568 



INDEX OF SUBJECT MATTER 



Alkali, origin of, 331. 



resistance of crops to, data on, 338. 



rise of as influenced by irrigation, 

 339. 



white, 329. 

 Alkali lands, handling of, 340. 

 Alkali salts, listed, 330. 

 Alkali soils, defined, 328. 



importance of, 328. 

 Alkali spots, nature of, 332. 

 Alkali tolerance by plants, factors of, 



336. 

 Alkali vegetation, 340. 

 Alluvial fans, 47. 

 Alluvial soils, chemical composition, 49. 



classified, 46. 



deltas, 47. 



fans, 47. 



flood plain, 47. 



importance of, 49. 



origin of, 46. 

 Aluminum, hydrolysis of in soil, 348. 



relation of to soil acidity, 347. 



relation to the reversion of acid 

 phosphate, 457. 

 Alunite as a fertilizer, 465. 

 Amino acids defined, 106. 



in farm manure, 510. 

 Amides defined, 106. 

 Ammonia in rain water, data on, 429. 

 Ammonification, conditions for, 414. 



influence of protozoa on, 387. 



nature of, 412. 



organisms of, 413. 



products of, 413. 



reactions of, 414. 

 Ammonifying efficiency of soil, determi- 

 nation of, 414. 

 Ammonium salts, utilization by higher 



plants, 415, 450. 

 Ammonium sulfate, changes in soil, 449. 



character of, 449. 



composition of, 449. 



source of, 449. 

 Amounts of fertilizer to apply, 492. 

 Amounts of lime to apply, 368. 

 Analysis of plant tissue, method of, 102. 

 Analysis of soil, bulk, 311, 314. 



carbon in, 113, 114. 



extraction, dilute acids, 317. 



extraction, strong acids, 316. 



extraction, with water, 319. 



Analysis of soil, humus, 115. 



lime requirement of, 355. 



minerological, 76. 



nitrogen in, 311. 



organic matter of, 115. 



value of, 323, 326. 

 Apatite in soil, 6. 



Application of farm manure, amounts, 

 526. 



evenness, 526. 



incorporation in soil, 526. 

 Arid soils, biological activity in, 32. 



chemical analysis of, 31. 



humus content of, 120. 

 Assimilation of nitrates by soil organ- 

 isms, 426. 



importance of, 428. 

 Available water in soil, 198. 

 Availability of nitrogen fertilizers, 454. 



of phosphate fertilizers, 458. 

 Azofication, amount of nitrogen fixed, 

 433. 



energy for, 432. 



organisms of, 432. 

 Azotobacter ehroococcum in soil, 431. 



B. Radicicola, amount of nitrogen fixed 

 by, 437. 



availability of nitrogen fixed by, 437. 



function of, 434. 



importance of, 436. 



inoculation of the soil, methods of, 

 439. 



nature of organism, 435. 



nodules of, 434. 



relation to host plant, 435. 



strains of, 434. 

 Bacteria, decomposition of organic mat- 

 ter by, 103. 



increase of in frozen soil, 394. 



influence on aeration in soils, 393. 



injurious to higher plants, 396. 



method of counting in soil, 392. 



multiplication of, 391. 



production of carbon dioxide by, 252. 



relation of to alkali, 332. 



relation to liming, 395. 



relation of moisture to, 393. 



relation to organic matter in soil, 

 394. 



relation to soil acidity, 395. 



relation to soil temperature, 394. 



