INDEX 



Absolute specific gravity of minerals, 

 112. 



of soil, 113. 



of soil particles, 113. 

 Absorption by the soil, 349. 



causes, 355. 



formation of insoluble substances, 

 358. 



influence of chabazite, 356. 



influence of colloids, 165, 359, 360. 



influence of organic matter, 150, 365. 



influence of silicates, 363. 



influence of zeolites, 355. 



influence on soil analysis, 340. 



insolubility of absorbed substances, 

 354, 358. 



of ammonia, 366. 



of carbon dioxide, 366. 



of gases, 366. 



of heat, 300. 



of nitrogen and oxygen, 367. 



of phosphoric acid, 357. 



relation to temperature, 367. 



relation to drainage, 368. 



relation to productiveness, 368. 



selective, 362. 



time necessary, 353. 

 Absorptive power of different plants, 



414. 

 Absorbed bases, solubility of, 354. 

 Abundance of common minerals, 11. 



of plant-food elements, 5. 

 Acetic acid secreted by roots, 408. 

 Acid, a flocculating agent, 159. 



in plant juices, 336. 



rocks, 7. 



soils, 375. 



soils caused by ammonium sulfate, 

 499. 



test for carbonates, 388. 

 Acidity and climate, 382. 



and colloids, 165. 



and forests, 380. 

 and sulfur, 382. 

 and plants indicating, 382. 



Acidity, effect on phosphate fertilizer, 

 519. 



relation to bacteria, 436. 



relation to fertilizers, 381. 



quantitative determinations, 389. 



tests for, 386. 

 Acid phosphate, 514. 



for reinforcing manure, 610. 

 Acids formed from fermenting manure, 

 593. 



in plant juices, 379. 



secreted by plant roots, 408. 

 Acme harrow, 677. 

 Adobe, awlian soil, 47, 59. 



described, 61. 



wind origin, 16. 

 ^Eolian soils, deposition of, 58. 



adobe, 61. 



composition of, 60, 62. 



distribution, 61. 



loess, 59. 



sand dunes, 63. 

 Aeration and denitrification, 456. 



and toxic materials, 133. 



effect of drainage on, 631. 



effect on nitrification, 452. 



influence on decay, 129. 



promoted by soil organisms, 422. . 

 Aerobic bacteria, 433. 



bacteria and decay, 444. 



fermentation of manure, 592. 

 Agencies of rock decay, 14. 

 Agricere in soil, 275, 472. 

 Air of the soil, 475. 



analyses, 478, 139. 



carbon dioxide, 139, 478. 



composition of, 477. 



control of, 486. 



effect of organic matter on, 139, 476. 



effect of soil moisture on, 476. 



effect of texture, 475. 



effect of tillage, 487. 



function of, 480. 



movement of, 483. 



volume, 475. 



749 



