INDEX 



Ablation swamp, 30 

 Absolute specific gravity, 175 

 Absorbents, factor in conserving 



manure, 165 



Absorption and radiation of heat, 



effect of, on soil temperature, 302 



Acclimated seed, desirable on dry 



land, 255 



Accumulations in pastures, aid in 

 maintaining organic-matter con- 

 tent, 160 



Acid, chromic, method of determina- 

 tion of organic matter, 154 

 phosphate, 402 



Acids, decomposition of rocks by, 11) 

 carbonic, hydrochloric, nitric, 



sulfuric, 20 

 Acre-inches, 1!)2 



Adaptation of region to dry farm- 

 ing, factors in, 238 

 evaporation, 241 

 rainfall, 238 

 soils, 241 

 Adol>e, 65 



Adsorption by colloids, 132 

 Aeration and soil air, chapter on, 



309 



affecting bacteria, 320 

 aided by drainage, 223 

 or soil ventilation, 311 



accomplished by atmospheric 

 pressure, changes in, 311 

 diffusion, 311 

 removal of water, 311 

 temperature changes, 312 

 tillage, 313 

 wind movement. 313 

 Aftonian Inter-glacial Stage, 46 

 Agassi/, F,ake, 38 



extent of, 46 

 Agencies of weathering, chemical, 11) 



physical. 12 



Agricultural provinces, 383 

 Agriculture, dry-land, chapter on, 



238 



permanent, 389 

 Air in soils, amount of. 309 



convection currents of, source of 

 loss of heat, 296 



Air in soils, composition of. 310 



use of, 309 

 Alfalfa, completely killed by heaving, 



226 



crop for dry land. 253 

 Alkali, area, absence of vegetation 



on, 286 



black, neutralization of, 281 

 effect of irrigation on rise of, 



281 

 on foliage of apricot trees, 



283 



on plants, 282 

 kinds of, 280 

 land, growth of barley on. partly 



and fully reclaimed, 288 

 reclaimed, wheat on, 289 

 lands, and their reclamation, 



chapter on, 278 

 utilization and reclamation 

 of, by removal of alkali 

 salts,' 285 

 growing alkali - resistant 



crops, 2S5 

 neutralizing black alkali, 



286 

 plowing deep and turning 



alkali under, 286 

 retarding evaporation, 285 

 limit for germination and 



growth, 284 

 origin of, 278 



resistant crops, growing of, 285 

 rise of, prevented bv cultivation, 



286 



drainage, 226 



salts, removal of. by cropping, 

 draining, flooding, leaching, 

 scraping, 287 



soils of humid regions, reclama- 

 tion of, 290 



spot, beginning of, 279 

 turning under of, 286 

 Alluvial soils, 38 

 Alluviation by glacial stream. 62 

 Altitude, affecting organic content of 



soils, 145 



Ammonia, effect on flocculation, 137 

 Ammon iff cation, 318 



419 



