND according to Kearney (17). This crop is not well adapted to the present economic conditions of the United States and it is too troublesome in its seedling stage to gain popu- larity with the American farmer. Grain crops have been tried under a great variety of alkali conditions both as a grain and a forage crop. They may successfully produce forage or green manure on land too strongly impregnated with alkali to yield grain profit- ably. During hot weather, unless the moisture conditions are favorable, grain is likely to become shriveled and hard where the so* contains considerable alkali. Under certain other condi„.ons the alkali may cause the plants to spend most of their energy in leaf production rather than seed. Wheat has been grown for hay on land too strong for alfalfa to either germinate or grow (27). According to Kearney (17), the highest quantity of white alkali per- missible for the successful production of wheat hay was 4000 to 6000 parts per million, while for a grain crop it could successfully endure only 1000 to 4000 parts per million. The author (6), however, found wheat doing moderately well as a grain crop where the top foot of soil contained 8756 parts per million of total salts, 1146 parts per million of sodium carbonate, 1577 parts per milHon of sodium chloride, and 5840 parts per million of sodium sulphate, the average salt content of the top four feet of soil being 11,829 parts per million of total salts, 11 21 parts per million of sodium carbonate, 2334 parts per million of sodium chloride, and 7512 parts per million of sodium sulphate. These quantities are the average of determinations in four different fields in different sections of Utah; enormous quantities of sulphates amounting in some cases to 20,000 parts per million were found in soil growing wheat, but where sodium chloride became a promi- GRAIN CROPS 211 nent salt Ihc (|uantity was much less. Observations b\^ Shutt and Smith (2O) show that on a loam soil with a heavy clay subsoil, wheat made a good growth where the upper six inches of soil contained practically no alkali salts, but the next foot contained 1780 parts per million, and below this over 8000 parts per million of salts most of which was sodium sulphate. When the upper sLx inches contained 1230 parts per million of salts and the ^'''^•^*^:* -^#1^^ Fig. 31. — Alkali Spot in a Grain Field. soil beneath this 7000 parts per million the growth was poor, apparently showing that the upper six inches of soil was the injurious portion. In the Bear River Valley, Utah, Jensen and Strahorn (16) found wheat doing well in a soil the top foot of which contained 5000 to 5600 parts per million of alkali, mostly sodium chloride. Lough- ridge (19) places the limits for unaffected growth at 1520 parts per million total salts for Gluten wheat and 1080 for ordinary wheat. For sodium carbonate Headden (8) states that 400 parts ner miiiion in the soil will prove injurious to wheat, while 212 CROPS FOR ALKALI LAND Jensen and Mackie (15) place the limit of profitable pro- duction below 500 parts per million. The quantity of sodium chloride that may be tolerated without notable injury to wheat has been placed at from 100 to about 5000 parts per million by the various investigators. Few observations have been made where sodium chloride or sodium sulphate were the main salts. Traphagen (29) states that the danger limit for wheat when the salts consist of sulphates, two-thirds sodium sulphate, and the rest magnesium sulphate is about 10,000 parts per million. Considering only the sodium sulphate, this estimate is nearly the same as the figures of Shutt (26) and the au- thor (6), but much above these of Loughridge (19). It is probable that the great discrepancies shown in these ob- servations are partly due to a number of factors such as the nature of the soils, mixtures of the salts, and feeding zone of the roots. The variety of grain, as indicated in the seedling tests noted in Chapter V, would probably have some influence but not so much as the figures indicate. Barley is the high-yielding grain of the West which corresponds to corn in the central states. It is commonly looked upon as being the most tolerant of the ordinary grains for alkali. A number of observations have in- dicated that this crop grows practically unhindered with 2000 to 4000 parts per million of white alkali and that it frecjuently produces a good crop of grain with as much as 6000 parts per million of white alkali in the soil. When grown as a forage crop, there will be a satisfactory yield when the soil contains from 6000 to 8000 parts per million, provided the seedbed is kept fairly free at first, according to Kearney (17). Jensen and Mackie (15) found a poor stand of barley on soil containing 500 parts per million of sodium carbonate, but Holmes (14) states that this GRAIN CROPS 213 quantity will be withstood fairly well. Loughridgc (19) found it to do well in the presence of 740 parts per million of sodium carbonate. Although Dymond and Houston (4) state that barley was growing on soil having been flooded by sea water and containing 16,000 to 20,000 parts per million of salt in the upper six inches of soil, it is probable that the plant roots were not feeding in the zone contain- ing the salts. It withstands black alkali better than wheat. The highest sodium chloride content of soil that barley has been observed to tolerate unaffected was 640 parts per million in a California soil (19) which also contained other salts. Traphagen (29) places 10,000 parts per million of sulphates as the danger limit for barley where two-thirds of this was sodium sulphate. Barley should be more important as an alkali land crop. Oats are generally considered to be intermediate between wheat and barley in alkali resistance. Kearney's obser- vations (17) indicate wheat and oats to be about equal in this respect, but most others show oats to be the more tolerant, especially of sodium carbonate and sodium chloride. The author (6) found 5000 to 10,000 parts per million of total salts in the upper foot and 6000 to Sooo parts per million for the average of the top four feet in soils producing a medium crop of oats. Others indicate much less than this to have caused serious trouble. A very wide difference is noted for the effect of sodium car- bonate, but it appears that from 600 to 700 parts per mil- lion of this salt is as much as is safely withstood. No figures are available for the tolerance of oats to sodium chloride alone or where this salt composes the main alkali, but where much carbonate is present 700 to 1400 is more than the crop can withstand safely. Traphagen (29) places the limit for sulphates the same for oats as for wheat and barley. 214 CROPS FOR ALKALI LAND Rye has been highly recommended as a crop to produce forage and green manure for alkali lands too strong for most ordinary crops. Hansen (5a) used it with good success in reclaiming land containing about 17,100 parts per mil- lion of alkali, mostly sodium sulphate, and was able to re- duce the alkali content of the soil considerably by turning the crop under as green, manure. The seedbed for rye should not contain more than about 5000 parts per million of white alkali, however, or a poor growth will result. With rye, as with other crops to be grown on alkah lands, the quantity of seed sown should be greater than for crops on ordinary land and the seedbed made as free from salts as possible by cultural methods and irrigation. Kearney (17) regards rye as being about equal to barley in alkali resistance, or withstanding for a successful grain crop between 4000 and 6000 parts per million of white alkali. Corn has been found (12, 13, 17) to fail on very weak alkali soils and its production on soils containing large quantities of alkali is not ordinarily to be recommended. Rice has been found to do well in Eg3^pt (17) where the alkali content of the soil was as high as 10,000 parts per million, a large part of which was sodium chloride, but this was under very favorable conditions. The soil can be kept moist or wet in growing rice so that more alkaU may be present without injury than where a lower soil moisture content is maintained. Emmer is usually considered to be about equal to wheat in its resistance to alkali. Grain crops other than the above mentioned have not given promise on alkali lands. Sunflowers were found by Loughridge (19) to endure 3740 parts per million total salt of which 3290 parts per miUion were sodium sulphate. ROOT AND VEGETABLE CROPS 215 Root and vegetable crops often do well on ulkuli lands, although some are rather sensitive and some, such as beets and potatoes, suffer in quality when excessive alkali is present. Sugar-beets have been found to be one of the most satis- factory crops grown on alkali lands in the United States. After they are once well started they will endure enormous quantities of alkaU. Trouble is sometimes experienced in getting a stand where the soil contains more than 2000 to 3000 parts per million of white alkali or about 500 parts per million of black. The quality of the roots is impaired for sugar-making when the alkali consists of sodium chloride or nitrates in appreciable quantities. In alkali soils, such as those of certain sections of Colorado and California in which nitrates form an appreciable quantity of salts, the beets are often over-sized and low in sucrose and purity of the juices. Headden (9) holds that ordinary alkali, essentially sulphates, are not det- rimental, but even comparatively small quantities of nitrates cause injury to the quality of the beets. As sugar-beets, after passing the deUcate seedling stage, feed rather deep in the soil the quantity of alkali that may be present in the surface of the beet land may be very great. Jensen and Strahorn (16) found beets apparently doing well in a soil, the top foot of which contained about 30,000 parts per milHon of alkali, a large part of which was sodium chloride. During the earlier part of the season, these beets were barely able to withstand 15,000 parts per million of alkali in the upper foot even though the moisture content of the soil was rather high. It is fre- quently possible to get a stand of beets by giving the land a heavy irrigation to (lri\'c the alkali below, just before planting. After getting started beets will endure 216 CROPS FOR ALKALI LAND and yield well with 4000 to 6000 parts per million of alkali, provided it consists mostly of the white type. With sodium carbonate or sodium chloride composing a con- siderable portion of the alkali, however, the quantity endured will be less. Beets will endure considerably more sodium carbonate than most of the other important crops of western United States. They have been found doing well on land containing from 500 to over 700 parts per million of this salt. Where the soil is crusted due to the action of sodium carbonate, however, or where it becomes strong about the seedlings, the stand will be imperfect and the yield poor. Sodium chloride has been found to have a deleterious effect on the quality of sugar-beets and where this con- stituent of alkali exceeds 400 to 500 parts per milHon the quality is likely to be inferior, although the growth may be excellent. Beets will endure sodium chloride in the soil in strengths of 2000 to 4000 parts per million, but they will not be fit for sugar-making when grown on such soils. Neither the quality nor the quantity of beets produced in the presence of 4000 to 6000 parts per million of sodium sulphate is likely to suffer after the plants once get a good start. Potatoes have not been found to do well on alkali land. Their quality is usually poor, especially where part of the salts consist of sodium chloride or nitrates. These salts also seem to cause the skin of the potato to be poorly developed so that the keeping quality of the tubers is impaired. Potatoes may be apparently doing well in the presence of as much as 2000 to 4000 parts per million, but they are likely to be watery and of poor keeping quaUty when even as much as 1000 parts per million is present. It is best to plant crops other than potatoes on even the weak alkali land. ROOT AND VEGETABLE CROPS 217 Onions may be regarded as fairly tolerant of alkali, at least in the form of sodium carbonate and nitrates. They were observed (2) making a good growth in a soil containing 4500 to 5700 parts per million of total salts, a large part of which was calcium nitrate. With white alkali, Kearney (17) places the limit as between 4000 and 6000 parts per million. Shutt (26) found them growing well in a sandy loam soil containing 1080 parts per million of total salts of which 530 parts per million was sodium carbonate in the upper six inches, the soil to a depth of 5 feet containing 1800 parts per million total salts of which 1350 parts per million w^as sodium carbonate. The highest quantity observed by Hilgard (13) was 2405 parts per million of total salts. Asparagus is said by Kearney (17) to do well in soil containing as high as 6000 parts per million of white alkali and to be benefited by sodium chloride when in small quantities. Celery will grow practically unaffected where the total salt in the soil does not amount to more than about 4000 parts per million and is said to withstand sodium chloride very well. Radishes were found by Loughridge (19) to be unaffected by 3930 parts per million of total salts, 550 parts per mil- lion of sodium carbonate, or 3240 parts per million of sodium sulphate. Other vegetables have not been found to withstand alkali in large quantities. Sodium chloride seems particularly injurious to vegetables such as radishes, carrots, parsnips, and artichokes, the quality being very poor. The seeds of most of the vegetables are small and the seedlings delicate so that vegetable growing on alkali land is very hazardous. 218 CROPS FOR ALKALI LAND Fiber crops are not of great importance in most alkali sections of the United States at present. There are, therefore, few data for these crops. Flax {Liniuni usitaiissimimi) is reported by Kearney (17) as having produced a good crop where the surface foot of soil contained 4000 parts per million of salts. "The pres- ence of an excessive quantity of salts in the soil below the first foot apparently had no injurious effect." Cotton is being grown in parts of the Southwest where considerable alkali is found. It has been produced ex- tensively under alkaline conditions in Egypt where it was found to be rather resistant to alkali. The quality of the cotton is impaired and the production is considerably reduced where the quantity of alkali is great. For the short-staple varieties where quaUty is not so important the soil may contain 4000 to 6000 parts per million without serious injury, according to Kearney (17). As with the vegetables, cotton is injured in quality more by sodium chloride than the other salts. Like sugar-beets, it is a crop which requires considerable cultivation and it shades the land during its maturity so that the cultural methods tend to keep the alkali from concentrating at the surface. Trees and shrubs have been studied as to alkali resist- ance in the United States very little except in California. It is so difiEicult to determine whether the death of trees and shrubs is due to alkali or to other unfavorable condi- tions that data of practical value are almost unobtainable. A rising water-table is one of the common conditions ac- companying alkali, and as the roots of trees and shrubs are in undrained soil which might kill the trees were no alkali present at all, to what extent the injury can be as- suredly due to alkali is a difficult question. Where the alkali is not evenly distributed the feeding zone of the TREES AND SHRUBS 219 trees is so diflicult to determine that the resistance of trees is a much more uncertain matter to determine than it is for the smaller cultures. Fruit trees and shrubs which might tolerate large quanti- ties of alkali frequently do not gi\e satisfaction because the quality of the fruit is injured by certain kinds of alkaH. This is especially true of the more delicately flavored fruits, such as the peach. In case there is a very ap- preciable quantity of alkali in the soil it is usually better to grow the more resistant forage or grain crops until the land has been reclaimed for fruit. Date palms are the most resistant of fruit trees and per- haps the most resistant of cultivated plants. They are unfortunately not adapted to the alkali lands of the United States with the exception of certain of the southwestern regions. The date palm has been known to grow in the presence of 30,000 to 40,000 parts per million of alkali, largely sodium chloride. Where there are layers of soil containing only 6000 to 10,000 parts per million, this palm will produce abundant crops even where the sur- rounding or surface soil contains enormous quantities of alkali. There is no apparent injury where the soil con- tains no more than 5000 parts per million of the white alkali, although where black alkali is encountered the resistance is less. About 600 parts per million of sodium carbonate, 5000 parts per million of sodium chloride, and 20,000 to 50,000 parts per million sodium sulphate have been successfully withstood. Palm groves are found flourishing where the upper soil contains 15,200 parts per million of alkali and the surface of the ground is white with alkali. The quality of the fruit is apparently not greatly impaired even where the alkali, which is about one-half sodium chloride, reaches a concentration of 10,000 parts per million. 220 CROPS FOR ALKALI LAND Grapes, according to the California observations, are the most resistant fruit which does well in many of the alkali sections. They were found to grow well in soil containing 2860 parts per million of total salts, 630 parts per million of sodium carbonate, 770 parts per million of sodium chloride, or 2550 parts per million of sodium sulphate. Olives were unaffected in a soil containing 2520 parts per million of total salts, 180 parts per million of sodium carbonate, 420 parts per million of sodium chloride, or 1920 parts per million of sodium sulphate. Other fruits tolerated very small quantities of salts, so small that even the mildest alkali land would cause trouble. Orange, almond, fig, pear, and apple trees withstood be- tween 1000 and 2000 parts per million most of which was sodium sulphate, whereas the toxic limit for prune, peach, apricot, lemon, and mulberry trees was below 800 parts per milhon for this type of alkali. Hecke, De Greeff, and Heime (11) found that apricot, peach, and similar fruit trees did not suffer from gummosis when there was salt in the soil about the trees. This would indicate that small quantities of salt in the soil would be advantageous, but the quantity could not be large enough to be called alkali land without causing injury at least to the quality of the fruit. Other trees tested by California experimenters and which withstood over 1000 parts per million of total salts were Kolreuteria 4600 parts per million. Oriental sycamore 2670 parts per million, and eucalyptus trees 2530 parts per million. The former two trees withstood 620 and 200 parts per million of black alkali, respectively, and 790 and 1270 parts per million of sodium chloride, respectively. Eucalyptus trees will withstand very large quantities of REFERENCES 221 white alkali and up to about 400 parts per million of black alkali without apparent injury. Washingtonia palm and camphor trees were rather sensitive to alkali even in small quantities, especially of sodium carbonate and sodium chloride. As these trees are adapted only to the warmer sections with mild winters, they are of little value outside of the Southwest. For the other sections certain of the poplars or cottonwoods are probably the best adapted to alkali lands. Locusts are also likely to do well where the alkah is not too strong. Plants recommended by Kearney (17) as being suitable for hedges and windbreaks are Russian olive {Elaeagnus songorica) (Bernh.) (Gray, F. F. and G.) for moderate alkali, golden willow (probably Salix vitellina aurea) for regions having severe winters, pomegranate {Piinica grana- tum), and tamarisk {Tamarix gallica) which are de- cidedly resistant, for the southwestern alkali lands, as well as certain of the larger salt-bushes. A triplex hreivcri and A. longiformis are the species especially recommended for this purpose. REFERENCES 1. COE, H. S. Sweet Clover: Growing the Crop. U. S. D. A. Farmers' Bui. 797 (1917), p. 13. 2. Connor, S. D. Indiana Soils containing an Excess of Soluble Salts Proc. Ind. Acad. Sci. 1916, pp. 403-404. 3. DoRSEY, C. W. Alkali Soils of the United States. U. S. D. A. Bur. Soils, Bui. 35 (1906), pp. 7-196. 4. Uymond, T. S., and Houston, D. Salt Water Flood of November 29, 1897. Jour. Essex Tech. Lab. Vol. 3, pp. 173-182. (Abs. E. S. R. II, pp. 326-327.) 5. EcKART, C. F. A Consideration of the Action of Saline Irrigation Water. Hawaiian Sugar Planters' Sta. Rpt. 1902. 222 CROPS FOR ALKALI LAND 5a. Hansen, D. Crops on Alkali Land, Huntley Project, Montana. U. S. D. A. Bui. 135 (1Q14), iQ pp. 6. Harris, F. S. Soil Alkali Studies. Utah Sta. Bid. 145 (igi6), pp. 3- 21. 7. H.VRRis, F. S., and Pittman, D. W. Relative Resistance of Various Crops to Alkali. Utah Sta. Bui. 168 (1919), 23 pp. 8. Headden, W. p. Alkalis in Colorado. Colo. Sta. Bui. 239 (1918). 58 pp. 9. Headden, W. P. Deterioration in Quality of Sugar-beets Due to Nitrates Formed in the Soil. Colo. Sta. Bui. 183 (1912), 179 pp. 10. He.\dley, F. B. The Work of the Truckee-Carson Experiment Farm in 1912. U. S. D. A. Bur. PI. Ind. Cir. 122 (1913), pp. 13-23. 11. Hecke, E. van, et al. The Use of Common Salt for the Prevention of Gummosis of Fruit Trees. Jour. Soc. Agr. Brabant et Hainaut, 52 (1907), No. 13, pp. 366-367. (Abs. E. S. R. 18, pp. 948-949.) 12. HiLGARD, E. W. Salts Compatible with Ordinary Crops. Cal. Sta. Bui. 128 (1900), 8 pp. 13. HiLG.ARD, E. W. Soils, pp. 466-481. (New York, 1906.) 14. Holmes, J. G. Walla Walla District, Washington. U. S. D. A. Bur. Soils, Field Oper. (1902), pp. 722-723. 15. Jensen, C. A., and Mackie, W. W. Soil Survey of the Baker City Area, Oregon. U. S. D. A. Bur. Soils, Field Oper. (1903), pp. 1151- II 70. 16. Jensen, C. A., and Strahorn, A. T. Soil Survey of the Bear River Area, Utah. U. S. D. A. Bur. Soils, Field Oper. (1904), pp. 1018- 1019. 17. Kearney, T. H. Choice of Crops for .Alkali Land. U. S. D. A. Farmers' Bui. 446 (191 1), 32 pp. 18. Kearney, T. H. Plant Life on Saline Soils. Jour. Wash. Acad. Sci. vol. 8, No. 5. 19. LouGHRiDGE, R. H. Tolerance of Alkali by Various Cultures. Cal. Sta. Bui. 133 (1901), 42 pp. 20. LouGHRiDGE, R. H. Tolerance of Various Crops lor Alkali. Cal. Sta. Rpts. 1895-96, 1896-97, p. 49. 21. Mead, C. E. Crops for Alkali Soils. N. Mex. Sta. Bui. 33 (1900), PP- 37-39- 22. Means, T. H., and Gardner. F. D. The Alkali of the Soils. U. S. D. A. Bur. Soils, Rpt. 64 (1899) pp. 56-57. 23. Neill, N. p. Soil Survey of the Laramie Area, Wyoming. U. S. D. A. Bur. Soils, Field Oper. (1903), pp. 1092-1093. 24. Nelson, A. Some Native Forage Plants for Alkali Soils. Wyo. Sta. Bui. 42 (1899), 45 pp. 25. Sanchez, A. M. Soil Survey of Provo Area, Utah. U. S. D. A, Bur. Soils, Field Oper. (1903), p. 1141. REFERENCES 223 26. Shutt, F. T., and Smith, K. A. The Alkali Content of Soils as Re- lated to Crop (Irowth. J'rans. Roy. Soc. (Canatla), Sor. Ill (1918), XVII. 27. Smith, J. d. Forage I'laiils for Cultivation on .\lkali Soils. U. S. D. A. Yearbook (i8q8), pp. 535-550. 28. ToTTiNGH.\M, W. K. A Preliminary Study of the Influence of Ciiloridcs on the Cirowth of Certain .Xgricultural Plants. Jour. Am. Soc. Agr. II (iqiq), pp. 1-32. 2g. Traphaokx, F. VV. The Alkali Soils of Montana. Mont. Sta. Bui. 54 (1904), pp. 93-121. CHAPTER XV ALKALI WATER FOR IRRIGATION One source of alkali trouble may be from irrigation water which carries in solution large quantities of soluble salts. Water passing over or seeping through alkah land gradually dissolves the soluble material which it retains in solution. Drainage water coming from land that is high in soluble salts should therefore be thoroughly ex- amined before being used for irrigation. Streams that flow through rock formations, such as the Mancos shale, which contain large quantities of salts are often so strongly impregnated that their waters are rendered injurious for irrigation. Springs or wells are often found containing sufficient soluble salts to make the use of their waters dangerous. A limited quantity of alkali in the water would not be so serious if it were not for the fact that the land on which it is used may already have sufficient alkali so that the addition of any more would make it unfit for crops. Variation in the original salt content of the soil makes it very difficult to determine just how much alkali can be present in irrigation water before it becomes dangerous. Notwithstanding the difficulty of giving exact figures, the problem is so important that it merits the most pro- found study. This is realized when the extensive use of irrigation water is known. About 95,000,000 acres of land, or about 7 per cent of the total area under cultivation in the world, is farmed 224 SOURCES OF CONTAMINATION 225 by irrigation. Tliis area will be greatly enlarged in the future. The 25 or 30 per cent of the earth's surface which receives too little rainfall to allow farming without ir- rigation includes some of the richest known farming land. The southwestern parts of Africa, South America, and Australia; the northern part of Africa; the northern and western parts of North America and Asia; and parts of eastern, southern, and western Europe are all too dry to permit of successful farming without the use of more water than falls naturally on the land. The successful farming of these areas is possible only through irrigation. There is much more land needing irrigation than there is water to supply the need. For this reason, it is important to be able to utilize all available water. Even water that would not be used if sufficient pure water could be had must be utilized. It becomes necessary therefore to know just what are the danger limits of alkali in irrigation water. If the farming of certain lands requires irrigation with water that will render the land unproductive, it is highly desirable to prevent the erection of expensive structures for diverting the water and laborious operations in bring- ing the land into a state of cultivation. Som'ces of Contamination. — Much valuable informa- tion has been gathered in the past on the different phases of the alkali-irrigation-water problem. It has been ob- served that most of the contamination of irrigation streams is due to seepage and drainage waters which find their way back into the rivers and canals. Observations by the U. S. Geological Survey and the U. S. Department of Agriculture show that 65 per cent of the Gila River water (27) and 30 to 40 per cent of the Salt River water (3) (32) found its way back into the rivers after being used for irrigation. 226 ALKALI WATER FOR IRRIGATION Numerous analyses of river and canal waters show the great quantities of soluble salts added to the streams by seepage water. In Colorado, a river increased in total salts from no parts per million to 1178 parts per million in traveling 20 miles (28) ; the Jordan River, Utah, in a course of 14 miles changed from 890 parts per million total salts to 1970 parts per million (11); the Sevier River, Utah (12), in running from Junction to Sigard, a distance of 60 miles, had its total salt content increased from 205 parts per million to 831 parts per million and by the time it had reached Delta, 150 miles from Junction, its salt content had reached 13 16 parts per million; the Pecos River, at Roswell, New Mexico, contained 760 parts per million total salts, and about 30 miles below 2020 parts per million were found and there were corresponding in- creases until at a point about 150 miles below the last- mentioned place, the river contained over 5000 parts per milUon (11) (8). These rivers all illustrate the amount of contamination from seepage water that may occur in almost any river. At places where drainage water from strongly alkali soils empties into streams even greater pollution of the water may be expected. Water passing through a soil containing 20,000 parts per million of alkali in the upper four feet has been found to contain over 34,000 parts per milHon of salts when it reached the drainage outlet (5). Such water emptying into the bed of a small stream, as is frequently done during the height of the irrigation season, may make the further use of this water extremely dangerous. The water of the Arkansas River is very pure at Canon City, Colorado, but it is entirely diverted for irrigation further down. At a point about 120 miles below where seepage had increased the stream to consider- SOURCES OF CONTAMINATION 227 able size again, it held about 2200 ])arts per iiiillion of salts (15). Evaporation from free water surfaces is the direct cause of the high alkali content of certain irrigation waters. Lake Tulare, California, which has no outlet, was once Fig. 32. — The More Tender Trees are being Killed with Rising Alkali, while Alfalfa is Still Unaffected. considered a source of irrigation water. Due to evapora- tion its waters increased in concentration from 1400 parts per million in 1880 to 3500 parts per million in 1888, and to 5200 parts per million in 1889 (20). Irrigation water for the Carlsbad district. New IVIexico, is stored in a large reservoir or lake fed by the Pecos River. It was found that for several weeks in May and June, 1899, the evapora- tion of this water which already contained between 2000 anrl 3000 part? per million of total salts, was equal to over 228 ALKALI WATER FOR IRRIGATION 200 second-feet (11). The Gila River (18) was found to contain 1200 parts per million of total salts on June 5. By June 23 it had risen to 1546 parts per million and by July 8 to 192 1 parts per million. Water from torrential rains not having time to sink into the ground, especially on rather impervious soils, dissolves the surface salts and carries them into the streams below. Where much alkali is concentrated in the upper soil and surface of the catchment basin of the rivers, the high flood waters may become somewhat saline. During 1899 and 1900, studies of the Salt and Gila Rivers of Arizona showed them to contain more salts during flood periods, caused by these sudden showers, than during the low stages when the salt content might ordinarily be expected to be highest (8). Similarly, observations of the Pecos River showed the first flood waters to contain 5100 parts per million of salts, whereas later it contained only 2430 parts per million. The Salinas River, California, affords another example of this type of concentration of salts (48). It therefore cannot be safely stated that high waters are best for irrigation purposes. Streams with their beds running through portions of an alkali stratum of soil may become excessively alkali. Salt Creek, Utah, passes over a part of the bed of old Salt Lake which contains large deposits of common salt. After doing so, its water was found to contain 2300 parts per million of total salts, of which 1629 parts per milhon are common salt. Observed Toxic Limits. — The exact quantity of alkali which renders water unsuitable for irrigation is uncertain; it varies with the soil, the crop, the rainfall, the amount of water used, the drainage conditions, and a number of other factors. OBSERVED TOXIC LIMITS 229 Hilgard (17) (19) states that although 685 parts per mil- lion (40 grains per gallon) of the common alkali salts should be the limit under most conditions, the nature of the salts will modify the hmits considerably. As httle as 342 parts per million of sodium carbonate has in some instances caused serious injury in three or four }ears, while as much as 2739 parts per million of the less toxic salts would not be harmful. From his work in California, Mackie (24) states that where the salts "are principally bicarbonate and chloride of sodium, irrigation v/ater containing more than 600 to 700 parts per million of salt should not be applied except to porous, well-drained soils. Guthrie (13) considers 500 parts per million of sodium carbonate as a tolerable quantity of this salt even when as much as 150 parts per million of sodium chloride are also present. Where the salts are more of the sodium-sulphate type, larger quantities are permissible. Forbes (18) states that with good drainage 1000 parts per million of salts in ir- rigation water is an objectionable but permissible degree of salinity for the soils of the Salt River, Arizona. In the Pecos Valley (26) 2500 parts per million to 3000 parts per million of salts were considered the danger zone where about 50 per cent of the salts in the water were of sodium — mostly sodium chloride and sodium sulphate. Good drainage in the upper part of the valley makes possible the use of water of higher salinity than is possible in lower parts of valleys where the soil is heavier and likel}- to contain more alkali. Land, after being irrigated five years with water containing 3900 parts per milhon of salts, was abandoned because of the accumulation of alkali and seepage water. Experiments in Wyoming (31) show that where only small quantities of water are added, practically all of the 230 ALKALI WATER FOR IRRIGATION salts in the water are retained by the soiL Large quanti- ties of water apphed weekly or semi-weekly kept the salts moving downward continually. Means (25) states that the Arabs in the Desert of Sahara raise good crops of dates, deciduous fruits, and garden vegetables when irrigated with water containing as high as 8000 parts per million of total salts, 50 per cent of which in some cases was sodium chloride. Such alkalinity, however, would not be per- missible except with very resistant crops on light, sandy, or well-drained soils and where great care is given to keep the water from evaporating and concentrating the salts at the surface. Without special attention to drainage, a California soil irrigated with water containing 766 parts per million sodium chloride, 327 parts per million sodium carbonate, and 315 parts per million sulphates was proving injurious to an orchard after three years (19). Impervious clay soils might be injured with water too weak in alkali to have any noticeable elTect on well-drained ones, because of the cumulative effect. Even in a soil with good drainage in Arizona, it was found that when water containing over 1000 parts per million of salts, two-thirds of which was sodium chloride, was applied, 50 to 60 per cent of the salts added in the water were retained by the soil or at least never appeared in the seepage water of the district (8). Soils flooded by sea water for 6 to 8 hours were found to contain 2000 parts per million of sodium chloride in the surface soil where un- fiooded land contained only 100 parts per million. How- ever, in a drainage experiment on the Swan Tract, Utah, an alkali soil containing less than 3000 parts per million of salts in the upper 4 feet of soil, when flooded with water containing about 1500 parts per million of salts yielded TYPICAL ALKALI WATERS 231 drainage water containing over ii,ooo parts per million of salts. The applications of water were large, sometimes as much as i6 inches being applied at one time, which makes a great difference in the retention of the salts by the soil (5). Hawaiian experiments with water containing 2cxx> parts per million of salts show that on a moderately porous soil there was very little accumulation of salt pro- vided occasional heavy irrigation was given (4). Wash- ing the salts out of the soil occasionally with the relatively pure winter and spring waters has proved very beneficial to some alkali districts. In semi-arid sections, the salt content of irrigation water may be much higher than in the arid without causing trouble because the amount of water necessary to supplement the rainfall is smaller and the larger precipitation washes the salts out of the soil much more readily. The U. S. Geo- logical Survey (32) has attempted to classify irrigation waters as good or bad by use of a formula based on the toxicity of the individual alkali salts to field crops. Such formulae, while instructive as to the relative injuriousness of the waters, are subject to criticism because the factors mentioned above modify the limits through a wide range. A formula to be of much practical value must consider these factors. Composition of Typical Alkali Waters. — To show the variation in the salt content of some of the principal streams of the West, the analyses given in Table XXII are pre- sented. It should be kept in mind that these results will not hold strictly for different seasons and different sections of the stream, but they are useful in gaining a general idea of the nature of the alkali in different streams. 232 ALKALI WATER FOR IRRIGATION Table XXII. Analyses of Some Characteristic Alkaline River and Lake Waters of Western United States (July) Salt River, Ariz (Oct.) Gila River, Ariz (Oct.) Colorado River, Ariz... . (June) Colorado River, Ariz. . . (Low water) Pima Ditch, Ariz.. . Buckeye Canal, Ariz 1880, Lake Tulare, Cal 1889, Lake Tulare, Cal 1 89 1, Lake Elsinore, Cal Salinas River at San Lorenzo Creek, Cal Estrella River, Cal San Benito River, Cal Cache la Poudre, 2 mi. above Greeley, Col Platte River below Cache la Poudre, Colo Arkansas at Rocky Ford, Colo. . Mill Creek (cold spring), .Mont. Walker Lake, Nev Pecos River, N. M Arkansas River, Salt Fork, Okla. Cimarron, north of Kingfisher. . Brazo River, Texas Rio Grande River, Texas Jordan River, Utah Utah Lake, Utah Sevier River at Delta, Utah. . . Beaver River, Utah Malad River, Utah Salt Creek, Utah Percentage of Sails CI 594 36.5 17.4 17-5 39-9 17.4 20.3 II. 7 154 13.8 2-S 3-8 4.9 74 23.8 22.6 51-3 53-5 30-9 21.6 35-5 26.9 25.0 23-8 50.0 46.2 HO4 9.2 14.6 35-6 12.5 7-3 16.9 20.8 48.6 30-9 29.0 60.0 60.7 17-3 21.3 43-7 8.6 6.2 25-5 30.1 26.5 30.1 24.1 254 2.9 3-6 CO3 Na I3-I 12.8 28.6 9.6 26.5 19-5 24.9 33-5 35-8 7-9 2-3 38.3 7-3 8.8 2.6 3S-I 17-3 i-S 1.2 •7 7-1 "•5 2.7 8.5 17.9 12. 1 4-7 12.7 40.7 27.2 18^2 I3-I I.I -1-5 ^6 16.7 i.o 17.9 I3-I 54 9.8 12.0 14-5 23-5 34-6 14.0 36-7 38.3 20.8 14.8 26.1 18.3 16.4 25-5 374 28.9 4 ■3 1.4 trace .8 1.8 Ca Mg 6.5 94 12.4 154 6.6 1-5 •3 4-5 6.3 6.6 12.3 13.2 12.8 lO.I I.I 134 1.6 13-7 7.6 5-3 5-3 2.8 3-3 2.9 1.6 SiOi 3-5 5 2. 2 3 (a) 7 5 6 [(b) .6 .8 .6 2.0 3-8 Total Solids P.P.M. 1,391 1,08s 1,045 321 1,210 1,972 1,360 4,910 1,444 3,689 1,131 1,571 1,011 2,134 3,747 2,476 2,384 5,962 11,392 1,136 791 892 1,254 1,316 990 4,395 2,180 (a) 47.9% NaCl. (b) 16.1% Na.COs, 69.0% NaCl, Na2S04, etc., 7.1% CaCOs, MgCOo and silica. No analyses of well waters used for irrigation are pre- sented because well waters have been found to vary so greatly even in short distances that each well must be tested separately. There are certain large artesian basins TYPICAL ALKALI WATERS 233 like that of the upper San Luis Valley, Colorado, the waters of whieh all contain larger or smaller fjuantities of sodium carbonate, — ^ which permit of rough classification. Irrigation w'ell waters seldom change in composition as do open streams because the water is not subject to the various factors causing fluctuations. To show the seasonal fluctuations in the salt content of rivers, analyses of the Salt and Gila Rivers of Arizona (8) are given in Tables XXIII and XXIV. These are excep- tional variations but illustrate how little a single analysis might mean. The Sevier River, Utah, show^s a somewhat less fluctuation because not influenced by flood waters. This is shown in Table XXV (33). Table XXIII. Seasonal Variation in Salt Content of Salt River, Arizona, Expressed as Parts Salt per Million of Water Pate (a) Aug. i-Sept. i, 1899.. (b) Sept. 2-Scpt. 9, 1899. (c) Sept. 10-Oct. 9, 1899. (d) Oct. lo-Oct. 17, 1899. (e) Oct. i8-T)ec. 30, 1899. (f) Feb. 17-May 30, 1900 (g) June i-Aug. 4, 1900. . Total SrtLTS 724 IIOO II42 952 1026 1069 I39I Composition of the Waters Na CI SO4 CO3 Ca Mg K SiOs 122 183 274 309 327 407 279 315 441 409 437 594 979 481 727 748 764 919 802 724 402 437 f)5i 206 III 583 465 529 355 (a) High and low summer water. Average of four weekly composites of samples taken daily. (b) Summer flood water. One weekly composite of daily sample taken. (c) High and low summer waters. Average of four weekly composites of dailv samples. (d) Winter flood water. One composite of daily samples taken. (e) Low winter water. Average of ten weekly composites of daily samples. (f) Low winter water. Average of thirteen weekly composites of daily samples. (g) Very low summer water. Average of eight weekly composites of daily samples. 234 ALKALI WATER FOR IRRIGATION Table XXIV. Seasonal Variation in Salt Content of Gila River, Arizona, Expressed as Parts Salt per Million of Water Date (a) Nov. 28, 1899-Jan. 18, 1900 (b) Feb. i-Mar. 7, 1900 (c) Aug. i-Aug. 14, 1900 (d) Aug. is-Aug. 28, 1900 (e) Sept. i-Sept. 28, 1900 (f) Sept. 29-Nov. 5, 1900. . . . . Total Salts 1 1 36 541 925 471 1085 Composition of the Waters Na CI 401 383 965 .S74 364 SO4 15s 165 947 130 964 145 CO3 653 (393 Ca 524 663 686 836 S7I 937 Mg 264 289 175 IS7 121 178 226 151 SiOa 752 652 266 5" (a) Low winter water. Average of seven weekly composites of samples taken daily. (b) Low winter water. x\verage of five weekly composites of samples taken daily. (c) Summer flood water. Average of two weekly composites of daily samples. (d) Summer low water. Average of two weekly composites of daily samples. (e) Summer flood water. Average of four weekly composites of daily samples. (f) Summer low water. Average of five weekly composites of daily samples. Table XXV. Seasonal Variation in Salt Content of Sevier River, Utah, Expressed as Parts Salt per Million of Water Date Total Salts Composition of the Waters Ca Mg SO^ K CI HCO3 NN July 29 August 12 August 24 September 18.... September 21. . . . October 5 October 19 November 9 958 1104 1268 iigo 1426 1406 1436 1376 74 84 82 92 86 74 84 84 100 87 87 79 83 75 74 74 222 272 288 256 329 328 334 326 10 12 8 10 4 4 II ID 58 90 IIS lOI 221 210 223 204 278 290 284 292 264 249 284 290 1-7 1.6 1 . 1 1-7 •4 .8 ■9 •9 Factors Modifying Toxic Limits of Salt. — Under or- dinary conditions irrigation by the flooding method with TOXIC. LIMITS OF SALTS 235 saline water has been found better than by the furrow method. This is especially the case where such good drainage prevails that large quantities of water may be applied to leach out any accumulation of salts. Experi- ments have shown that land Hooded every 8 days with alkaH water contained less than one-third the quantity of alkali found in the temporary ridges under furrow ir- rigation and about 27 per cent of that found in unculti- vated tree rows. Hawaiian experiments (7) show that with large applica- tions of water containing about 3430 parts per million (200 grains per gallon) of common salt, large quantities of lime, magnesia, and potash are rendered available. Excessive irrigations to prevent the alkali from accumulat- ing at the surface washed out large quantities of lime and magnesia. Soils not well supplied with lime are injured much more by alkali than those well supplied. It was found in Wyoming (31) that alkali irrigation water caused a considerable loss of calcium sulphate and calcium car- bonate from the soil. Experiments in Oregon (i) show that calcium carbonates and nitrates wash out of the soil faster than supplied in the irrigation water. It has been found in some regions that the dissoh'ing action of alkali — the chloride and sulphate salts — on lime destroys the impervious hardpan layer often found a foot or two beneath the surface, thus allowing drainage to go on more freely. In the Southwest, especially in New Mexico, certain of the streams carry calcium sulphate in solution some of the time. The salt neutralizes and makes less toxic the sodium carbonate found at times in the soils of the district. If but little or no black alkali is present, as is the case in that of the Pecos River irrigation water may contain 236 ALKALI WATER FOR IRRIGATION much larger quantities of total salts than would other- wise be permissible. On soils where an impenetrable hardpan exists, sometimes caused by sodium carbonate, the permissible salinity is generally lower than without such a condition. During dry years, a single irrigation with alkali water may mean the difference between a crop and a failure, provided the crop can withstand the alkali in the water. The limits in such cases might be much higher than in cases where it is necessary to irrigate frequently. On a clay loam soil containing a medium quantity of alkali in the Bear River Valley, Utah, the use of irrigation water containing 4395 parts per million of total salts, 3625 parts per million of which was sodium chloride, caused almost immediate wilting or death of grain. In the Carlsbad district, New Mexico (26), water containing 4352 parts per million total salts consisting of 1682 parts per mil- lion sodium chloride and 600 parts per million sodium sulphate injured young sugar-beets when freely applied. In Europe (37) the use of irrigation water containing 5CC0 to 10,000 parts per million of salt caused dwarfing of the better grasses and legumes so that the yield was considerably reduced. Seedling grass was killed with these concentrations and even 500 to 1000 parts per mil- lion injured the stand. Corn (2) suffered during its vegetative period when irrigated with chloride and carbonate waters in concen- trations as high as 7389 parts per million, but tomatoes did not. Sugar cane (6) (7), when irrigated with pure water, yielded 11 tons more sugar per acre than when ir- rigated with water containing 3430 parts per million of salts. The density of the cane juice was lowered and the salt content raised by the use of the alkali water so that REFERENCES 237 the purity of the juices and the quantity present was re- duced. In these experiments 6.75 and 8.79 acre-feet of water were applied during the season and occasional hea\'y irrigations were given to keep the salts from accumulating. \\ hen the quantity of water used was reduced considerably so that the strength of the soil solution became high such a large quantity of alkali proved fatal (6) (7). Using cofifee, cocoa, and other plants to determine the concentration of water that may be used with safety (22), it was found that the limits were between 5000 and 15,000 parts per million although the result were somewhat complicated by rainfall. From a survey of a number of localities along the Potomac River, Scofield (30) assumes that the salt water limit for wild rice is about 1754 parts per million (0.03 normal) for sodium chloride. The growth was just about proportionate to the strength of the solution when less than this amount was present. Water to be used in irrigating rice should never contain more than 3000 parts per million of salt, according to Fraps (9) of Texas. Harris and Butt (14), after a rather extensive study of the use of alkali water for irrigation, concluded that under average conditions more than 500 parts per milhon of sodium carbonate, 1000 parts per million of sodium chlo- ride, 4000 parts per million of sodium sulphate, and 4000 parts per million of the ordinary mixture of salts are dangerous. In case there were no drainage from the land, lower limits than those mentioned would have to be used. REFERENCES I. AiLEN, R. W. Work of the Umatilla Reclamation Project Experi- ment Farm in 1Q15 and 1916. U. S. D. A. Bur. PI. Ind., W. 1. A. Circ. 17, p. 17. 238 ALKALI WATER . FOR IRRIGATION 2. BoRDiGA, O. Irrigation Experiments with Brackish Water. Intm. Inst. Agr. (Rome), Mo. Kul. Agr. Intel, and Plant Dis. 4 (1913), No. 8. (Abs. E. S. R. 30, p. 886.) 3. Code, W. W. Irrigation in the Salt River X'allcy (Arizona). U. S. D. A., O. E. S. Bui. 104 (1902), p. 555. 4. Crawley, J. T. Water-holding Power and Irrigation of Hawaiian Soils. The Application of Nitrate of Soda; the Accumulation of Salt in Hawaiian Soils. Hawaiian Planters' Mo. 21 (1902), No. 8, pp. 358- ,363- (Abs. E. S. R. 14, p. 555.) 5. DoRSEY, D. W. AlkaU Soils of the United States. U. S. D. A. Bur. of Soils, Bui. 35 (1906), 196 pp. 6. EcKART, C. F. Recent Experiments with Saline Irrigation. Hawaiian Sugar Planters' Sta. Bui. n, p. 14. (Abs. E. S. R. 16, p. 650.) 7. EcKART, C. F. A Consideration of the Action of Saline Irrigation Water. Hawaiian Sugar Planters' Sta. Rpt. (1902), pp. 24-74, 76-100; Rpt. (1903), pp. 37-41. 8. Forbes, R. H. The River Irrigating Waters of Arizona — Their Character and Effects. Ariz. Sta. Bui. 44 (1902), pp. 145-214. 9. Fraps, G. S., The Effect of Salt Water on Rice. Tex. Sta. Bui. 122 (1909), 6 pp. 10. FuLAYKOV, N., and Kossovich, P. The Soils of the Muganj Steppe and Their Transformation into Alkali Lands by Irrigation. Ann. Inst. Agron. (Moscow), 12 (1906), pp. 27-255. (Abs. E. S. R. 18, p. 818.) 11. Gardner, F. D. A Soil Survey in Salt Lake Valley, Utah. U. S. D. A. Bur. of Soils, Rpt. 64, pp. 77-114. 12. Greaves, J. E., and Hirst, C. T. Composition of the Irrigation Waters of Utah. Utah. Sta. Bui. 163 (1918), 43 pp. 13. Guthrie, F. B. Water on the Farm. New South Wales, Dept. Agr. Farmers' Bui. 121, 42 pp. (1918). 14. Harris, F. S., and Butt, N. I. The Use of Alkali Water for Irriga- tion. Utah Sta. Bui. 169 (1919). 15. Headden, W. P. A Soil Study, IV. The Ground Water. Colo. Sta. Bui. 72 (1902), 47 pp. 16. Headden, W. P. The Waters of the Rio Grande. Colo. Sta. Bui. 230 (1917), pp. 3-62. 17. HiLGARD, E. W. The Quality of Irrigation Water in the Great Valley, California. Cal. Sta. Rpt. 1890, pp. 4-56. 18. HiLGARD, E. W. Quality of Irrigation Water, pp. 246-251. (Soils, New York, 1906.) 19. HiLGARD, E. W. The Use of Saline and Alkali Waters in Irrigation. Cal. Sta. Rpt. 1897-98, pp. 99-117. 20. HiLGARD, E. W. The Lakes of the San Joaquin Valley. Cal. Sta. Bui. 82 (1889), 4 pp. REFERENCES 239 21. Jenson, C. a., and Strahorn, A. T. Soil Survey of the Bear River Area, Utah. U. S. D. A. Bur. of Soils, Field ()[)er. (1904), pp. 995- 1020. 22. Ki ijri;i<, J. KlTectsuf Usiii^; Salt Sokilioiis for Walcriiit; and S|)riii- kling Plants. Dept. Landb. SuriiianiL- iiul. 2.S (1912), i)p. 25-31. (Abs. !•:. S. R. 29, p. 218.) 23. LipriNCOTT, J. B. Storaf^e of Water on Gila River, Arizona. U. S. (leol. Survey, Water Supply Paper S3> P- 24. 24. Mackie, W. W. Reclamation of White Ash Lands .\fTected with Alkali at Fresno, California. U. S. D. A. Bur. of Soils, Bui. 42 (1907), P- 32. 25. ^Ie.\ns, T. H. The Use of Alkaline and Saline Waters for Irrigation. U. S. D. A. Bur. of Soils, Cir. 10 (1903), 4 pp. 26. Means, T. H., and Gardner, F. D. A Soil Survey of the Pecos Valley, New Mexico. U. S. D. A. Bur. of Soils, Rpt. 64, pp. 36-76. 27. Newell, F. H. Stream Measurements for 1898. U. S. (ieol. Survey, .\nn. Rpt. 1899-1900, Pt. IV, pp. 343-347. 28. O'Brine, D. Alkali vSoils of Colorado. Colo. Sta. Bui. 9 (1889), pp. 22-23. 29. Otto, R. The I'lffect of Salt Water on Plants. Ztschr. Pflanzenkrank, 14 (1904), No. 3, pp. i36-'i4o. (.Vbs. E. S. R. 16, 951.) 30. Scofield, C. S. The Salt Water Limits of Wild Rice. U. S. I). .\. Bur. PI. Ind. Bui. 72 (1905), pp. 9-14. 31. Slosson, E. E. Water Analyses. Wyo. Sta. Bui. 24 (1895), pp. 99- 141. 32. Stabler, H. Irrigation Waters. U. S. Geo. Survey, Water Supply Paper 274, pp. 177-181. ^;i. Stewart, Robert, and Hirst, C. T. The Alkali Content of Irriga- tion W'ater. Utah Sta. Bui. 147 (1916), p. 13. 34. Van Winkle, W., and Eaton, F. M. Quality of the Surface Waters of California. U. S. Geol. Survey, Water Supply Paper 237. 35. Widtsoe, J. A. Irrigation Practice, pp. 77, 84. (New York, 1914.) 36. WiLLCOCKS, W. The Nile in 1904, p. 63. (London and New York, 1904.) 37. Wohltman, F. The Effect of Salt Water on Cultivated Plants. Fuhling's Landw. Ztg. 45 (1896), No. 15, pp. 155-159. (.\bs. E. S. R. 7, p. 680.) CHAPTER XVI JUDGING ALKALI LAND A KNOWLEDGE of the physical phases of alkali is not sufficient; the economic questions in connection with it must also be given consideration. Alkali has no special practical interest except in its relation to the soil, which it may render entirely worthless if present in certain forms and in sufficient concentration. In its less injurious forms and at low concentrations it may reduce the value of the land but slightly. It is important, therefore, to be able to judge the extent of reduction in value of land due to the presence of alkali. Many tracts have been settled, and, after the expenditure of large sums of money, abandoned. This loss might have been saved had a proper examina- tion of the soil been made. Geology of Region. — In regions free from alkali no particular attention need be given to it in judging land, but in regions where alkali is known to exist, it must be kept constantly in mind by prospective purchasers of land. Since practically all of the arid parts of the world have more or less alkah, the ability to judge alkali land is very important. One of the first steps is to look into the origin of the soil to see if it came from geological formations that are high in soluble salts. Soils derived from sand- stones and shales of certain formations are practically always so highly charged with salts that crop production is difficult until the salts are leached out. A soil coming from a formation of this kind, even though it has a salt 240 GEOLOGY OF REGION 241 content similar to that of a soil from a limestone forma- tion, should be regarded with greater suspicion than the latter soil because of the possible recontamination from i^ Fig. ^s- — ''^ Layer of Alkali Sevi i ' i ; i s : i ^w im: Surface. The Possibility of such a Layer Makes an Analysis of the Soil Necessary before it can be Properly Judged. the unlimited supply of salt in the country rock. A knowl- edge of the geology of a region, therefore, is a valuable supplement to other information in judging alkali land. 242 JUDGING ALKALI LAND General Appearance. — One who is familiar with alkali can tell a great deal by the general appearances of the land. The presence of surface accumulations of salts, the nature of the crust, the general condition and kind of vegetation, the appearance of the subsoil in cuts and excavations, the slope of the surface, the soil texture and structure, and numerous other general appearances are helpful in judging alkali conditions. These superficial observations, however, must not be relied on completely. For example, a soil having a high gypsum content and being free from the highly soluble salts may, through constant evaporation of water at the surface, cause the soil to be covered com- pletely with white powdery crystals which would seem to indicate a serious alkali condition. Land of this character could easily be undervalued since the gypsum is not suf- ficiently soluble to cause injury to vegetation and its presence might not be undesirable. On the other hand, a soil may show very little surface indication of alkali; it may contain a good growth of certain kinds of vegetation; yet an analysis might show that at some distance below the surface there is a layer of soil that is highly charged with salts. This land would only need to be brought under cultivation and irrigated to make the subsoil alkali a real source of danger. Appearances are helpful, but alone they are not sufficient. Native Vegetation. — As already discussed in con- siderable detail in Chapter VI, the native vegetation is one of the most valuable indicators of the presence of dangerous quantities of alkali. It is probably the best single means of judging alkali land. Certain plants such as sagebrush {Artemesia tridcntata) do not live in the presence of high concentrations of salts and where these plants are found growing vigorously the land may ANALYSIS OF THE SOIL 243 he considered to be conii)arati\'ely free from alkali. Certain other i)lants such as salt f^rass (Distichlis spicala) are sel- dom found except on land hi<^d-ily charged with sail, and where found the soil should be thoroughl}- investigated before an attempt is made to use it for agriculture. Since this question has already been so fully discussed, no de- tails will be given here. Chapter VI should be consulted for further information. The Water-table. — Alkali lands are often wet. Sur- face accumulations of salt usually result from a rapid evaporation of water which rises from a water-table that is comparatively near the surface. There are soils high in alkali with a water-table hundreds of feet below the surface. In these soils the ground w^ater has nothing to do with the alkali accumulation. Soils are frequently found containing a medium quantity of salt distributed through considerable depth. With the introduction of irrigation and a consequent raising of the water-table to within a few feet of the surface, an ideal condition is pro- \'ided for a concentration of these diffused salts at the surface. This may render entirely unproductive a soil that previously raised good crops. A thorough knowledge of ground-water conditions is, therefore, important be- fore a person is able to make an intelligent judgment re- garding alkali land. Analysis of the Soil. — It is impossible to get an adequate idea of alkali land without having a chemical analysis of its water-soluble material. As has already been explained, a superficial examination may be somewhat deceiving, and it is necessary to know the nature and concentration of the salts to considerable depth before being able to tell definitely how the soil will act and whether or not the alkali is likely to cause trouble. The depth to which the soil 244 JUDGING ALKALI LAND should be analyzed depends on a number of factors. Four and 6 feet are often taken as standards but lo feet is better. At least an occasional sample should be taken to this depth to see that in the deep subsoil there is not a layer of high concentration that will cause trouble later. The exact determinations to be made will depend on the thoroughness of the investigation desired. A complete chemical analysis of all the water-soluble material would be desirable, but a fair idea can be had with much less work. An absolutely necessary determination to any sort of intelligent diagnosis would include total soluble salts, chlorides, carbonates, and sulphates. In comparatively few regions where nitrates are high, they should also be determined. Where any large part of the sulphates are calcium sulphate, calcium should be determined in order that the calcium sulphate may be subtracted from the total soluble salts and the sulphates. Calcium sulphate is not sufficiently soluble in the soil solution to be toxic to vege- tation, but where comparatively large quantities of water are used in extracting the soil for analysis, considerable calcium sulphate is contained in the solution, and where it forms any large part of the dissolved material it should be taken into consideration. It is also desirable to have determinations made of other bases such as magnesium and sodium, but these determinations are not so valuable as the others that have been mentioned. The methods of analysis, particularly the method of making extractions, must be taken into consideration in interpreting the results. Different methods give different results; consequently the methods should always be known. Details of the various methods are given in Chapter VII. Possibility of Reclamation. — The value of alkali land is affected very materially by the possibility and the ex- ECONOMIC FACTORS 245 pcnsc of reclaiming it. Some alkali lands are so situated that reclamation is practically impossible or would be so expensive as to be prohibitive. Very flat land that does not have an outlet for drainage is difficult to reclaim. Land that is so heavy that drainage water percolates slowly has its salts washed out with difficulty. Some lands have a good slope and the soil has a texture suitable for drainage, but there is no available supply of water to aid in the process of reclamation; hence, drainage is useless. It is apparent, therefore, that not only the quality of the soil itself must be taken into account, but also the condi- tions associated with its reclamation. Economic Factors. — Physical features of the soil must be used in connection with a number of economic factors in judging an alkali soil. The soil has no particular value aside from the economic returns it will yield. These depend not alone on actual crop yields, but also on cost of production, market conditions, and a number of other factors. Distance from market and from suitable farm help may make it unprofitable to cultivate even a fertile soil, much less a soil the productivity of which is decreased by any unfavorable condition such as the presence of alkali. Climatic conditions may not be such as to make possible the raising of profitable crops that are resistant to alkali. A soil of a given alkali content might be suitable for agri- culture in a region where date palms could be produced at a profit and yet be entirely worthless for the crops of the temperate zone. It is evident, therefore, that alkali soil of any particular type or composition cannot be said to be suitable for agriculture without taking into con- sideration numerous conditions other than those associated with its merely physical features. The demand for an increased acreage of land to supply 246 JUDGING ALKALI LAND food for the world will make it necessary to use more and more the lands that were previously not considered worthy of cultivation. This will demand that greater attention be given to alkali lands, and that more intelligence be put into understanding and reclaiming them. INDEX Absorption of: salts by soils, 109 water, 34 Abyssinian highland, source of soil, II Acid, sulphuric, beneficial, 116 Action, mass, 106 Advantages of drainage, 167 Afghanistan, alkali in, 13 Africa, alkali in, 10 Alberta, alkali in, 7, 8 Aldajem, R., 28, 32 Alexandria, rainfall of, 11 Alfalfa, 197 Algeria, alkali in, 10 Ali, B., 103, 134, 139 Alkali: black, formation of, 108 -heath, as alkali indicator, 63, 69 -indicating plants, descri|jtion of, 74 -loving plants, 63 meadow-grass, 206 meadow-grass, as alkali indi- cator, 64 movement, rate of, 148 -resistant crops in reclamation, 162 salts, antagonism between, 113 waters, composition of, 231, 232 water for irrigation, 224 Almond, 220 America, alkali in, 6 American cowslip, as alkali indicator, 64 Ames, J. \V., 14 Ammonification, efTect of salts, 138 Analysis : by biological method, 103 by freezing-point method, 102 of Egj-ptian soil, 12 of soil in judging land, 243 Analytical methods, comparison of, 8S Analytical process, 90 Antagonism, 105 between alkali salts, 113, 138 noted in soil bacteria work, 116 Ancient seas as source of salts, 22 Appearance in judging land, 242 Apple, 220 Apricot, 220 Arabia, alkali in, 13 Area affected with alkali, 4 Argentina, alkali in, 10 Aridity necessary for alkali, 6 Arizona, alkali in, 8 Arizona method of alkali analysis, 84, Si- Arrow: grass, as alkali indicator, 64 weed, as alkali indicator, 63, 73 Asia, alkali in, 13 Asparagus, 217 Aster, as alkali indicator, 64 Atroplex, as alkali indicator, O3, 70 Atti, R., 14 Australia, alkali in, 14 Australian salt-bush, 207 247 248 INDEX B Bacterial activities increased by drainage, 169 Baluchistan, alkali in, 13 Bancroft, R. L., 14, 57, 58 Barley, 212 Barnes, J. H., 103, 134, 139 Barnyard grass, 208 Bases, determination of, 92 Bates, P. H., 190, 191 Beam, W., 102, 103 Becker, A., 120, 131 Beeson, J. L., 149, 151 Bemmeln, J. M. von, 121, 130 Bicarbonates, determination of, 86 Biological: activity, toxic limits for, 135 conditions and alkali, 132 inactivity and soil sterility, 133 method of analysis, 103 Birdsfoot clover, 200 Black alkali: formation of, 108 neutralizing, 160 Bluegrass, 203 Blue-stem grass, 206 Bombay Presidency, alkali in, 13 Borates, effect on capillarity, 128 Bordign, O., 238 Bouyoucos, G. J., 102, 103 Breazeale, J. F., 29, 32, 40, 50. 54, 58, 59, 117, 130, 160, 166 Brazil, alkali in, 10 Bridge method, 94 Briggs, L. J., 80, 128, 129, 130, 131, 144, 151 British Columbia, alkali in, 7 Brome grass, 202 Brown, C. F., i66, 174, 190 Brown, P. E., 15, 103, 136, 138, I39 Bryan, H., 104 Bud-brush, as alkali indicator, 64 Buffum, B. C, 45, 51, 54, 58 Bulrush, 208 as alkali indicator, 64 Burd, J. S., 14 Bureau of Soils publications, 9 Bureau of Standards work on ce- ment, 176 Burgess, P. S., 118, 139 Burke, E., 174, 190 Bushy samphir, as alkali indicator, 63, 66 Butt, N. I., 151, 237 Buttercup, as alkali indicator, 64 Cairo, rainfall of, no Calcium : carbonate hardpan, 124 chloride, solubility, 105 determination of, 92 effect on salts, 116 sulphate antagonistic with so- dium sulphate, 115 sulphate, solubility, 105 Caldwell, J. S., 116, 117 California: alkali in, 8, 9 method of alkali analysis, 84, 85 sodium sulphate experiments, 108 Cameron, F. K., 20, 22, 28, 32, 44, 46, 104, 113, 118, 124, 131, ISO. 151 Camphor tree, 221 Canada, alkali in, 7 Canadian soils, 114 Canal lining, 32 Capillarity affected by alkali, 128 Carbonates: determination of, 86 effect on capillarity, 128 source of, 28 Carrying capacity of drains, 180 Carter, E. G., 136, 139 INDEX 249 Catlin, C. N., 104 Cause of hardpan, 123 Celery, 217 Cell: effect of alkali on, 35 sap concentration, 35 Cement drain tile, 174 Changing soil structure, 119 Chemical: equilibrium, 105 methods of determining alkali, 81 treatments for alkali, 161 Chezy-Kutter formula, 179 Chili, soluble salt deposits in, 10 Chloride: determination, 88 effect on capillarity, 130 Clarke, F. W., 14, 18, 20, 32 Clovers, 200 Code, W. W., 238 Coe, H. S., 199, 221 Colloids, effect of alkali on, 122 Colorado, alkali in, 8, 9 Comparison of analytical methods, Composition of: alkali in judging land, 243 alkali waters, 231, 232 earth's crust, 18 hardpan, 127 lithosphere, 17 ocean water, 18 rocks, 16, 17 soil-forming minerals, 17 Conner, S. D., 221 Construction methods, 183 Contamination: source of, 154 of irrigation water, 225 Copper, effect on salts, 116 Corn, 214 Cost of drainage, 189 Cotton, 218 Cottonwood, 221 Coupin, H., 46, 48, 58 Cowslip, as alkali indicator, 64 Crawley, J. T., 238 Crepis, as alkali indicator, 64 Cressa, as alkidi indicator, 63, 70 Cretacious deposits, 23 Crimson clover, 200 Cropping in reclamation, 162 Crops for alkali land, 192 Crust, effect on evaporation, 157 Cultivation to reduce evajjoration, 154 D Dakota formation, 23, 24 Date palms, 219 Davis, R. O. E., 104, 121, 128, 131 Davy, J. B., 60, 80 Deakin, A., 14 Decomposition of rocks, 19 Deflocculation of soil by alkali, 121 De Greef, H., 220 Demoussy, E., 118 Description of alkali-indicating plants, 74 Desolation, caused by alkali, 3 Determination of: alkali, 81 bases, 92 bicarbonatcs, 86 calcium, 92 carbonates, 86 chloride, 88 magnesium, 93 nitrate, 89 sodium, 93 sulphiUe, 89 total solids, 86 Determining need of drainage, 170 Dieckman, G. P., 176, 190 Dimo, N. A., 15, 146, 151 Dissolved matter washed to sea, 19 250 INDEX Distribution of alkali, 6 Dorscy, C. W., 20, 32, 147, 148, 151, i66, 221, 238 Drain outlets, 188 Drainage: advantages of, 167, 169 cost of, 189 for reclamation 162, 167 machines, 186, 187 Drains: carrying capacity of, iSo size of, 178 types of, 171 Duggar, B. M., 40 Dwarf samphir, as alkali indicator, 63,66 Dymond, T. S., 213, 221 Dynamite in breaking hardpan, 123 Earth's crust, composition of, 18 Eaton, F. M., 239 Eckart, C. F., 221, 23S Economic factor in: crop choice, 195 judging land, 243 Efifect of: alkali on: ammonification, 13S bacteria, 132 capillarity, 128 colloids, 122 germination, 36 nitrogen fixation, 137 plant structure, 38 soil tilth, 120 surface tension, 128 salts on: evaporation, 13c moisture movement; 128 soil organisms on sterility, 133 water-table, 145 Egypt, alkali in, 10, tt Egyptian: clover, 200 millet, 208 Electric bridge method, 94 Emmer, 214 English rye grass, 204 Equilibrium : chemical, 105 in soil solution, iii EucaljT^tus, 220 Europe, alkali in, 13 Evaporation : of moisture, 130 of saline lakes, 27 reduction of, 155 Experiments: in loam, 53 in sand, 49 with rice, 114 with sodium sulphate in Calif., 108 Extract of soil, 81 Factors affecting resistance, 192 Failyer, G. H., 82, 104 False golden rod, as alkali indicator. 73 Fescue, 204 Fiber crops, 218 Field peas, 200 Flax, 218 Flocculation of soil, effect of alkali, 121 Flooding to reclaim land in Egyi)t, 160 Forage crops, 197 Forbes, R. H., 229, 238 Formation of: black alkali, loS carbonates, 28 hardpan, 123 nitrates, 30 INDEX 251 Formation of: sodium bicarbonate, io6 Formula for Mass Action, 106 Fowler, T. W., 134, 139 Fraps, G. S., 237, 238 Freak, G. A., 102, 103 Free, E. E., 121, 131 Freezing-point method of anal} sia. 102 Fruit trees, 219 Fulaykov, N., 23S Fungi in soil and fertility, 133 Gandcchon, II., 152 Gardner, F. D., 123, 124, 131, 197, 238 Gedroits, K.. K., 22, 29, 32, 131 Geographical distribution of alkali, 6 Geology in judging land, 240 Gericke, W. F., 115, 118, Germination: effect of alkali on, 36 experiments, 44 Giant r>'e-grass, 207 Gila River water, 225 Glaux, as alkali indicator, 64 Golden willow, 221 Goldthorpe, H. C, 136, 139 Grade of drain, 177 Goosefoot, as alkali indicator, 64 Grain crops, 210 Grapes, 220 Grasses, 2co Greasewood, as alkali indicator, 63, 6S Great Basin, alkali in, 8 Greaves, J. E., 22, 33, 91, 103, 104, 136, 138, 139, 238 Green River formation, 27 Gutlirie, F. B., 55, 56, 58, 229, 23S Gypsum: for black alkali, 160 leaching of, 129 H Hall, A. D., 120, 131 Hansen, D., 142, 151, 222 Hansteen, B,, 48, 58, 117 Hardpan, 122 Hare, R. F., 84, 104, 150, 151 Harris, F. S., 32, 40, 53, 58, 118, 130, 131, 151, 152, 158, 166, 203, 222, 237 Hart, R. A., 1C5, 166, 174, 179, 189, 190 llarter, L. L., 38, 40, 59 Haselhoff, E., 48, 54, 58 Headden,\V. P., 32, 57, 142, 145, 146, 152, 161, 166, 176, 190, 211, 215, 222, 238 Headley, F. B., 222 Hebert, A., 15 llecke, E., 220, 222 Ileime, C, 220 Hcileman, W. H., 127, 131 Helms, R., 55, 56, 5S Hicks, G. H., 40, 46, 58 Ililgard, E. W., 9, 15, 32, 40, 69, So, 121, 123, 131, 144, 147, 152, 158, 160, 166, 197, 207, 217, 222, 229, 238 Hill, E. G., IS Hills, T. L., 137, 139 Hirst, C. T., 91, 104, 238, 239 Ilissink, D. J., 152 Hitchcock, E. B., 136, 139 Holmes, J. G., 212, 222 Houston, D., 213, 221 Hungary', alkali in, 13 Imperial Valley, alkali in, 8 Inactivity of organisms and soil steriUty, 133 India, alkali in, 13 Indicating plants, description of, 74 Indicator value of vegetation, 60 252 INDEX Injury, nature of, 34 Inkweed, as alkali indicator, 63, 65 Irrigation: systems in Egypt, 12 water, 224 water, carrier of alkali, 30 water, composition of, 231, 232 water, toxic limits, 22S weed, as alkali indicator, 63, 73 Isham, R. M., 3a, 33 Italian r>'e grass, 204 Italy, alkali in, 13 J Japanese wheat grass, 203 Jcffery, J. A., 190 Jensen, C. A., 80, 211, 212, 215, 222, 239 Joffa, M. B., 118 Johnson, D. R., 138, 139 Jost, L., 40 Judging alkali land, 240 Jurassic deposits, 23 Kearney, T. H., 15, 39, 40, 44, 46, 47, 58, 59, 80, 113, 118, 197, 199, 200, 201, 202, 203, 204 205, 208, 210, 212, 213, 214, 217, 218, 221, 222 Kcllerman, K. F., 122, 131 Kclley, W. P., 29, 32, 118, 135, 137, 139 Kern greasewood, as alkali indi- cator, 63, 66 King, F. H., 82, 146, 152, 190 Klein, M. A., 139 , Knight, W. C, 32, 118 Knop's solution, 43 Kochia, as alkali indicator, 63, 72 Kolotov, G. I., 152 Kolreuteria, 220 Kossovich, P., 59, 144, 152, 238 Kravkov, S., 152 Kuiiper, J., 239 Lakes, saline, 27 Land : judging, 240 method of reclaiming, 154 Lapman, M. H., 128, 129, 144, 151 Law of Mass Action, 106 Laying out system, 177 Leaching of gypsum, 129 Leather, J. W., 14, 15 Leaves to reduce evaporation, 157 Le Clerc, J. A., 43, 50, 54, 59, 117 Legumes, 200 Lemon, 220 Lcsage, P., 59 Lime, corrective for magnesium, 114 Limestone, composition of, 17 Lining of canals, 32 Limit of biological activity, 335 Limits, toxic, 42 Linsley, J. D,, 166 Lipman, C. B., 103, 115, 118, 134, 13s, 137, 139, 161, 166 Lippincott, J. B., 239 Lithosphere, composition of, 17 Little rabbit brush, as alkali indica- tor, 63, 73 Loam, experiments in, 53 Loughbridge, R. H., 121, 131, 147, 152, 160, 166, 200, 201, 203, 204, 206, 208, 209, 211, 212, 214, 217, 222 Lumber drains, 180, 184 M Mackie, W. W., 80, 142, 145, 147, 152, 212, 229, 239 MacOwan, P., 15 INDEX 253 Magnesium: determination of, 93 chloride, solubility, 105 corrected by lime, 114 sulphate, solubility, 105 Magowan, Florence N., 44, 59 Mancos shale, 24, 25, 26, 27 Manhole for drain, 189 Mann, H. H., 15 Marchal, E., 48, 59, 140 Marquenne, L., 118 Marsh grass, as alkali indicator, 64 Masoni, G., 121, 131 Mass Action, 106 McCool, M. M., 102, 103, 142, 152 McLane, J. W., 80 Mead, C. E., 222 Meade, R. K., 175, 190 Meadow fescue, 204 Meaning of alkali, 5 Means, T. H., 12,15, i>^) 22, 33, 160, 166, 197, 239 Merrill, G. P., 18 Mesopotamia, alkali in, 13 Method: electric bridge, 94 of reclaiming alkali land, 154 Methods: comparison of, 85 of constructing drains, 183 of determining alkali, 81 Micheels, H., 40, 45, 59 Microorganisms, effect of alkali on, 132 Miller, C. E., 142, 152 Millets, 208 Minerals: alkali in, 19 in rocks, 16 Miyake, K., 59, 114, 118 Montana: alkali in, 9 formation, 25 Montana: method of alkali analysis, 84, 85 Moisture: evaporation, 130 movements, 128 Modiola, 206 Morocco, alkali in, 10 Mousetail, as alkali indicator, 6 Movement of: alkali with water, 142 moisture, 128 salt, rate of, 148 soluble salts, 141 various salts, 146 Mulch to reduce evaporation, 154 Mulberr>', 220 Munter, E., 138 Muntz, A., 152 Myers, H. C., 80 N Native: grasses, 205 vegetation as alkali indicator, 60,63 vegetation in judging land, 242 Nature of alkali injury, 34 Need of drainage, 170 Neill, N. P., 199, 201, 222 Nelson, A., 208, 222 Neutralizing sodium carbonate, 160 Newell, F. H., 239 Nile River Valley, alkali in, 11, 12 Nitrate: determination, 89 formation, 30 Nitrates, eflect on capillarity, 129 Nitric acid for alkali land, 161 Nitrogen fixation, effect of salts on, 137 North America, alkali in, 6 Nutrient solutions, 43 254 INDEX O Oat-grass, 204 Oats, 213 O'Brien, D., 239 Ocean: as source of alkali, 21 water, 18 Olives, 220 Onions, 217 Open drain, 172 Orange, 220 Orchard: grass, 202 killed by alkali, 39 Organisms and soil fertility, 132 Origin of: alkali, 16 hardpan, 123 Osterhout, W. J. V., 117, iiS Otto, R., 239 Oudh Province, alkali in, 13 Outlets, 188 Plasmolysis of cell, 35 Plowing under alkali, 158 Plowmans' wort, as alkali indicator, ,64 Pomegranate, 221 Poplars, 221 Poncelet's formula, 178 Port Said, rainfall of, 11 Potatoes, 216 Practical drainage, 167 Prairie grass, 206 Precipitation records, 11 Preliminary survey, 1 76 Preparing solution of soil, 81 Prevention of water absorption, 34 Proso millet, 208 Prune, 220 Puchner, II., 144, 152 Punjab, alkali in, 13 Purple top: as alkali indicator, 63 grass, 206 Px-rrocoma, as alkali indicator, 64 Pagnoul, A., 149, 152 Parson, J. L., igo Patten, H. E., 150, 151, 152 Peach, 220 Pear, 220 Peas, 200 Peimersel, R. L., 80 Pepper grass, as alkali indicator, 64 Persia, alkali in, 13 Peterson, Wm., 22, 30, 33 Pfeffer, W., 36, 41 Phillips, A. J., 190, 191 Phosphates, effect on capillarity, 12S Physical condition of scil, 119 Pigweed, as alkali indicator, 64 Pinckney, R. ]\I., 174, 190 Pittman, D. W., 53, 104, 203, 222 Plant descriptions, 74 Plants as indicators of alkali, 60, 63 Quantity of salts to reduce yields, 56 R Rabbitt brush, as alkali indicator, 63, 73 Radishes, 217 Rape, 209 Rate of alkali movement, 14S Reclamation: by cropping, 162 methods, 154 system in Egj'pt, 12 Red clover, 200 Red top, 203 Reduced jdelds from salts, 56 Reducing evaporation, 155 Reh commission, 13, 14 Reh lands, 13 INDEX 255 Relation of: alkali to biological conditions, 132 alkali to physical conditions, 119 Removing salts from surface, 159 Resistance : factors afJecting, 192 tables, 96 Resistant crops in reclamation, 162 Revicl, 59 Rhodesia, alkali in, 10 Rice, 214 experiment with, 114 Robinson, J. S., 130, 131, 151, 158, 166 Rock, composition of, 16 Rolct, A., 160, 166 Root: crops, 215 zone increased by drainage, 169 Roots injured by alkali, 34 Rushes, 20S Rush, as alkali indicator, 64 Russian olive, 221 Rye, 214 grass, 204 Sachsse, R., 120, 131 Sackett, W. G., 30, ;^^, 140 Sage brush as indicator of land, 242 Sahara, soib of, 10 Saline lakes, 27 Salt: bushes, 207 bush as alkali indicator, 63, 70 crvjst, relation to evaporation, 157 grass, 205 grass, as alkali indicator, 63, 73, 243 movement with water, 142 Salt: River water, 225 wort, as alkali indicator, 63. Salts: absorption by soils, 109 antagonism between, 113 by bridge method, 94 by freezing-point method, 102 effected by calcium, copper, zinc, 116 effect of, on moisture move- ment, 128 from ancient seas, 22 in hardpan, 127 in natural soil, 141 movement of, 14, 146 plowing under of, 158 quantity to reduce yields, 56 removal from surface, 159 removed in drainage, 163, 164 soluble in water, 105 solubility of, 106 Samphire, as alkali indicator, 63 Sanchez, A. M., 198, 222 Sand, experiments in, 49 Sandsten, E. P., 166 Sandstone, composition of, 16, 18 Saskatchewan, alkali in, 7 San Joaquin Valley, alkali in, 8 Schreiner, O., 82, 104 Scofield, C. S., 239 Sedger, 208 Seed germination experiments, 44 Shading to reduce e\'aporation, 157, 158 Shadscale, as alkali indicator, 63, 70 Shale, composition of, 16, 17 Shantz, H. L., 80 Sharp, L.T., 115, 118, 131, 137, 148, 149. 153 Shaw, G. W., 15 Shinn, C. H., 152, 160, 166 Shooting star, as alkali indicator, 64 256 INDEX Shrubs, 218, 219 Shutt, F. T., 8, 15, 54, 59, 118, 204, 206, 211, 212, 217, 223 Sigmond, A., von, 15, 45, 59 Silt basins, 188 Sims, C. E., 90, 176 Size of drains, 178, 181, 182 Skinner, W. W., 104 Slossom, E. C, 32, 40, 45, 51, 59, 239 Smith, E. A., 15, 206, 211, 223 Smith, J. G., 222 Snow, F. J., 15 Sodium: determination of, 93 bicarbonate, formation of, 106 carbonate: hardpan, 127 neutralizing of, 160 solubility, 105 chloride, solubility, 105 nitrate, solubility, 105 sulphate, experiments in Cali- fornia, 108 sulphate, solubility, 105 Soil: analysis of, 12 bacteria, antagonistic results with, 116 composition in judging land, 243 extract, 81 fertility and organisms, 132 indicated by plants, 60 movement of alkali through, 141 organisms and fertility, 132 physical condition of, 119 solution, equilibrium in, iii solution, preparation of, 81 solution, variance in concentra- tion, 112 warmed by drainage, 169 sterility and organisms, 133 Soils: absorption of salts, 109 Canadian, 114 Solids, determination of, 86 Soluble : salt movement with water, 142 salts, movement of, 141 salts by bridge, 94 salts in hardpan, 127 Solubility: affected by temperature, 105, 109, 112 of salts, 105, 106 Solution: experiments, 44 Knop's, 43 nutrient, 43 preparation of, 81 Solutions: alkali, 44 nutrient, 43 toxicity of, 43 Sorghums, 208 Source of: alkali determines methods, 154 contamination, 154 Sources of water contamination, 225 South Africa, alkali in, 10 South America, alkali in, 10 Spike weed, as alkali indicator, 63, 73 Stabler, H., 239 Strahorn, A. T., 80, 211, 215, 239 Steik, K., 176, 190 Stevenson, W. H., 15 Stewart, J., 51, 123, 124 Stewart, R., 22, 30, S3, io4, 239 Straw to reduce evaporation, 157 Structure of: plants affected by alkali, 38 soil, 119 Sugar-beets, 215 Sulphate determination, 89 INDEX 257 Sulphuric acid: beneficial, ii6 treatment for alkali, i6i Sunflowers, 214 Surface: removal of salts from, 159 tension affected by alkali, 128 Survey for drains, 1 76 Swan tract, reclamation of, 162 Sweet clover, 199 Sycamore, 220 Symmonds, R. S., 161, 166 Szik lands, 13 Table of solubility of salts, 105 Tables of electrical resistance, 96 Tall meadow oat-grass, 204 Tamarisk, 221 Tamhane, V. A., 15 Taylor, C. S., 133, 140 Temperature, effect on salt solu- bility, 105, 109, 112 Tertiary formation, 26, 27 Texas method of alkali analysis, 84, 85 Tilth of soil, effect of alkali on, 120 Timothy, 202 Tolerance of various crops to alkali, 196 Torpedo drain, 173 Total solids, determination of, 86 Tottingham, W. E., 44, 59, 222 Toxicity of: salts alone, 43 solutions, 43 Toxic limits: for bacteria, 135 of alkali, 42 Trailing buttercup, as alkali indi- cator, 64 Transpiration reduced by salts, 34 Traphagen, F. W., 15, 22, 33, 202, 212, 213, 222 Treatment of alkali affected by origin, 31 Treatments for alkali, chemical, 161 Trees, 218 Treitz, P., 29, ^^ True, R. H., 41, 48, 59 Tuber bulrush, 64 Tulaykov, N., 15, 143, 153 Tunis, alkali in, 10 Turkestan, alkali in, 13 Tussock grass, 206 as alkali indicator, 63, 65 Types of drains, 171 U United States, alkali in, 8 Usar lands, 13, 14 Utah: alkali in, 8 method of alkali analysis, 84, 85 Valeria, as alkali indicator, 64 Van Winkle, W., 239 Vapor tension reduced by salts, 130 Variance of soil solution concentra- tion, 112 Variation in composition of water, 234 Vegetables, 215 Vegetation as alkali indicator, 60, 63 Vetch, 200 Vinson, A. E., 104 Vissotski, G., 15 Vreis, H. de, 36, 44 W Waggaman, W. H., 152 Warington, R., 146, 148, 153 Washington, alkali in, 9 Washingtonia palm, 221 258 INDEX Water: absorption, prevention of, 34 composition of, 231, 232 for irrigation, 224 from Gila River, 225 from Salt River, 225 from various rivers, 226, 227, 228 supply increased by drainage, 169 -table, effect of, 145 -table, effect of on evaporation, 158 _ -table in judging land, 243 toxic limits, 228 Weed, H. H., 22 Weir, W. W., 166, 188, 191 Western wheat grass, 203 Wheat, 210 White sage, as alkali indicator, 63, 72 Whitney, M., 18, 22, 33 Widtsoe, J. A., 239 Wig, R. J., 190, 191 Wild grasses, 205 Wiley, H. W., 104 Willcocks, W., 15, 191, 239 Wohltman, F., 239 Wyoming, alkali in, 8 Yields reduced by salts, 56 Yohe, H. S., 191 Zinc, effect on salts, 116