INDEX OF SUBJECT MATTER 



Ability of plants to grow on poor soils, 



299. 

 Abrasion defined, 18. 

 Absorption by litter, 521. 

 Absorption, by soils explained, 263. 



capacity of soils to retain nitrates, 

 321. 



due to soil colloids, 265. 



effect of on soil acidity, 352. 



effect of texture on, 267. 



importance of in soils, 273. 



of litter in stable, 521. 



selective by soils, nature of, 269. 



selective by soils, types of, 269. 

 Absorption by soils, capacity for, 266. 



causes of, 264. 



defined, 263. 



importance of, 273. 



influence of time on, 269. 



law of, 269. 



relation to acidity, 274. 



relation to the soil solution, 276. 



selective, 269. 



types of, 263. 

 Absorption of solar insolation, as influ- 

 enced by atmosphere, 226. 



as influenced by color, 228. 



as influenced by slope, 229. 



as influenced by soil, 226. 

 Absorptive capacity of different crops, 



301. 

 Acid phosphate, 456. 



changes in soil, 457. 



character, 456. 



compared with rock phosphate, 458. 



composition, 456. 



manufacture, 456. 



reinforcement of manure with, 528. 

 Acidity, as influenced by absorption, 274. 



development of by hydrolysis, 348. 



production of by selective absorp- 

 tion, 270. 



soil, nature of, 345. 

 Acids, production of by plant roots, 296. 

 Actinomyces in soils, character of, 389. 



Actinomyces in soils, importance of, 389. 



number of, 289. 

 Addition of nutrients to soil, 556. 

 Additions to and losses from soil under 



various types of farming, 558. 

 Adobe, inportance of, 64. 



origin of, 64. 



wind formation of, 21. 

 jEolian soils, adobe, 64. 



loess, 61. 



sand dunes, 64. 



volcanic dust, 65. 

 Aeration of soil, effect on nitrification, 

 418. 



importance in soil, 256. 



influence on bacteria in soils, 393. 

 Agglutination of colloids, 131. 

 Agricultural lime, defined, 363. 



forms of, 363. 

 Agricultural value of farm manure, 513. 

 Air of the soil, carbon dioxide of, 250. 



composition of, 247, 248. 



composition data, 248, 250. 



effect of oxidation on, 254. 



general characteristics of, 247. 



importance of oxygen in, 256. 



practical modification of, 261. 



movement of, 258. 



types of, 249. 



volume of, 257. 

 Alkali, black, 329. 



composition of, 329. 



conditions affecting influence of, 338. 



control of, 343. 



control of by means of gypsum, 342. 



effect of concentration of on crops, 

 337. 



effect on crops, 334. 



effect on soil organisms, 335. 



eradication of, 341. 



eradication of by means of drainage, 

 341. 



influence on nitrification, 421. 



in river water, 332. 



in irrigation water, 334. 



567 



