s 
 
 533 
 
 U. S. DEPARTMENT OF AGRICULTURE. 
 BUREAU OF PLANT INDUSTRY— BULLETIN NO. 211. 
 
 B. T. GALLOWAY, Chief of Bureau. 
 
 BACTERIOLOGICAL STUDIES OF THE SOILS OF 
 
 THE TRUCKEE-CARSON IRRIGATION 
 
 PROJECT. 
 
 KART. P. KELLERMAN, 
 Physiologist in Charge of Soil-Bucterlology and Wutcr-Purlficalion Investigations, 
 
 AND 
 
 E. R. ALLEN, 
 Scientific Assistant. 
 
 IssuEu April 15, 1911. 
 
 
 WASHINGTON: . 
 
 GOVERNMENT PRINTING OFFICE. 
 
 1911. 
 
Qass. 
 Book. 
 
 S 533 
 
 .K5 
 
U. S. DEPARTMENT OF AGRICULTURE. 
 
 BUREAU OF PLANT INDUSTRY— BULLETIN NO. 211. 
 
 B. T. GALLOWAY, Chief of Bureau. 
 
 BACTERIOLOGICAL STUDIES OF THE SOILS OF 
 THE TRUCK EE-CARSON IRRIGATION 
 
 PROJECT. Ji9 
 
 792 
 
 KARL f[ KELLERMAN, 
 
 Physiologist in Charge of Soil-Bacteriology and Water-Purijication Investigations, 
 
 AND 
 
 E. R. ALLEN, 
 
 Sdentijic Assistant. 
 
 Issued April L5, I'JIL 
 
 WASHINGTON: 
 
 GOVERNMENT l'KINTIN(i OFFICE. 
 1911. 
 
 G 
 
 Ti 
 

 BUREAU OP PLANT INDUSTRY. 
 
 Chief of Bureau, Beverly T. Galloway. 
 Assistant Chief of Bureau, VfiLUAyi A. Taylor. 
 Editor, J. E. Rockwell. 
 Chief Clerk, James E. Jones. 
 
 sell-bacteriology and w ater-purification investigations. 
 Scientific Staff. 
 Karl F. Kellerman, Physiologist in Charge. 
 T. R. Robinson, Assistant Physiologist. 
 
 I. G. McBeth, E. R. Allen, R. C. Wright, and Edna H. Fawcett, Scientific Assistants. 
 F. L. Goll and L. T. Leonard, Laboratory Aids. 
 211 
 2 
 
 ]2]] 
 
LE^n^ER OF TRANSMITTAL 
 
 U. S. Department of xioRicuLTURE, 
 
 Bureau of Plant Industry, 
 
 Office of the Chief, 
 Washington, D. C, January 17, 191 L 
 Sir: I have the honor to transmit herewith a paper entitled ''Bac- 
 teriological Studies of the Soils of the Truckee-Carson Irrigation 
 Project" and to recommend that it be published as Bulletin No. 211 
 of the series of this Bureau. 
 
 These investigations, though in many ways of a preliminary char- 
 acter, indicate some of the possibilities of a bacteriological diagnosis 
 of soils and will be of interest to all- who have to deal with problems 
 of soil fertility. 
 
 Respectfully, Wm. A. Taylor, 
 
 Acting Chief of Bureau. 
 Hon. James Wilson, 
 
 Secretary of Agriculture. 
 211 3 
 
CO NTH NTS, 
 
 Page. 
 
 Introduction 7 
 
 Methods employed in bacteriological investigations of the soil at Fallon, Nev. . 8 
 
 Requirements to be met 8 
 
 founts of bacteria 9 
 
 Ammonification 9 
 
 Nitrification 10 
 
 Denitrification 11 
 
 Nitrogen fixation 11 
 
 Nitrifying power of soils at different depths 12 
 
 Nitrification of samples in solution 19 
 
 Chlorids and sulphates 21 
 
 Denitrification 22 
 
 Relative numbers of bacteria in different soils 24 
 
 Detailed study of soil typical of extensive areas 25 
 
 Conclusions 32 
 
 Index 35 
 
 ILLUSTRATIONS. 
 
 Page. 
 Fig. 1. Location of sampling plats in the experimental fields of the Truckee- 
 
 Carson Experiment Farm, south of Fallon, Nev 8 
 
 2. Diagram showing the nitrification of ammonium sulphate in samples of 
 
 soil from different depths from plats 100 and 110, Truckee-Carson 
 Experiment Farm 12 
 
 3. Diagram showing the nitrification of ammonium sulphate in samples of 
 
 soil from different depths from plat 120, Truckee-Carson Experiment 
 Farm 13 
 
 4. Diagram showing the nitrification of ammonium sulphate in samples of 
 
 soil from different depths from plat 130, Truckee-Carson Experiment 
 Farm 13 
 
 5. Diagram showing the nitrification of ammonium sulphate in samples of 
 
 soil from different depths from plats 160 and 170, Truckee-Carson 
 Experiment Farm 14 
 
 6. Diagram showing the nitrification of ammonium sulphate in samples of 
 
 soil from different depths from plat 180 (poor soil) and plat 190 (good 
 soil), Truckee-Carson Experiment Farm 15 
 
 7. Diagram showing the nitrification of ammonium sulphate in samples of 
 
 soil from different depths from plat 200, Truckee-Carson Experiment 
 Farm 16 
 
 8. Diagram showing the nitrification of ammonium sulphate in samples of 
 
 soil from different depths from plat 210, Truckee-Carson Experiment 
 
 Farm 16 
 
 211 5 
 
6 ILLUSTRATIONS. 
 
 Page. 
 Fig. 9. Diagram showing the nitrification of ammonium sulphate in samples of 
 soil from different depths from plat 220, Truckee-Carson Experiment 
 Farm 17 
 
 10. Diagram showing the nitrification of ammonium sulphate in samples of 
 
 soil from different depths from plat 230, Truckee-Carson Experiment 
 Farm 17 
 
 11. 1 )iagram showing the nitrification of ammonium sulphate in samples of 
 
 soil from different depths from plats 240 and 250, Truckee-Carson 
 Experiment Farm IS 
 
 12. Diagram showing the nitrification of ammonium sulphate in samples of 
 
 soil from different depths from plats 260 and 270, Truckee-Carson 
 Experiment Farm 19 
 
 13. Diagram showing the nitrification of ammonium sulphate in samples of 
 
 •soil from different depths from plats 280 and 290, Truckee-Carson 
 Experiment Farm 20 
 
 14. Diagram showing the relation between the quantity of alkali and the 
 
 nitrification in samples of soil from plats 180, 190, 170, 150, 100, 160, 
 110, and 120, Truckee-Carson Experiment Farm. Samples taken 
 from depths of to 6 inches 21 
 
 15. Diagram showing the relation between the quantity of alkali and the 
 
 nitrification in samples of soil from plats 180, 120, 170, 100, 190, 150, 
 160, and 110, Truckee-Carson Experiment Farm. Samples taken from 
 depths of 6 to 12 inches 22 
 
 16. Diagram showing the relation between the quantity of alkali and the 
 
 nitrification in samples of soil from plats 180, 190, 170, 100, 120, 160, 
 110, and 150, Truckee-Carson Experiment Farm. Samples taken 
 from depths of 12 to 18 inches 23 
 
 17. Diagram showing the relation between the quantity of alkali and the 
 
 nitrification in samples of soil from plats 180, 170, 190, 100, 110, 160, 
 150, and 120, Truckee-Carson Experiment Farm. Samples taken 
 from depths of 18 to 24 inches 23 
 
 18. Diagram showing the effect of calcium sulphate upon the nitrification 
 
 of ammonium sulphate in samples of soil from plat 300, Truckee-Carson 
 Experiment Farm, representing poor soil "A;" plat 310, representing 
 poor soil "B;" and plat 320, representing good soil 29 
 
 19. Diagram showing the ammonification of peptone in 7 days in samples of 
 
 soil from plat 350 (good soil) and from plats 330 and 340 (poor soil), 
 Truckee-Carson Experiment Farm 30 
 
 20. Diagram showing the ammonification of peptone in 15 days in samples 
 
 of soil from plat 350 (good soil) and from plats 330 and 340 (poor soil), 
 
 Truckee-Carson Experiment Farm 31 
 
 211 
 
B. P. I.— 646. 
 
 BACTERIOLOGICAL STUDIES OF THE SOILS OF THE 
 TKUCKEE-CARSON IRRIGATION PROJECT. 
 
 INTRODUCTION. 
 
 In making a bacteriological study of any soil or group of soils there 
 are certain fairly well defined groups of micro-organisms whose func- 
 tions, although as yet imperfectly understood, are recognized as im- 
 portant factors in crop production and are more or less familiar to 
 everyone who has attempted to investigate the problems of soil 
 fertility. These groups of micro-organisms may be roughly separated 
 into four classes, depending upon their physiologic characteristics: 
 (1) Parasites, or organisms important chiefly because they are patho- 
 genic to animals or plants and are frequently found in soils; (2) the 
 cellulose-destroying organisms ; (3) the organisms associated with the 
 formation of humus; and (4) the organisms associated with the trans- 
 formation of soil nitrogen. Only those groups concerned with the 
 transformation of nitrogen, which in the form of ammonia or nitrate 
 is practically the most important of all plant foods, are reported upon 
 at this time. 
 
 The data sought in studies of this character may be outlined as 
 follows: 
 
 (1) Total numbers of saprophytic bacteria in measured quantities of soil. 
 
 (2) Ammonification ; the breaking down of nitrogenous organic matter into ammonia. 
 
 (3) Nitrification; the oxidation of various compounds of nitrogen to nitrate. 
 
 (4) Denitrification; the reverse of nitrification. 
 
 (5) Nitrogen fixation, symbiotic and nonsymbiotic; the utilization of atmospheric 
 nitrogen in forming nitrogenous organic compounds. 
 
 In the work conducted at Fallon, Nev., during the season of 1909, 
 in cooperation with the Office of Western Agricultural Extension, no 
 quantitative study was made of nitrogen fixation, and the data on the 
 subject of ammonification are very meager. Some preliminary inves- 
 tigations in arid regions had shown that nitrification takes place here 
 at considerable depth. All studies, therefore, were made of a 3-foot 
 zone, keeping separate the samples of soils from different depths. 
 
 The comparative nitrifying power of the different samples from the 
 various plats is shown by curves, the parts per million of nitrogen as 
 nitrate and nitrite being plotted as ordinates, and the different depths 
 as abscissae. These curves show only the gain in nitric and nitrous 
 nitrogen. Chlorids and sulphates are also shown, but seem to be of 
 
 211 7 
 
8 
 
 SOILS OF THE TRUCKEE-CAKSON IRRIGATION PROJECT. 
 
 little importance. The quantity of nitric nitrogen originally present 
 is shown in the legends under the diagrams (figs. 2-13). 
 
 A description of the Truckee-Carson Experiment Farm, at Fallon, 
 Nev., upon which practically all of the work herein reported was con- 
 ducted, is given in a previous bulletin of this Bureau.^ Tlie designa- 
 tions of the small plats from which samples were taken for bacterio- 
 logical study and their location are shown in figure 1 . 
 
 Fig. 1.— Location of sampling plats in the experimental fields of the Truckee-Carson Experiment 
 
 Farm south of Fallon, Nev. 
 
 METHODS EMPLOYED IN BACTERIOLOGICAL INVESTIGATIONS 
 OF THE SOIL AT FALLON, NEV. 
 
 REQUIREMENTS TO BE MET. 
 
 Investigations in soil bacteriology require first of all the selection 
 and development of satisfactory methods for determining the dis- 
 tribution and activity of the micro-organisms which may occur under 
 
 ' Scofield, C. S., and Rogers, S. J. The Truckee-Carson Experiment Farm. Bul- 
 letin 157, Bureau of Plant Industry, 1909. 
 211 
 
METHODS EMPLOYED IN BACTERIOLOGICAL INVESTIGATIONS, 9 
 
 different soil conditions. Though it is recognized that the methods 
 suggested by different investigators are not adequate for accurate 
 quantitative investigations of bacterial functions and conditions in 
 various soils, the methods which at this time have been found most 
 convenient and suitable for the investigations under discussion are 
 briefly reviewed.^ 
 
 COUNTS OF BACTERIA. 
 
 Samples of soil were collected with as strict aseptic precautions as 
 it is possible to observe under field conditions. Sterile salt-mouth 
 bottles were used as containers, and the soil auger used for taking up 
 the soil was carefully cleaned and flamed over an alcohol lamp before 
 sampUng each stratum. In the laboratory 1-gram portions were 
 removed from the bottles with a sterile scoop wliich held the required 
 quantity, transferred to 300 cubic centimeters of sterile water in 
 500-cubic-centimeter flasks, and the whole shaken thoroughly at short 
 intervals for fifteen minutes. One-cubic-centimeter portions of these 
 infusions were then removed with sterile pipettes and added to 10 
 cubic centimeters of melted beef agar, and plates poured in the ordi- 
 nary manner and incubated at 28° C. Counts of bacteria were made 
 at the end of five-day periods. 
 
 AMMONIFICATION. 
 
 Sterile peptone solutions having the following composition were 
 inoculated with 5 per cent of soil and the ammonia determined at the 
 end of seven and fifteen days by distillation with magnesia: 
 
 Peptone 15 grams. 
 
 Dipotassium phosphate 3 grams. 
 
 Magnesium sulphate 3 grams. 
 
 Sodium chlorid 3 grams. 
 
 Water ] , 000 c. c. 
 
 ^ Lipman, J. G. Experiments on the Transformation and Fixation of Nitrogen by 
 Bacteria. Twenty-fourth Annual Report, New Jersey State Agricultural Experiment 
 Stations, 1903, pp. 217-285. 
 
 Lipman, J. G., and Brown, Percy E. Methods Concerning Ammonia Formation 
 in Soils and Culture Solutions. Report, Soil Chemist and Bacteriologist, New Jersey 
 Agricultural College Experiment Station, 1908, pp. 95-105. 
 
 Lipman, J. G., and Brown, Percy E. Notes on Methods and Culture Media. Report, 
 Soil Chemist and Bacteriolflgist, New Jersey Agricultural College Experiment Station, 
 1908, pp. 129-136. 
 
 Lipman, J. G. Azotobacter Studies. Report, Soil Chemist and Bacteriologist, 
 New Jersey Agricultural College Experiment Station, 1908, pp. 137-143. 
 
 Lohnis, F. Ein Beitrag zur Methodik der bakteriologischen Bodenuntersuchung. 
 Centralblatt fiir Bakteriologie, Parasitenkunde und Infektionskrankheiten, pt. 2, 
 vol. 12, no. 6-8, pp. 262-267, June 24, 1904; no. 11-16, pp. 448-463, July 14, 1904; 
 vol. 17, no. 14-16, pp. 518-528, December"?, 1906; vol. 20, no. 24-25, pp. 781-799, 
 April 15, 1908; vol. 24, no. 5-7, pp. 183-192, August, 1909. 
 
 Remy, Theodor. Bodenchemische und Bakteriologische Studien. Landwirt- 
 schaftliche Jahrbiicher, vol. 35, Supplement 4, pp. 1-62. Berlin, 1906. 
 78011°— Bui. 211—11 2 
 
10 SOILS OF THE TEUCKEE-CARSON IKRIGATION PROJECT. 
 
 NITRIFICATION. 
 
 Samples of soil were collected with the precautions previously 
 described. In some cases 1-gram portions for counts of total num- 
 bers of bacteria were removed from the bottle of soil and the remainder 
 of the sample used for nitrification studies. 
 
 Because of the great variation in the fertilty of different fields it 
 was considered necessary to determine at what depths the nitrifying 
 bacteria existed; therefore, instead of emptying the soil from the 
 container and allowing it to dry, thus exposing it to some contamina- 
 tion, one-half of the soil, approximately 50 grams, was removed with 
 a sterile spatula and used for "original" determinations. Five cubic 
 centimeters of 0.4 per cent ammonium sulphate was then added to the 
 portion remaining in the bot Je and the sample placed in the incu- 
 bator at 28°C. With the original moisture of the soil this additional 
 5 cubic centimeters frequently made the water content of the soil 
 somewhat above optimum, but owing to the rapid evaporation in an 
 arid climate this rapidly decreased and was adjusted as nearly as 
 possible in subsequent waterings. All samples were weighed at S-da}^ 
 intervals, and as any appeared to fall below optimum the required 
 quantity of sterile distilled water was added to restore them. The 
 incubation period was two weeks, the temperature being maintained 
 at 28°C. 
 
 The chemical work presented no little difficulty. The analytical 
 determinations may be considered in two phases: (1) The prepara- 
 tion of the aqueous extract of the soil both before and after incuba- 
 tion with ammonium sulphate and (2) the determination of nitrites 
 and nitrates in original and incubated samples. 
 
 In the preparation of the aqueous extract considerable difficulty 
 was experienced. AU of the soils used contained variable and fre- 
 quently quite large proportions of very fine clay, which would not 
 settle out and leave a clear supernatant liquid, even on prolonged 
 standing. It was thought advisable to determine the chlorids and 
 sulphates in the original samples; therefore the common salts con- 
 taining these radicals could not be used to flocculate the clay, 
 although this method was sometimes used in the examination of the 
 samples after incubation where only nitrites and nitrates were deter- 
 mined. Pressure-pump facilities were inadequate for the large num- 
 ber of samples used, the more so as the fine clay particles clogged the 
 porcelain filter and caused filtration to be extremely slow with the 
 low pressure available.* Heating the sample in the oven at different 
 temperatures previous to adding the water seemed to have no effect, 
 so the supernatant liquid was first drawn off turbid, evaporated to 
 dr;yness, baked at 90° to 100° C, and then filtered. In all of the 
 
 ' Approximately 25 pounds to the square inch. 
 211 
 
METHODS EMPLOYED IN BACTEKIOLOGICAL INVESTIGATIONS. 11 
 
 baking experiments it was noticed that the nearer a set of samples 
 was baked at 100° C. the better the subsequent filtering, probably 
 indicating that the clay is siliceous. 
 
 The Griess method is the standard for determining nitrites, but 
 owing to the delay in getting chemicals at Fallon the potassium- 
 iodid-starch method was used for a large part of the work. This 
 method, while primarily a quahtative one, was found to be fairly 
 reliable for quantitative determinations if a large quantity of reagent 
 was used when the nitrites were high, as indicated by a rapid develop- 
 ment of the blue-black color. The Grandval-Lajoux phenol-sulphonic 
 acid method as modified by Syme ^ was used for estimating -nitrates; 
 before determining nitrates the nitrites were removed by urea in acid 
 solution in accordance with Piccini's method. 
 
 Chlorids were frequently high in soil solutions in wliich nitrates were 
 to be determined, and it was necessary to remove them when present 
 in concentrations greater than 50 or 70 parts per million. This was 
 accomplished by the use of silver sulphate. 
 
 Chlorids ^ were determined by the Mohr method, titrating the 
 neutral solution with N/10 silver nitrate and using potassium chromate 
 as an indicator. Sulphates ^ were determined by the turbidity 
 method described by the Bureau of Soils.^ 
 
 DENITRIFICATION . 
 
 Studies of denitrification were made by inoculating Dunham's 
 peptone solution containing 0.2 per cent potassium nitrate with soil 
 and with a Frost scale measuring roughly the quantity of free nitrogen 
 evolved. Either ordinary fermentation tubes or test tubes inverted 
 in salt-mouth bottles were used. The latter method is preferred, as 
 it permits the use of larger quantities of soil for inoculations. 
 
 NITROGEN FIXATION. 
 
 Leguminous plants were examined for the presence of nodules, and 
 Azotobacter cultures were isolated from soil samples. 
 
 • Syme, W. A. The Oolorimetric Determination of Nitrates in Soil Solutions Con- 
 taining Organic Matter. Thirty-first Annual Report of the North Carolina Agricul- 
 tural Experiment Station, for the Year Ending June 30, 1908, pp. 64-65. 
 
 2 Both of these salts were determined by Mr. C. A. Jensen, of the Office of Western 
 Agricultural Extension of the Bureau of Plant Industry. 
 
 ^ Schreiner, Oswald, and Failyer, George H. Colorimetric, Turbidity, and Titration 
 Methods Used in Soil Investigations. Bulletin 31, Bureau of Soils, U. S. Dept of 
 Agriculture, 1906. 
 211 
 
12 
 
 SOILS OF THE TEUCKEE-CARSON IRRIGATION PROJECT. 
 
 NITRIFYING POWER OF SOILS AT DIFFERENT DEPTHS. 
 
 In investigations in soil bacteriology in the eastern United States 
 only the surface soil shows great variations. The soil of the arid 
 sections is much deeper, however; that is, the subsoil is less ''raw" 
 than in regions of heavier rainfall, a fact that has come to be more 
 or less famiUar to everyone studying soil conditions over extensive 
 areas. 
 
 Figure 2 shows the nitrification of samples from plats 100 and 110. 
 These plats, which are practically duplicates, are in a })roductive 
 
 Fig. 2. — Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
 from plats 100 and 110, Truckee-Carson Experiment Fann. Original nitrate present in samples from 
 plat 100: Depth, to 6 inches, 8 parts per million; to 12 inches, 15; 12 to 18 inches, 9; 18 to 24 inches, i.S; 
 24 to 36 inches, 6.5(i. From plat 110: Depth, to 6 inches, 9 parts per milhon; 6 to 12 inches, 7.4; 12 to 
 18 inches, 5.2; 18 to 24 inches, 4.8; 24 to 30 inches, 3.12. 
 
 alfalfa field which has been under cultivation for several years. The 
 soil is loose and sandy throughout the 3-foot depth. The nitrate 
 curves show that there is a gradual decrease in nitrifying power with 
 depth. 
 
 Figures 3 and 4 show the nitrification in samples from plats 120 and 
 130. These are in a fertile alfalfa field similar to the one mentioned 
 
 211 
 
NITRIFYTNd POWER OF SOILS AT DIFFERENT DEPTHS. 13 
 
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 Fig. 3.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
 from plat 120, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, to G 
 inches, 15.36 parts per million; 6 to 12 inches, 8.64; 12 to 18 inches, 6.72; 18 to 24 inches, 3.84; 24 to 36 inches, 
 2.88. 
 
 in the previous paragraph. The samples from plat 120 show nitrifica- 
 tion varying rather irregularly with depth. Samj:)les from plat 130 
 
 
 10 
 
 — 
 
 Si'ro&' €'7vlZ" I270I8" l8'7o24' 24ro36" 
 
 
 200 ^1 
 
 100 II 
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 Fig. 4.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
 from plat 130, Tnickee-rarson Experiment Farm. Original nitrate present in samples: Depth, to (> 
 inches, 13.3 parts per million; (i to 12 inches, 6.72; 12 to 18 inches, 9.6; 18 to 24 inches, 7.23; 24 to 36 inches, 
 14.4. 
 
14 
 
 SOILS OF THE TEUCKEE-CARSON IBEIGATION PROJECT. 
 
 practically failed to nitrify,^ although the two plats appear to be very 
 similar. 
 
 Figure 5 shows the relative nitrifying power of good and poor soils 
 collected from adjoining plats. Plat 160 has a loose sandy soil to a 
 
 Fig. 5. — Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
 from plats IdO and 170, Truekee-Carson Experiment Farm. Original nitrate present in samples from 
 plat KX): Depth, to (i inches, 8.04 parts per million; to 12 inches, 2.88;"12 to IS inches, 4.8; 18 to 24 inches, 
 G; 24 to 30 inches, 4.8. From plat 170: Depth, to inches, 4.32 parts per million; 6 to 12 inches, 0; 12 to 
 18 inches, 3.84; 18 to 24 inches, 3.0; 24 to 30 inches, 3. 
 
 depth of 18 inches; below this it is very heavy, but below 26 and 30 
 inches it is again lighter in texture. At the time of sampling, this 
 plat was supporting a fine growth of alfalfa. Plat 170 is in the north- 
 east corner of the same field, and was very similar except that the 
 
 ' This field had been irrigated a short time' before the samples were collected. 
 211 
 
KiTElFYlKG POWER OF SOILS AT DIFFERENT DEPTHS. 
 
 15 
 
 surface was a little more compact and the alfalfa was practically a 
 failure. The nitrification curves show the same general variations, but 
 the one of the poor soil is consistentl}^ below that of the productive soil. 
 
 Fig. 6.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
 from plat 180 (poor soil) and plat 190 (good soil), Truckee-Carson Experiment Farm. Original nitrate 
 present in samples from plat 180: Depth, to 6 inches, 2 parts per million; 6 to 12 inches, 3.5; 12 to 18 
 inches, 8.25; 18 to 24 Inches, 4.5; 24 to 36 inches, 25.75. From plat 190: Depth, to 6 inches, 4.5 parts per 
 mimon; 6 to 12 inches, 15.75; 12 to 18 inches, 11.25; 18 to 24 inches, 20.75; 24 to 36 inches, 21.75. 
 
 Plats 180 and 190 are located upon poor and good spots. The 
 texture of the samples is very similar, both being sandy, but the 
 surface of plat 180, the unproductive soil, is hard and compact as if 
 
 211 
 
16 
 
 SOILS OF THE TEUCKEE-CAESON TREIGATTON PROJECT. 
 
 held together by some cementing material. As shown in figure 6, the 
 nitrifying power of samples from plat 180 is almost nothing. In this 
 figure the chlorid and sulphate curves are of interest, as those of plat 
 180, the poor soil, are far above those of plat 190, the good soil.^ 
 
 Fig. 7.— Diagram showing tlie nitrification of ammonium sulphate in samples of soil from different depths 
 from plat 200, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, to G 
 inches, 7.68 parts per million; 6 to 12 inches, 5.8; 12 to 18 inches, 3.93; 18 to 24 inches, 4.32; 24 to 36 inches, 
 1.82. 
 
 Figures 7 to 10, inclusive, show the nitrifying power of samples of soil 
 from plats 200, 210, 220, and 230. They are in fields which have only 
 recently been leveled and irrigated; in fact, 1909 was the first year 
 they had been cropped. They produced a fair crop of barley, but the 
 
 .d'Tve' errlZ" I2'^I8" I8"7d24" 24to36" 
 
 200 k, 
 
 .00 i 
 
 ^j5c 
 
 «a* 
 
 " f*s 
 
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 -100 kJ 
 
 Q: 
 
 5 
 
 Fig. 8.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
 from plat 210, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, to (i 
 inches, 2.66 parts per million; 6 to 12 inches, 4.8; 12 to 18 inches, 4.16; 18 to 24 inches, 3; 24 to 36 inches, 2. 
 
 young alfalfa sown in the barley was doing only fairly well. The 
 curves from all of these plats show a very low nitrifying power, yet a 
 glance at the figures shows that nitrates were present in moderate 
 quantities in the original samples. 
 
 Bridge readings on these samples were made by Mr. Jensen. 
 
 211 
 
NITKIFYING POWEE OF SOILS AT DIFFERENT DEPTHS. 
 
 17 
 
 Figures 11 and 12 present the results obtained from samples of soil 
 from plats 240, 250, 260, and 270. The fields in which these plats are 
 
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 Fig. 9.— Diagram showing tlie nitrification of ammonium sulphate in samples of soil from different deptiis 
 from plat 220, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, to 6 
 inches, 7.68 parts per million; H to 12 inches, (i. 91; 12 to 18 inches, 10; 18 to 24 inches, 5. (i4; 24 to 36 inches, 6. 
 
 located have been merely leveled and left fallow, receiving regular 
 applications of irrigation water. The field containing plats 240 and 
 250 is never cultivated, while that containing plats 260 and 270 is 
 
 Fig. 10. — Diagram showing the nitrification of anunonium sulphate in samples of soil from different depths 
 from plat 230, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, to li 
 inches, 10 parts per million; 6 to 12 inches, 8. IG; 12 to 18 inches, S; 18 to24inches,4.5(i; 24 to 36 inches, 9. li. 
 
 cultivated according to thorough summer-fallow metliods. As the 
 conditions are abnormal it is not surprising that the curves of chlorids 
 78011°— Bui. 211—11 3 
 
18 
 
 SOILS OF THE TRUCKEE-CARSON IRRIGATION PROJECT. 
 
 and sulphates, as well as the curve showing nitrification, should be so 
 erratic and variable. 
 
 Figure 13 shows the nitrifying power of samples from plats 280 and 
 
 Fig. U.— Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
 from plats 240 and 250, Truckee-Carson Experiment Farm. Original nitrate present in samples from 
 plat 240: Depth, to 6 inches, 6.8 parts per million; 6 to 12 inches, 8; 12 to 18 inches, 10.4; 18 to 24 inches, 
 C; 24 to 36 inches, 5. From plat 250: Depth, to 6 inches, 28 parts per million; 6 to 12 inches, 48; 12 to 
 18 inches, 6; IS to 24 inches, 5.2; 24 to 36 inches, 7. 
 
 290, located in an old alfalfa field just north of Fallon. These soils 
 are ver}^ productive, and it was expected that they would show 
 a greater nitrifying power than thev did. This mav possibly be 
 
 211 
 
NITRIFICATION OF SAMPLES IN SOLUTION. 
 
 19 
 
 explained, however, by the original high nitrate content of the soil, 
 as there is often a tendency for the nitrifying power of a soil to 
 decrease as nitrates accumulate. 
 
 NITRIFICATION OF SAMPLES IN SOLUTION. 
 
 In order to further test for the presence of nitrif:vang bacteria and 
 also to study some of their characteristics, inoculations were made 
 
 Fig. 12.— Diagram showing the nitriflcation of ammonium sulphate in samples of soil from different depths 
 from plats 2G0 and 270, Truckee-Carson Experiment Farm. Original nitrate present in samples from 
 plat 2G0: Depth, to 6 inches, 02 parts per million; to 12 inches, 30; 12 to 18 mches, 18.75; 18 to 24 
 inches, 35.7; 24 to 3G inches, 30. From plat 270: Depth, to inches, 100 parts per milUon; 6 to 12 
 mches, 27.7; 12 to 18 inches, 50; 18 to 24 inches, 40; 24 to St; inches, 50. 
 
 into media consisting entirely of inorganic material wliich is not suit- 
 able for the growth of saprophytic bacteria. ^ Curves have not been 
 plotted from the data thus obtained, as the conditions were too 
 abnormal to warrant considering the differences from a quantitative 
 
 » Winogradsky and Omelianski's Fluid Culture-Medium for Isolating the Nitrate 
 Bacteria from Soils, and Winogradsky and Omelianski's Fluid Culture-Medium for 
 Isolating the Nitrite Bacteria from Soils. Centrallilatt fiir Bakteriologie, Parasiten- 
 kunde und Infektionskrankheiten, vol. 5, pt. 2, 1899, pp. 537-549. 
 211 
 
20 
 
 SOILS OF THE TEUCKEE-CAESON lEEIGATION PEOJECT. 
 
 standpoint. The results are all expressed in Table I as parts of 
 nitrogen per million of the solution. 
 
 Fig. 1.3. — Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
 Irom plats 280 and 290, Truckee-Carson Experiment Farm. Original nitrate present in samples from 
 plat 280: Depth, to (i inches, 12 parts per million; 6 to 12 inches, 10; 12 to IS inches, 6; 18 to 24 inches, 
 15; 24 to 36 inches, 02.5. From plat 290: Depth, to 6 inches, GO parts per million; li to 12 inches, (iO; 
 12 to 18 inches, 55.4; 18 to 24 inches, 60; 24 to 36 inches, 00. 
 
 Table I. — Nitrification in solution of samples of soil from plats 100. 110. 180, 190, 220, 
 260, 270, and 280,^ Truckee-Carson Experiment Farm. Incuhated^al 28° C. 
 
 
 
 Ammonia to nitrite 
 
 Nitrite to nitrate 
 
 
 Depth 
 of soil. 
 
 (parts per million V^ 
 
 (parts per million) » 
 
 plat. 
 
 
 
 
 
 ) 
 
 
 
 6 days. 
 
 12 days. 
 
 10 days. 20 days. 
 
 
 Inches. 
 
 1 . 
 
 
 
 100 
 
 0-6 
 
 (i. 50 
 
 25 
 
 91.60 
 
 9t;. 00 
 
 
 6-12 
 
 5.00 
 
 25 
 
 64.80 
 
 60.00 
 
 
 12-18 
 
 6.50 
 
 18 
 
 86.40 
 
 81.60 
 
 110 
 
 0-6 
 
 .50 
 
 15 
 
 1 
 
 180 
 
 (J-12 
 12-18 
 0-6 
 
 3.25 
 8.00 
 0.00 
 
 20 
 25 
 
 15 
 
 ... 1 
 
 
 
 24 00 
 
 86.40 
 
 
 ()-12 
 
 0.00 1 15 
 
 3.60 
 
 2.40 
 
 
 12-18 
 
 0.00 : 00 
 
 2.40 
 
 3.00 
 
 190 
 
 0-6 
 
 1.00 16 
 
 72.00 
 
 74.00 
 
 220 
 
 0-6 
 
 0.00 00 
 
 13.20 
 
 SO. 00 
 
 
 6-12 
 
 0.00 00 
 
 3.60 
 
 5.32 
 
 
 12-18 
 
 0.00 00 
 
 2.40 
 
 5.60 
 
 260 
 
 0-6 
 
 .5.00 17 
 
 76.80 
 
 74.00 
 
 
 (1-12 
 
 3. 00 ' 10 
 
 57.60 
 
 54.40 
 
 
 12-18 
 
 3. 00 1 10 
 
 2.88 
 
 17.55 
 
 270 
 
 0-6 
 
 6. 50 20 
 
 9.60 
 
 43.20 
 
 
 6-12 
 
 0.00 00 
 
 8.64 
 
 ■ 60.00 
 
 2801 
 
 0-6 
 
 5. 75 , 20 
 
 21.60 
 
 81. 60 
 
 
 6-12 
 
 1.00 20 
 
 40.80 
 
 81.60 
 
 
 12-18 
 
 1.00 20 
 
 38.40 
 
 81.60 
 
 1 Plat 280 is located in an old alfalfa field one-fourth mile north of Fallon. 
 
 2 Used medium for isolating nitrite bacteria. ^ Used medium for isolating nitrate bacteria. 
 
 211 
 
CHLORIDS AND SULPHATES. 
 
 21 
 
 It will be seen that the nitrifiers and especially the nitrate bacteria 
 develop quite well in solutions. It should be noted that the only 
 samples that failed to produce nitrites were those taken at 6-inch, 
 12-inch, and 18-inch depths from plat 220, which failed to nitrify in 
 soil. (See fig. 9.) This soil, however, produced nitrates quite readily. 
 This suggests tlie possibility that the lack of nitrification in this soil 
 may be due to lack of nitrite bacteria. 
 
 CHLORIDS AND SULPHATES. 
 
 In alkali studies it is recognized that as a rule the chlorid type is more 
 injurious to ordinary farm crops than the sulphate type. Further, in 
 some investigations in the soils of the arid regions it has been found 
 
 «j875 
 
 1 
 
 ^75.0 
 m37.5 
 
 1 
 
 ^25.0 
 $12.5 
 
 ISO 190 170 150 100 160 110 120 
 
 1225 V) 
 1050 IJi 
 875 ^ 
 
 1 
 
 700 J 
 525 1 
 
 Nl 
 
 1 
 
 350 ft 
 
 175 ^ 
 
 
 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 jjitrgjs^ 
 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 ~^'^^^^. 
 
 \ 
 
 
 
 
 
 c 
 
 "Z^^ 
 
 '^jjorids:- 
 
 ' 
 
 \ 
 
 ^> 
 
 
 
 Fig. 14.— Diagram showing the relation between the quantity of all^:ali and the nitrification in samples of 
 soil from plats 180, 190, 170, 150, 100, HiO, 110, and 120, Tnickee-Carson Experiment Fami. Samples 
 taken from depths of to inches. 
 
 that high nitrates correlate with the sulphate type, while low nitrates 
 are usually associated with the chlorid type. It was thought, tliere- 
 fore, that it would be of interest in connection with this work to study 
 the relation of chlorids and sulphates to the nitrifying power. 
 
 In plotting these curves the different plats are arranged in such 
 an order that the nitrification of ammonium sulphate by the dif- 
 ferent samples, which is the index of the difference of their powers 
 of nitrification, forms an ascending series. Four diagrams are pre- 
 sented (figs. 14 to 17), one for each depth from which samples of soil 
 were taken. Figure 14, representing the surface samples, shows no 
 relation between the concentration of soluble salts and nitrifying 
 power. Figures 16 and 17, representing the deeper samples, are 
 
 211 
 
22 
 
 SOILS OF THE TEUCKEE-CARSON IRRIGATION PROJECT. 
 
 not in close agreement, although high alkali consisting of both 
 chlorids and sulphates is apparently correlated mth low nitrification. 
 Little if any difference is to be noted between the effect of the chlorid 
 and the sulphate types of alkali. 
 
 DENITRIFICATION. 
 
 In order to test for the presence of denitrifying bacteria several 
 inoculations were made into Dunham's solution containing 0.2 per 
 
 875 
 75.0 
 $62.5 
 ^50.0 
 |37.s 
 ^250 
 
 1 ° 
 
 180 120 170 100 190 150 160 110 
 
 1 
 
 1050$ 
 
 875"^ 
 
 700 § 
 
 
 525^ 
 350 1 
 
 -0 
 
 
 1 
 \ 
 I 
 
 
 
 
 
 
 
 
 
 \\ 
 U 
 U 
 
 V 
 
 
 
 
 
 
 
 
 
 Vl 
 U 
 
 V 
 
 \\ 
 \> 
 \\ 
 
 
 
 
 
 
 
 
 
 V 
 
 
 
 
 ^ 
 
 
 y^ 
 
 
 
 \ 
 
 / 
 
 ■v . 
 
 \ 
 
 \ 
 
 02i>^ 
 
 
 
 
 
 / 
 
 
 
 / 
 / 
 
 / 
 / 
 / 
 / 
 
 
 N 
 
 
 
 
 
 
 
 / 
 
 c/" 
 
 \\.^ 
 
 SUjg'l''JSi 
 
 
 '■V 
 
 
 
 
 
 
 
 
 
 
 
 
 Fig. 15.— Diagram showing the relation between the quantity of alkali and the nitrification in samples of 
 soil from plats 180, 1'20, 170, 100, 190, 150, IfiO, and 110, Truckee-Carson Experiment Farm. Samples 
 taken from depths of tl to 12 inches. 
 
 cent of potassium nitrate, and the free nitrogen gas evolved was 
 measured. This medium favors the growth of tliis class of bacteria. 
 The conditions thus produced are abnormal and the quantitative 
 differences shown in Table II should not be taken too seriously. It 
 will be seen from the table that denitrifying bacteria are present and 
 active in almost all of the soils tested. 
 
 211 
 
DENITRIFICATION. 
 
 23 
 
 Pig. 16.— Diagram showing the relation between the quantity of alkali and the nitrification in samples of 
 soil from plats ISO, 190, 170, 100, 120, 160, 110, and 150, Truckee-Carson Experiment Farm. Samples 
 taken from depths of 12 to 18 inches. 
 
 lOOo 
 
 ^ 75.0 
 ^62.5 
 
 1 
 
 ^ 50.0 
 |375 
 (V 25.0 
 
 g,2.s 
 
 1 
 
 
 
 180 (70 190 100 110 160 150 120 
 
 1400 
 1225 1 
 1050^ 
 875 Q 
 700 ^ 
 
 525 1 
 
 1 
 3S0| 
 
 175 ^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 \ 
 
 \ 
 \ 
 
 \ 
 
 
 
 
 
 
 
 
 
 \ 
 \ 
 \ 
 
 \ 
 
 
 
 
 
 
 
 
 
 \ 
 
 \ 
 
 \ 
 \ 
 \ 
 
 
 
 
 
 
 
 
 
 \ 
 \ 
 
 1 
 
 
 
 
 
 
 
 
 
 \ 
 
 
 
 
 ^ 
 
 
 
 V 
 T 
 
 
 \ 
 
 \ 
 \ 
 \ 
 \ 
 
 
 
 / 
 
 
 
 
 
 
 \ 
 
 /V/frates 
 
 -^ 
 
 
 
 
 
 
 
 
 
 ^^ 
 
 <Lfe*^ 
 
 "^•» 
 
 ::^ 
 
 
 
 ^^^ 
 
 
 /^ 
 
 
 
 
 
 
 
 Fig. 17.— Diagram showing the relation between the quantity of alkali and the nitrification in samples of 
 soil from plats 180, 170, 190, 100, 110, 160, 150, and 120, Truckee-Carson Experiment Farm. Samples 
 taken from depths of 18 to 24 inches. 
 211 
 
24 
 
 SOILS OP THE TRUCKEE-CARSON IRRIGATION PROJECT. 
 
 Table II.- 
 
 Denitriji cation in solution of samples of sml from plats 180. 190. 2S0, 260, 
 270. 280,^ and 290,^ Truckcc- Carson Experiment Farvi. 
 
 No. of 
 
 Depth of 
 
 Gas formed 
 
 Gas formed 
 
 plat. 
 
 soil. 
 
 in 7 days. 
 
 in 15 days. 
 
 
 Inches. 
 
 Per cent. 
 
 Per cevt. 
 
 180 
 
 0-6 
 
 25 
 
 25 
 
 
 6-12 
 
 20 
 
 30 
 
 
 12-18 
 
 20 
 
 25 
 
 190 
 
 0-6 
 
 22 
 
 32 
 
 
 6-12 
 
 30 
 
 40 
 
 
 12-18 
 
 32 
 
 42 
 
 2.30 
 
 0-6 
 
 20 
 
 30 
 
 
 6-12 
 
 21 
 
 30 
 
 
 12-18 
 
 20 
 
 35 
 
 260 
 
 0-6 
 
 40 
 
 53 
 
 
 6-12 
 
 15 
 
 23 
 
 
 12-18 
 
 20 
 
 30 
 
 270 
 
 0-6 
 
 20 
 
 30 
 
 
 6-12 
 
 20 
 
 30 
 
 
 12-18 
 
 20 
 
 30 
 
 280' 
 
 0-6 
 
 00 
 
 00 
 
 
 6-12 
 
 Trace. 
 
 Trace. 
 
 
 12-18 
 
 Trace. 
 
 Trace. 
 
 2901 
 
 0-6 
 
 22 
 
 40 
 
 
 6-12 
 
 10 
 
 18 
 
 
 12-18 
 
 45 
 
 62 
 
 ' Plats 280 and 290 are located in an old alfalfa field one-fourth mile north of Fallon. 
 RELATIVE NUMBERS OF BACTERIA IN DIFFERENT SOILS. 
 
 An estimation of the number of bacteria in a gram of soil that 
 would develop aerobically upon beef agar was made for many of the 
 sampling plats in accordance with the method previously described, 
 the results of which are shown in Table III. In accord with the 
 reports of other investigators, ^ the data presented in Table III 
 clearly show that the numbers of bacteria found in the different 
 samples bear no consistent relation to the fertility or crop-producing 
 power of the respective fields. 
 
 No attempt was made to determine the relative numbers of proto- 
 zoa in samples of soil from the good and })oor areas. If the develop- 
 ment of protozoa is determined by their food supply,' in other words, 
 by the numbers of bacteria existing in the soil, it is obvious that in this 
 region the crop-producing power can not be limited ^ by the abundance 
 of protozoa. 
 
 ' Lohnis, F. Ein Beitrag zAir Methodik der bakteriologischen Bodenuntersuchung. 
 Centralblatt fiir Bakteriologie, Parasitenkunde und Infektionskrankheiten. pt. 2, 
 vol. 12, no. 6-8, June 24, 1904, pp. 262-267. 
 
 Chester, Frederick D. The Bacteriological Analysis of Soils. Bulletin 65, Dela- 
 ware College Agricultural Experiment Station, March 1, 1904. 
 
 Voorhees, Edward B., and Lipman, Jacob G. A Review of Investigations in Soil 
 Bacteriology. Bulletin 194, Office of Experiment Stations, U. S. Dept. of Agriculture, 
 October 26, 1907. 
 
 - Russell, E. J., and Hutchinson, H. B. The Effect of Partial Sterilization of Soil 
 on the Production of Plant Food. Contributions from the Laboratory of the Rotham- 
 sted Experimental Station, October, 1909, pp. 111-144. 
 
 ■' Hall, A. D. The Fertility of the Soil. Science, n. s., vol. 32, no. 820, September 
 16, 1910, pp. 363-371. 
 211 
 
DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AREAS. 
 
 25 
 
 Table III. — Number of bacteria 'per gram of soil and nitrifying power of samples from 
 plats 10, 20. 30, 40, 180, 190, 290,^ 240, 260, and 270, Trucl-ee-Carson Experiment 
 Farm. 
 
 
 
 
 Nitrifying 
 
 
 No. of 
 plat. 
 
 Depth of 
 soil. 
 
 Number of 
 bacteria per 
 
 power of 
 soils (parts 
 
 Character of soil. 
 
 
 gram. 
 
 per mil- 
 
 
 
 
 
 lion). 
 
 
 
 Inchex. 
 
 
 
 
 :o 
 
 0-6 
 
 435,000 
 
 4.4 
 
 Very poor. 
 
 
 6-12 
 
 251,000 
 
 2.0 
 
 
 
 12-18 
 
 26, 650 
 
 .0 
 
 
 
 18-24 
 
 146,250 
 
 3.0 
 
 
 
 24-36 
 
 1,000 
 
 .0 
 
 
 20 
 
 0-6 
 
 19,500 
 
 54.2 
 
 Very productive. 
 
 
 6-12 
 
 11,250 
 
 6.8 
 
 Good growth of 
 
 
 12-18 
 
 30,000 
 
 1.0 
 
 alfalfa. 
 
 
 18-24 
 
 4,500 
 
 .0 
 
 
 
 24-36 
 
 3,000 
 
 .0 
 
 
 30 
 
 0-6 
 
 160,000 
 
 3.0 
 
 Poor and com- 
 
 
 6-12 
 
 65,000 
 
 .0 
 
 pact. 
 
 
 12-18 
 
 262,000 
 
 .0 
 
 
 
 18-24 
 
 19, 855 
 
 .0 
 
 
 
 24-36 
 
 10,000 
 
 .0 
 
 
 40 
 
 0-6 
 
 210,000 
 
 20.4 
 
 Productive. 
 
 
 6-12 
 
 20,000 
 
 4.0 
 
 Good growtli of 
 
 
 12-18 
 
 135, 000 
 
 1.0 
 
 alfalfa. 
 
 
 18-24 
 
 45, 000 
 
 .0 
 
 
 
 24-36 
 
 1,000 
 
 .0 
 
 
 180 
 
 0-6 
 
 60,000 
 
 4.72 
 
 Very poor. 
 
 
 6-12 
 
 175, 000 
 
 1.54 
 
 Alkali higli. 
 
 
 12-18 
 
 180,000 
 
 4.32 
 
 (See fig. 6.) 
 
 
 18-24 
 
 4,000 
 
 2.54 
 
 
 190 
 
 0-6 
 
 3,600 
 
 36.30 
 
 Productive. 
 
 
 6-12 
 
 168,000 
 
 37.45 
 
 
 
 12-18 
 
 1,554,000 
 
 12. 75 
 
 
 
 18-24 
 
 704,000 
 
 12.25 
 
 
 290' 
 
 0-6 
 
 273,000 
 
 30.00 
 
 Productive. 
 
 
 6-12 
 
 396,000 
 
 20. 00 
 
 Old alfalfa fielfl. 
 
 
 12-18 
 
 262, 500 
 
 14.60 
 
 (Seeflg. 13.J 
 
 
 18-24 
 
 327, 000 
 
 4.00 
 
 
 240 
 
 0-6 
 
 52, 000 
 
 69.00 
 
 Fallow. (See 
 
 
 6-12 
 
 78, 700 
 
 4.50 
 
 fig. 11.) 
 
 
 12-18 
 
 56,000 
 
 .40 
 
 
 260 
 
 0-6 
 
 81,000 
 
 18.00 
 
 F a 1 1 w. (See 
 
 
 6-12 
 
 153,300 
 
 40.00 
 
 fig. 12.) 
 
 270 
 
 0-6 
 
 72,000 
 
 100.00 
 
 
 
 6-12 
 
 2,790,000 
 
 92. 30 
 
 
 ' Plat 290 is located in an old alfalfa field one-fourth mile north of Fallon. 
 
 DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AREAS. 
 
 Plats 300 to 350 are representative of a somewhat extensive type 
 of soil of the Truckee-Carson project. This soil is very unproductive 
 as a rule, almost barren in many cases, yet all through it, wherever 
 properly leveled and irrigated, are spots of a few square rods in area 
 that are normal and productive. The difference between these two 
 conditions seemingly can not be explained by any of the now known 
 causes of infertility. There is a certain difference in texture, or rather 
 in the physical properties; the productive soil is loose and sandy, 
 while the unproductive type, although sandy, contains a small quan- 
 tity of clay which when shaken up with water remains suspended 
 indefinitely and the soil cements on drying. These physical differ- 
 ences, while no doubt factors, do not seem adequate causes of the 
 extremely low fertility. The total alkah content is not high enough 
 
 211 
 
26 SOILS OF THE TEUCKEE-CAKSON IRRIGATION PROJECT. 
 
 to produce toxic effects, and a lack of mineral plant food in the virgin 
 soils is almost out of the question. 
 
 Both soils are' low in organic matter, as are all arid soils. Good 
 soil management in other somewhat similar regions would indicate 
 that the addition of organic matter to these soils in the form of barn- 
 yard manure or green manure should produce beneficial physico- 
 chemical effects, and such treatments have been applied somewhat 
 extensively as a matter of experiment during the last two or three 
 years. The poor soil apparently has not been benefited to a noticea- 
 ble degree. The good soil has been somewhat improved, although 
 even here the improvement has not been striking. A minute field 
 examination of these good and poor spots a year or more after they 
 had received applications of organic matter revealed a remarkable 
 difference; all traces of the organic material had disappeared from 
 the fertile spots, while the larger part of the manure added to the 
 infertile spots was in an almost perfect state of preservation. Another 
 peculiar difference was that in the poor spots, at depths of 6 to 28 
 inches, an irregularly distributed, dark-colored, foul-smelling layer 
 was found, undoubtedly due to the presence of a peculiar organic 
 decomposition product, while such a layer was never found associated 
 with good soil. It should not be inferred from this description that 
 this black layer was found only where organic matter has been added 
 as a treatment; it was quite generally distributed through these 
 infertile soils and is presumably due to the decay of such material as 
 was turned into the soil when it was first reclaimed, such as sagebrush, 
 greasewood, rabbit brush, and other desert plants, together with the 
 roots of these plants which have been accumulating for long periods 
 of time. Laboratory samples showed that this black substance was 
 easily oxidized, for when a sample was taken to the laboratory, dried, 
 and subsequently moistened for physiological experiments, all traces 
 of the black color and peculiar odor disappeared. 
 
 These unusual conditions of the decay of organic matter are neces- 
 saril}^ somewhat closely associated with improper bacteriological 
 conditions; that is, the improper utilization of organic fertilizers is 
 due either to an improperly balanced or incomplete bacterial flora 
 or to physical or chemical conditions preventing the performance of 
 the normal activities of the bacteria present. 
 
 Titrations of some of the aqueous extracts indicated that sodium 
 carbonate (black alkali) was present in the poor soils but not in the 
 good soils. It was also apparent that calcium sulphate and gypsum, 
 when applied in large quantities, produced a decided effect in floc- 
 culating the finely divided or colloidal clays. Samples were collected 
 with a sterile spatula from the sides of freshly dug holes and placed 
 in sterile containers. Portions of these samples were inoculated into 
 'Ml 
 
DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AEEAS. 
 
 27 
 
 Winogradsky's solutions and also into flasks of sterile water, from 
 which counts were made. The remaining portions of the samples 
 were then emptied on clean sheets of paper in the culture room and 
 left to dry under conditions as free as possible from chance contami- 
 nations. Fifty-gram portions from each sample were removed for 
 original nitrate determinations, and another equal portion was re- 
 placed in the original containers, brought up to optimum moisture 
 content with 5 cubic centimeters of 0.4 per cent sulphate of ammonia 
 and distilled water, incubated for two weeks at 28° C, and the nitri- 
 fication determined. A duplicate series to which was added a 2 per 
 cent solution of calcium sulphate was prepared. At the beginning 
 of the incubation period the total weight of the container and soil 
 at optimum moisture was taken, and the loss from evaporation was 
 restored with sterile distilled water at 3-day intervals during the 
 incubation period. The results of the experiment appear in Tables 
 IV and V. 
 
 Table 1\ .^Effect of calcium sulphate upon nitrification in samples of soil from plats 
 300 and SIO, Truckee- Carson Experiment Farm, representing poor soil conditions. 
 Incubated 15 days at 28° C. 
 
 NO CALCIUM SULPHATE ADDED TO SAMPLES. 
 
 No. of 
 plat. 
 
 300 
 310 
 
 Depth of 
 soil. 
 
 Nitrogen as nitrite (parts per 
 million). 
 
 Nitrogen as nitrate (parts per 
 million). 
 
 Original. 
 
 Final. 
 
 Gain. 
 
 Original. 
 
 Final. 
 
 Gain. 
 
 Inches. 
 0-6 
 6-12 
 12-18 
 18-24 
 0-6 
 6-12 
 12-18 
 18-24 
 
 1.2 
 2.0 
 1.2 
 .0 
 1.0 
 1.0 
 1.0 
 1.0 
 
 5.60 
 3.12 
 1.68 
 1.20 
 7.28 
 2.10 
 .80 
 1.20 
 
 4.40 
 1.12 
 
 .48 
 
 1.20 
 
 6.28 
 
 1.10 
 
 - .20 
 
 .20 
 
 9.12 
 7.68 
 6.14 
 4.56 
 4.80 
 1.60 
 4.32 
 3.07 
 
 56.40 
 00.00 
 00.00 
 00.00 
 96.00 
 00.00 
 00.00 
 00.00 
 
 46.28 
 
 - 7.68 
 
 - 6.14 
 
 - 4.56 
 91.20 
 
 - 1.60 
 
 - 4.32 
 
 - 3.07 
 
 WITH 2 PER CENT CALCIUM SULPHATE ADDED TO ALL SAMPLES. 
 
 300 
 
 0-6 
 
 1.2 
 
 2.80 
 
 1.60 
 
 9.12 
 
 57.00 
 
 47.88 
 
 
 6-12 
 
 2.0 
 
 2.80 
 
 .80 
 
 7.68 
 
 00.00 
 
 - 7.68 
 
 
 12-18 
 
 1.2 
 
 2.70 
 
 1.50 
 
 6.14 
 
 00.00 
 
 - 6.14 
 
 
 18-24 
 
 .0 
 
 .88 
 
 .88 
 
 4.56 
 
 00.00 
 
 - 4.56 
 
 310 
 
 0-6 
 
 1.0 
 
 4.00 
 
 3.00 
 
 4.80 
 
 96.00 
 
 91.20 
 
 
 6-12 
 
 1.0 
 
 2.40 
 
 1.40 
 
 1.60 
 
 1.20 
 
 - .40 
 
 
 12-18 
 
 1.0 
 
 1.68 
 
 .68 
 
 4.32 
 
 0.00 
 
 4.32 
 
 
 18-24 
 
 1.0 
 
 1.56 
 
 .56 
 
 3.07 
 
 0.00 
 
 - 3.07 
 
 211 
 
28 
 
 SOILS OF THE TRUCKEE-CAKSON lERIGATION PROJECT. 
 
 Table V. — Effect of calcium sulphate upon nitrification in samples of soil from pint 
 320, Truckee-Carson Experiment Farm, representing good soil conditions. Incubated 
 15 days at 28° C. 
 
 NO CALCIUM SULPHATE ADDED TO SAMPLES. 
 
 No. of 
 plat. 
 
 Depth of 
 soil. 
 
 Nitrogen as nitrite (parts per 
 million). 
 
 Nitrogen as nitrate (parts per 
 million). 
 
 Original. 
 
 final. 
 
 Gain. 
 
 Original. 
 
 Final. 
 
 Gain. 
 
 320 
 
 Inches. 
 0-6 
 6-12 
 12-18 
 18-24 
 
 1.4 
 
 1.5 
 
 .0 
 
 .8 
 
 4.00 
 1.20 
 1.00 
 1.40 
 
 2.60 
 
 - .30 
 
 1.60 
 
 .60 
 
 3.84 
 18.24 
 15.90 
 15.30 
 
 80.64 
 
 70. 80 
 
 5.00 
 
 0.00 
 
 76.80 
 
 58.56 
 
 -10.90 
 
 -15.30 
 
 WITH 2 PER CENT CALCIUM SULPHATE ADDED TO ALL SAMPLES. 
 
 320 
 
 0-6 
 
 L4 
 
 5.00 
 
 3.60 
 
 3.84 
 
 8L60 
 
 77.76 
 
 
 6-12 
 
 1.5 
 
 1.68 
 
 .13 
 
 18.24 
 
 76.80 
 
 58.56 
 
 
 12-18 
 
 .0 
 
 1.82 
 
 1.82 
 
 15.90 
 
 4.56 
 
 -11.36 
 
 
 18-24 
 
 .8 
 
 .60 
 
 - .20 
 
 15.30 
 
 .00 
 
 -15.30 
 
 The gain in nitrates, or the nitrifying power of these samples of 
 soil, is shown in figure 18. 
 
 These experiments on nitrification indicate that the difference in 
 productiveness is not clue to a suspension of nitrification, and also 
 that it is not due to the presence of sodium carbonate, as the addition 
 of calcium sulphate to the samples had absoluteh' no effect: the 
 treated and untreated samples could really be considered duphcates. 
 It would seem also that the infertility or the lack of decay of organic 
 substances is not due to lack of air. It might be argued that lab- 
 oratory conditions were not such as would favor the compacting or 
 cementing of the sam])les, yet it must be remembered that the corn- 
 field containing plats 300, 310, and 320 was kept well cultivated and 
 no crust was allowed to form during the growing season. Tables 
 VI and VII show the nitrification of the different samples in Wino- 
 gradsky and Omelianski's media. 
 
 Table VI. — Nitrite formed from ammonia by samples of soil from plats 330, 340, and 
 350, Truckee-Carson Experiment Farm, in medium for nitrite bacteria. Incubated 
 at 28° C. 
 
 
 
 Nitrite 
 
 Nitrite 
 
 
 
 Depth of 
 of soil. 
 
 formed in 
 
 formed in 
 
 Charac- 
 
 No. of 
 plat. 
 
 5 days 
 (parts'per 
 
 10 days 
 (parts per 
 
 ter of 
 soil. 
 
 
 
 million). 
 
 million). 
 
 
 
 Inches. 
 
 
 
 
 330 
 
 0-6 
 
 0.0 
 
 4.8 
 
 Poor. 
 
 
 6-12 
 
 .0 
 
 .0 
 
 
 
 12-18 
 
 .0 
 
 .0 
 
 
 
 18-24 
 
 .0 
 
 .0 
 
 
 340 
 
 0-6 
 
 9.6 
 
 10.4 
 
 Do. 
 
 
 6-12 
 
 12.8 
 
 12.8 
 
 
 
 12-18 
 
 12.8 
 
 12.8 
 
 
 
 18-24 
 
 .0 
 
 12.2 
 
 
 350 
 
 0-6 
 
 .0 
 
 Trace. 
 
 Good. 
 
 
 0-12 
 
 .0 
 
 4.8 
 
 
 
 12-18 
 
 .0 
 
 .0 
 
 
 
 18-24 
 
 .0 
 
 .0 
 
 
 211 
 
DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AREAS. 
 
 29 
 
 Fig. 18.— Diagram showing the effect of ealcimn sulphate upon nitrification of ammonium sulphate in 
 samples of soil from plat 300, Truckee-Carson Experiment Farm, representing poor soil "A "; plat 310, 
 representing poor soil " B"; and plat 320, representing good soil. 
 
 Table VII. — Nitrate formed from nitrite by samples of soil from plats 330 and 350, 
 Truckee-Carson Irrigation Project, in medium for nitrate bacteria. Incubated at 28° C. 
 
 211 
 
 
 
 Nitrate 
 
 Nitrate 
 
 
 
 
 formed in 
 
 formed in 
 
 Charac- 
 
 No. of 
 plat. 
 
 soil. 
 
 10 days 
 
 20 days 
 
 ter of 
 
 (parts per 
 
 (parts per 
 
 soil. 
 
 
 
 million). 
 
 million). 
 
 
 
 Inches. 
 
 
 
 
 330 
 
 0-6 
 
 24.00 
 
 90.32 
 
 Poor. 
 
 
 6-12 
 
 19.68 
 
 90.32 
 
 
 
 12-18 
 
 12.60 
 
 81.28 
 
 
 
 18-24 
 
 19. 80 
 
 90.32 
 
 
 ?,m 
 
 0-6 
 
 12.50 
 
 54.19 
 
 Oood. 
 
 
 (i-12 
 
 24.00 
 
 72. 25 
 
 
 
 12 18 
 
 
 
 
 
 18-24 
 
 4.12 
 
 90. 32 
 
 
30 
 
 SOILS OF THE TRUCKEE-CAESON TRRIGATTON PROJECT. 
 
 The fact that nitrification was feeble in the good soil and also in 
 one of the poor soils should not be overemphasized, for soils that will 
 nitrify under normal conditions frequently fail to do so in solutions. 
 On the other hand, the rapidity with which the nitrate bacteria 
 worked in solutions, even when they failed to do so in the soil, is 
 interesting and almost without parallel. It is not surprising that a 
 soil should fail to nitrify in solution, but it is remarkable that samples 
 which failed to nitrify when kept warm and moist — ideal conditions 
 for nitrification — should produce nitrates rapidly when inoculated 
 into solutions. 
 
 The production of ammonia from organic material by soil bacteria 
 furnishes a means of measuring the power of the soil flora to break 
 down nitrogenous organic substances. Thus it would seem that the 
 soils of the plats in which organic matter remained indefinitely in a 
 
 ^1200 
 
 ^iiioo 
 
 ^2 1000 
 IP^ 900J 
 
 II 
 
 DEPTH /1TWH/CH S/IMP/.ES MVEPE T/JHE/V- 
 
 
 Fig. 19. — Diagram showing the ammoDification of peptone in 7 days in samples of soil from plat 350 (good 
 soil) and from plats 330 and 340 (poor soil), Truckee-Carson Experiment Farm. 
 
 state of preservation must have a very low ammonifying power. 
 The medium described previously, consisting of 1.5 per cent peptone 
 and inorganic salts, was inoculated with samples from plats 330, 
 340, and 350, and the ammonia produced determined at 10-day and 
 20-day incubation periods by distillation with magnesia.^ The 
 results of this experiment are shown in figures 19 and 20. 
 
 As the ammonification of the samples of poor soil, plats 330 and 
 340, was very similar, the results are averaged and shown as a single 
 curve. 
 
 The fact that there is no increase between the 7-day and 15-day 
 periods indicates that the maximum had been reached before any 
 
 1 Dr. J. G. Lipman has recently suggested the use of dried blood as a source of 
 nitrogen for work of this character. See Lipman, Jacob G., and Brown, Percy E., 
 "Experiments on Ammonia and Nitrate Formation in Soils," in Centralblatt flir 
 Bakteriologie, Parasitenkunde und Infektionskrankheiten, pt. 2, vol. 26, no. 20-24, 
 April 9,1910, pp. 590-(i32. 
 211 
 
DETAILED STUDY OF SOIL TYPICAL OF EXTENSIVE AREAS. 
 
 31 
 
 determinations were made. Yet these results show conclusively that 
 in both good and poor soils there are large numbers of ammonifiers 
 which are physiologically active if proper conditions are provided for 
 them to develop. The relative differences in their ammonifying 
 power and whether or not there are conditions in the soil to prevent 
 their normal activities remain to be shown by further experiment. 
 
 Denitrification is of two kinds: The reduction of nitrates to lower 
 forms or transformation into organic form, and the complete breaking 
 down of the nitrogenous substance with the evolution of free nitrogen 
 as a gas. Either of these processes could be a source of infertility. 
 
 ^ 1 1200 
 nI^IIOO 
 ^OOOO 
 
 DEPT/^ y^TWA//C/^ S/JMP/.ES IA^£/?£- 7?1/<£rA/. 
 J^'roG' 6'toI2" I27»I8" I8'to24" 
 
 JS Da YSi_Goo£^ 
 
 /SDoys- PoorSo//. 
 
 Fig. 20.— Diagram showing the ammonification of peptone in 15 days in samples of soil from plat 350 (good 
 soil) and from plats 330 and 340 (poor soil), Truckee-Carsou Experiment Farm. 
 
 The evolution of free nitrogen was determined by measuring the 
 nitrogen gas produced from i)eptone-nitrate solutions at intervals of 
 7 and 15 davs. The results are rather erratic, as is shown in Table 
 VIII. 
 
 Table VIII. — Denitrification by samples of soil from plats 330, 340, and 350, Truckee- 
 
 ( 'arson Experiment Farm . 
 
 No. of 
 plat. 
 
 Denitrification. 
 
 
 Gas formed in— 
 
 
 Depth of 
 soil. 
 
 
 Character 
 of soil. 
 
 
 
 
 
 7 days. 
 
 15 days. 
 
 
 
 Inches. 
 
 Per cent. 
 
 Per cent. 
 
 
 330 
 
 0-6 
 
 30 
 
 35 
 
 Poor. 
 
 
 ()-12 
 
 1 
 
 10 
 
 
 
 12-18 
 
 2 
 
 5 
 
 
 
 18-24 
 
 o 
 
 5 
 
 
 340 
 
 0-6 
 
 35 
 
 40 
 
 Do. 
 
 
 6-12 
 
 40 
 
 40 
 
 
 
 12-18 
 
 20 
 
 25 
 
 
 
 18-24 
 
 30 
 
 40 
 
 
 350 
 
 0-6 
 
 2 
 
 7 
 
 Good. 
 
 
 6-12 
 
 1 
 
 3 
 
 
 
 12-18 
 
 1 
 
 5 
 
 
 
 18-24 
 
 20 
 
 20 
 
 
 211 
 
32 
 
 SOILS OF THE TEUCKEE-CAESON lEEIGATION PEOJECT. 
 
 Table IX shows the difference between the good and poor soils in 
 regard to total numbers and distribution of bacteria. The difference 
 in the floras is more strikingly brought out when we consider the 
 difference in the colonies from the difl'erent soils. The plates from 
 the 6-inch and 12-inch layers of plats 300 and 310, which show low 
 numbers, chiefly contained peculiar colonies surrounded by a wine- 
 colored diffusible pigment. The colony itself was but slightly colored 
 and, surrounded as it was by this pigment, produced a very striking 
 appearance on the plates. One plate from plat 310 was apparently a 
 pure culture of this organism. Such a plate obtained from soil where 
 the growth or flora is almost always rich and varied is very rare, and 
 is the only unusual condition thus far encountered that seems to cor- 
 relate consistently with the unusual conditions of infertility. This 
 peculiar colony was never seen on soils from the fertile spots, and the 
 fact that it was so predominately present in the infertile soils and in 
 those strata in which the peculiar black layer occurred certainly in- 
 dicates that further study should be made of this point. Microscopic 
 examination of the colony showed that it was a micrococcus associated 
 with a mold. 
 
 Table IX. — Total number of bacteria present in 1-gram samples of soil from plats 
 300, .310, S:iO, 330, 340, and 350, Truckee- Carson Experiment Farm. 
 
 No. of 
 plat. 
 
 Depth of 
 soil. 
 
 Number of 
 bacteria 
 per gram. 
 
 Character 
 of soil. 
 
 
 Inches. 
 
 
 
 300 
 
 0-G 
 
 458,400 
 
 Poor. 
 
 
 6-12 
 
 45,000 
 
 
 
 12-18 
 
 48,900 
 
 
 
 18-24 
 
 178,500 
 
 
 310 
 
 0-G 
 
 1,930,500 
 
 Do. 
 
 
 (1-12 
 
 729,000 
 
 
 
 12-18 
 
 15,900 
 
 
 
 18-24 
 
 409,500 
 
 
 320 
 
 0-6 
 
 507,000 
 
 Ctood. 
 
 
 6-12 
 
 351,000 
 
 
 
 12-18 
 
 419,000 
 
 
 
 18-24 
 
 429, (.MIO 
 
 
 330 
 
 0-6 
 
 1,3.'?5,000 
 
 Poor. 
 
 
 6-12 
 
 915,000 
 
 
 
 12-18 
 
 S40, 000 
 
 
 
 18-24 
 
 1,197,000 
 
 
 3-10 
 
 0-6 
 
 4,200,000 
 
 Do. 
 
 
 6-12 
 
 525,000 
 
 
 
 12-18 
 
 4,620,000 
 
 
 
 18-24 
 
 .3,780,000 
 
 
 350 
 
 0-6 
 6-12 
 
 672,000 
 
 (iood. 
 
 
 12-18 
 
 636,006" 
 
 
 
 18-24 
 
 210,000 
 
 
 CONCLUSIONS. 
 
 (1) Nitrifying, denitrifying, and ammonifying bacteria are well 
 distributed and universally present in the soils of the Truckee-Carson 
 Irrigation Project and become physiologically active if favorable con- 
 ditions are provided for their development. 
 
 211 
 
CONCLUSIONS. 33 
 
 (2) The lack of proper decay and huinificatioii oi" organic matter in 
 many of the unproductive soils is due either to unfavorable bacterial 
 conditions brought about by certain i)hysical and chemical conditions 
 or to an unusual bacterial flora. 
 
 (3) The nitrifying bacteria in the soils of Fallon, Nev., are active 
 at greater depths than in eastern soils and also seem to be unusually 
 virile in solutions, although the data on these points are not con- 
 clusive. 
 
 (4) In general, the conditions at Fallon, as in any arid region, favor 
 nitrification, which frequently becomes intense; the conditions rarely 
 favor denitrification. Lack of nitrification, therefore, will not be a 
 Hmiting factor in crop production, nor is there evidence of overnitrifi- 
 cation or injury from excessive quantities of nitrate. Humification 
 studies are probably of paramount importance. 
 
 211 
 
INDEX 
 
 Pagp. 
 
 Apar, beef, medium for development of bacteria 9, 24 
 
 Alkali, black. See Sodium carbonate. 
 
 relation of chlorids and sulphates to nitrifying power 21-22 
 
 Annnonification, definition of term , 7 
 
 measurement of power of soil flora at Fallon, Nev 30, 31 
 
 methods of determination in soil studies at Fallon, Nev 9, 30 
 
 Ammonium sulphate, use in soil studies at Fallon, Nev 10, 12-22, 27, 29 
 
 Analysis, chemical, methods employed in soil studies at Fallon, Nev 10-11, 
 
 26-27, 30, 31 
 
 Bacteria, colonies peculiar to certain soils at Fallon, Nev 32 
 
 counts, methods used in soil studies at Fallon, Nev 9, 10, 26-27 
 
 nitrifying, comparative action in soil and in solution, at Fallon, Nev. 30 
 number and distribution, relation to character of soil, at Fallon, 
 
 Nev : 24-25, 32 
 
 Black alkali. See Sodium carbonate. 
 
 Brown, P. E., and Lipman, J. G., on methods and results of soil studies 9, 30 
 
 Calcium sulphate, effect upon soil samples at Fallon, Nev 26, 27-28, 29 
 
 Chemical anaylsis. See Analysis, chemical. 
 
 Chester, F. D., on the bacteriological analysis of soils 24 
 
 Clay, colloidal, affected by calcium sulphate and gypsum at P'allon, Nev 26 
 
 occurrence in soil samples at Fallon, Nev 10 
 
 Conclusions of bulletin 32-33 
 
 Decomposition, organic, product peculiar to poor soil at Fallon, Nev 26 
 
 Denitrification, definition of term 7, 31 
 
 methods of study employed at Fallon, Nev 11, 22-24, 31 
 
 Dipotassium phosphate, use in peptone solutions at Fallon, Nev ^ 9 
 
 Dunham's peptone solution. See Peptone, Dunham's solution. 
 
 Extract, soil, method of preparation 10 
 
 Failyer, G. H., and Schreiner, Oswald, on analyses of soils 11 
 
 Fallon, Nev., locality of investigations in soil bacteriology. . . 7, 8, 11, 18, 20, 24, 25, 33 
 
 Filtration of soil extracts, Fallon, Nev - 10 
 
 Gypsum, effect upon colloidal clays, at Fallon, Nev 26 
 
 Humification, importance of investigations at Fallon, Nev 33 
 
 Introduction to bulletin 7-8 
 
 Investigations, bacteriological, methods employed at Fallon, Nev 8-11, 
 
 22, 26-27, 30, 31 
 Jensen, C. A., determination of chlorids and sulphates in soil at Fallon, Nev. . . 11, 16 
 
 Lipman, J. G., and Brown, P. E., on methods and results of soil studies 9, 30 
 
 \'oorheea, E. B., on investigations in soil bacteriology 24 
 
 on bacteriological investigations 9 
 
 use of dried blood as a source of nitrogen 30 
 
 Lohnis, F., on bacteriological investigations 9, 24 
 
 Magnesium sulphate, use in peptone solutions at Fallon, Nev 9 
 
 Methods of bacteriological investigation. See Investigations. 
 
 Micro-organisms, relation to soil study at Fallon, Nev , 7, 8-9 
 
 211 35 
 
36 SOILS OF THE TRUCKEE-CAKSON TliRIGATION PROJECT. 
 
 I'age. 
 
 Nitrate formed from nitrite, at Fallon, Nev 29 
 
 Nitrification, definition and method of study, etc., at Fallon, Nev 7, 10-11 
 
 of soil samples in solution at Fallon, Nev 12-25, 27-30 
 
 Nitrite formed from ammonia, at Fallon, Nev ., 28 
 
 Nitrogen, free, relation to presence of bacteria at Fallon, Nev 22, 31 
 
 nitric, quantity originally present, in soil samples at Fallon, Nev. . 8. 12-20 
 
 symbiotic and nonsymbiotic fixation, definition 7 
 
 determination, at Fallon, Nev. 11 
 
 Omelianski and Winogradsky, formula for fluid culture medium 19, 27, 28 
 
 Peptone, ammonification in soil samples at Fallon, Nev 30, 31 
 
 Dunham's solution, use in denitrification studies at Fallon, Nev 11, 22 
 
 solutions, composition, used at Fallon, Nev 9 
 
 Potassium chromate, use in determining chlorids at Fallon, Nev 11 
 
 nitrate, ingredient of peptone solution used at Fallon, Nev 11 
 
 Remy, Theodor, on bacteriological investigations 9 
 
 Rogers, S. J., and Scofield, C. S., on description of Truckee-Carson Experi- 
 ment Farm 8 
 
 Schreiner, Oswald, and Failyer, G. H., on analyses of soils 11 
 
 Scofield, C. S., on description of Truckee-Carson Experiment Farm 8 
 
 Silver nitrate, use in determination of chlorids at Fallon, Nev 11 
 
 sulphate, use for removal of chlorids at F'allon, Nev 11 
 
 Sodium carbonate, presence in soils at Fallon, Nev 26, 28 
 
 chlorid, use in peptone solutions at Fallon, Kev 9 
 
 Soils, eastern and western, comparison of properties 12, 25, 33 
 
 methods of treatment of samples at Fallon, Nev 8-11, 22, 26-27, 30, 31 
 
 nitrification at different depths at Fallon, Nev 7, 12-20 
 
 outline of plan of investigations at Fallon, Nev 7-8 
 
 typical, detailed study at Fallon, Nev 25-32 
 
 Sulphate of ammonia. Sre Ammonium sulphate. 
 
 Syme, W. A., on method of estimating nitrates 11 
 
 Truckee-Carson Experiment Farm. See Fallon, Nev. 
 
 Urea, use in removal of nitrites from nitrates at Fallon, Nev 11 
 
 Voorhees, E. B., and Lipman, J. G., on bacteriological investigations 24 
 
 Winogradsky and Omelianski, formula for fluid culture medium 19, 27, 28 
 
 211 
 
 (J