396 



INDEX 



Soil fertility, defined, 79 



affected by harmful agents, 255, 



262 

 determined by chemical analysis, 



355 

 diseases affecting, 255, 261 

 factors determining, 80 

 in maintaining, 271 

 to be considered, 355 

 grain farming and, 344 

 home projects on, 353 

 how to test, 80 

 illustrated, 82 

 indicated by crop yields, SO 

 in relation to fertilizing . elements, 

 187, 20G 

 fertihzers, 206 

 grain farming, 344 

 hming, 229, 231, 250 

 soil organisms, 171 

 stock farming, 345 

 systems of farming, 343 

 lowered by acidity, 229 

 maintained in grain farming, 344, 



347 

 maintained in stock farming, 345 

 maintaining, 206, 271 

 not restored by hming, 250 

 problems on, 354 

 regulated by liming, 250 

 surveys, exercises, 353 

 unfavorable factors, 83 

 work problems on, 353 

 field studies on, 27, 46, 73 

 formation of, 5-9, 16-22, 40-45 

 forming processes, 6-7 

 from Hmestone, acid, 242, 248 

 glacial, defined, 15, IS 

 grains. {See Particles) 

 heavy, defined, 15 

 how described, 22 

 humid vs. arid, 44, 378 

 improvement, general, 87 



crop rotations for, 263-274 

 by legumes, 180 

 green manuring for, 194, 195 

 home projects on, 368 

 in clay management, 321 

 in marsh management, 294 

 in sand management, 310 

 in silt loam management, 325 

 hming, first step m, 230 

 rotations best for, 274 

 m dry cHmates, 44, 378 

 in humid climates, 44 

 kinds of, 14, 15, 24 

 lacustrine, 15, 21 

 leaching of, 349, 351 

 lig-ht, defined, 15 

 loess, defined, 15, %% 

 mapping, 22-25 



exercises on, 27 

 management increase crops, 2 

 in England, 2 

 in Germany, 2 

 in France, 2 

 marine, defined, 15, 21 

 mechanical compostion of, 15 

 mineral, defined, 41 

 moisture, 89-132 (See Soil water) 

 amount soils give up, 91 

 capillary rise of, 96 

 conservation of, 100, 313, 380 

 control of. 100 

 cultivation to conserve, 104,313,380 



Soil moisture, factor m crop production, 



forms of, 93 

 how held m soils, 93 

 importance of, m soil, 89 

 in 1 elation to germination, 49 

 in soil medium, 12 

 laboiatoiy exercises on, 105, 107 

 most important form of, 93 

 movement of, 95-98 

 mulches to conseive, 103, 104, 313 

 robbed by weeds, 104, 380 

 supply m soils, 98-100 

 mulch, cultivation to maintain, 104, 313 

 defined, 102 



how conserves moisture, 103 

 laboratory exorcises on, 105, 106 

 self-forming, 104 

 value duung dry periods, 104 



of, m diy-f aiming, 380 

 what constitutes a good, 103 

 needing phosphates, 199 

 needs, detei mining, 355 



chemical analysis for, 355 

 factors to consider in, 355 

 of many kinds, 9, 14, 15, 24 

 of national interest, 1 

 organisms and fertihty, 171. (See Soil 



bacteiia) 

 origin of, 5 



our nation's problem, 2 

 particles, names of, 11 



composition of, 29, 30 

 not plant food, 61 

 size of, 11, 12 

 porosity of, exercises on, 100 

 relation to seeds, 49 

 rich, defined, 60 

 rocks m relation to, 39 

 series, defined, 24 

 sour, 45, 229 



source of mineral elements, 35 

 standards for compaiing, 72 

 structure, defined, 13 



and mulch foimation, 104 

 destroyed by plowing, 54, 322 

 illufetiated, 13 

 in clay management, 322 

 organic matter 'relations, 260 

 renewed, 54, 322 

 rotation relations, 266 

 seed-bed relations, 54, 135 

 tilth relations, 54, 322 

 survey, 22-25 

 temperature, 48, 109 



and germination, 49 



drainage relations, 48, 109 



field studies on, 60 



laboratoiy exercises on, 57, 59, 132 



of clay soils, 322 



maish soils, 302 

 sands, 309 

 plant-growth relations, 51, 77 

 texture, defined, 13 



basis for soil classification, 13 

 clay of fine, 13 

 drainage lelations, 120 . 

 dry-farming relations, 378 

 factor in capillarity, L6 



in water-holding, 98, 99, 102 

 fertility relations, 40, 72, 81 

 influence on capillarity, 96, 97 

 laboratory exercises on, 26 

 liming relations, 247 

 percolation and seepage lelations, 95 



