Index 



310, 315, 335, literature con- 

 cerning, 292-294; effect on 

 toxicity of copper solutions, 

 426; modifying influence of 

 tilth on effects of copper, 

 438. 



Soil colloids. See Colloids, soil. 



Soil columns of California, inves- 

 tigation, 1; ammonification, 

 6-10; nitrifying powers, 10- 

 13; nitrogen fixation, 13-15; 

 summary, 16-19; significance 

 of absence and presence of 

 Azotobacter, 15, 20. 



Soils in the arid region. See 

 Arid regions, soils. 



Soils of California, bacterial ac- 

 tivity, 179; organic nitrogen 

 in, 260; color affected bv hu- 

 mus, 265, 267, 273; depth, 

 272; humic phosphoric acid 

 in, 268, 269; kinds of: adobe 

 clay, 183, 186, 187, 197, 206, 



214, 216, 217, 218, 220, 223, 

 237, 250, 251, 263, 266, 269; 

 alkali ("white ash"), 196, 

 266; clav-loam, 192, 194, 214, 



215, 216', 217, 219, 223, 250, 

 266, 269; delta loam, 203; 

 dry bog, 197; lowland (river 

 alluvial and tule marsh), 203, 

 230, 231, 232, 235, 250, 251, 

 266, 269; red mesa and "bed- 

 rock" lands, 189, 190, 199, 

 207, 209, 233. 234. 266; sandv 

 loams. 192, 193, 206, 207, 217 

 220, 223, 230, 231, 236, 250 

 269; slate and granite, 208 

 209; absorption of sodium 

 301, 315, of metals, 551-553 



Humus (humus content), 272 

 basis for commercial valua- 

 tion, 274; combined with 

 nitrogen, 273, with soluble 

 mineral plant food, 274; dis- 

 tribution, 273; occurrence, 

 274; percentage in surface 

 soils, and in tule swamps, 273; 

 relation to soil diffusion, 313; 

 retardation, 273; source, 273. 



Soils. See also Alkali soils; Am- 

 monia; Ammonification; Arid 

 regions; Colloids; Humus; 

 Nitrification; Nitrogen; So- 

 dium carbonate; Sodium chlor- 

 ide; Sodium sulfate. 



Solution culture method, faults, 

 535. 



Squash, growth in soils contain- 

 ing coj)per as carbonate, 434. 



Strejitothrix s])., culture experi- 

 ments, 142. 



Studies in Ammonification in Soils 

 by Pure Cultures, 141. 



Studies on the Phenoldisulphonic 

 Acid Method for Determining 

 Nitrates in Soils, 21. 



Studies upon Influences Affecting 

 the Protein Content of 

 Wheat, 63; points investigat- 

 ed, 63; methods, 65. 



Tailings, chemical composition, 

 478; effect on growth of alf- 

 alfa, 474-478. 



Tankage, culture experiments, 

 142, 149, 150, 151, 152. 



Tobacco, influence on of nutrient 

 solution, 348-362._ See Nutri- 

 ent solution. See also Nitro- 

 gen; Phosphorus; Potassium. 



Toxic effects of magnesium car- 

 bonate on ammonification, 41, 

 and on nitrification, in soils, 

 45. 



Utah Agricultural Experiment 

 Station, study of relation of 

 moisture to protein content 

 of wheat, 75, 76. 



Volatilization, effect in ammoni- 

 fication experiments, 47. 



Water cultures, plants grown in: 

 copper content, 417, 418; tox- 

 icity of copper solutions, 448, 

 464, to roots, 419; stimula- 

 tion of cop]ier, 422. 



Wheat, The Protein Content of, 

 Studies upon Influences Af- 

 fecting, 63. 



Wheat, California (Pacific Coast), 

 protein content: low, 64, 103, 

 influences affecting: climate, 

 65, 67, 103. 109, 110, 117, va- 

 riety of wheat, 66, 67, tend- 

 ency of varieties toward con- 

 stancy of change in type 

 seeded, 69, individuality of 

 plant, 67, moisture (irriga- 

 tion), 75, 76, 114, time of 

 seeding, 86-93, time of har- 

 vesting, 93, 94-98, 98-102, 

 111-114. 117, sunshine, 10.3- 

 109, 111, reducing of atmo- 

 spheric temperature, 117-119, 

 fertilizers, 120-125, nitrogen, 

 122-123, phosphates, 124; pot- 

 ash, 124, green manure crops, 

 125; localities selected for 

 experiments, 69; tendency to 

 change from gluten to starch, 

 69, 75, 81, 87, 93; reversion 

 from starch to gluten, 74; 



[594] 



