INDEX 



349 



94; in soil solution, 81, 196; total 

 and available, 92, 93. 



Plants, crowding of, in seed bed, 302. 



Plowing, depth of, 43; energy re- 

 quired for, 293 ; fall, 41 ; spring 

 41 ; influence of, on soil, 291 ; in- 

 fluence of, on moisture, 294; influ- 

 ences nitrification, 291. 



Pore space, 13. 



Potash fertilizers, 212; use of, 222; 

 of commercial fertilizers, 240; salts, 

 218. 



Potash, in soils, amount of, 214; 

 sources of, 215; soluble and in- 

 soluble, 84; and lime, joint use of, 

 222; muriate of, 217; sulphate, 

 217; removed in crops, 213. 



Potassium compounds of soil, 78. 



Potato, fertilizers for, 264; food* 

 requirements of, 264; soils, 22. 



Preliminary trials with fertilizers, 248. 



Priestley, 2. 



Property of soils, 12; modified by 

 farming, 115. 



Pulverized lime rock, 227. 



Pulverizing soils, 295. 



Quartz, 64. 

 Questions, 327. 



Rainfall and crop production, 29. 

 Rape, food requirements of, 266. 

 Reaction of soils, determination of, 



3i9- 



References, 340, 344. 



Relation of crop and soil type, 303. 



Reverted phosphoric acid, 202. 



Review questions, 327. 



Roberts, 43, 175, 293. 



Rock disintegration, 55, 68. 



Rocks, composition of, 64, 69; prop- 

 erties of, 318. 



Rolling of soils, 40, 294. 



Root crops, fertilizers for, 266. 



Roots, action on soil, 255, 276. 



Rotation, and soil water, 277; and 

 weeds, 280. 



Rotation of crops, 273, 284; prin- 

 ciples involved, 274; length of, 281 ; 

 problems, 284; and farm labor, 

 278; and humus, 275; and insects, 

 280; and soil nitrogen, 276. 



Salt as a fertilizer, 229. 



Sand, grades of, 14, 15. 



Schlosing, 8. 



Schubler, 5. 



Seaweeds as fertilizers, 231. 



Sedentary soils, 62. 



Seed, amount of, per acre, 303. 



Seed bed, preparation of, 291. 



Seed residues, 151. 



Sheep manure, 171. 



Silicon and silicates, 74. 



Silt particles, 17. 



Size of soil particles, 14. 



Skeleton of soils, 14. 



Small fruits, fertilizers for, 271. 



Small manure piles, 183. 



Sodium compounds of soils, 80. 



Sodium nitrate, 154. 



Soil, composition of, 97, 98; con- 

 servation of fertility, 285; ex- 

 haustion, 274, 304; management, 

 303; particles, study of, 319; sam- 

 pling of, 86, 87 ; solution of, 80, 196; 

 types, 21. 



Soils and agriculture, relation of, 305 ; 

 crops suitable for, 303. 



Soot, 230. 



Specific gravity of soil, 13. 



Specific heat of soil, 48. 



Sprengel, 5.^ 



Spring plowing, 41. 



Stassfurt salts, 216. 



Stock farming and fertility, 288. 



Storer, 75, 148. 



Strand's plant ash, 231. 



Street sweepings, 232. 



Stutzer, 152. 



