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, 80 



in relation to fertilizing elements, 



187, 206 

 fertilizers, 206 

 grain farming, 344 

 liming, 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 liming, 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 limestone, acid, 242, 248 

 glacial, defined, 15, 18 

 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 



liming, first step in, 230 



rotations best for, 274 

 in dry climates, 44, 378 

 in humid climates, 44 

 kinds of, 14, 15, 24 

 lacustrine, 15, 21 

 leaching of, 349, 351 

 light, defined, 15 

 loess, defined, 15, 22 

 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 in crop production, 

 92 



forms of, 93 



how held in soils, 93 



importance of, in soil, 89 



in relation to germination, 49 



in soil medium, 12 



laboratory exercises on, 105, 107 



most important form of, 93 



movement of, 95-98 



mulches to conserve, 103, 104, 313 



robbed by weeds, 104, 380 



supply in soils, 98-100 

 mulch, cultivation to maintain, 104, 313 



defined, 102 



how conserves moisture, 103 



laboratory exercises on, 105, 106 . 



self-forming, 104 



value during dry periods, 104 

 of, in dry-farming, 380 



what constitutes a good, 103 

 needing phosphates, 199 

 needs, determining, 355 



chemical analysis for, 355 



factors to consider in, 355 

 of many kinds, 9, 14, 15, 24 

 of national interest, 1 

 organisms and fertility, 171. (See Soil 



bacteria) 

 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, 106 

 relation to seeds, 49 

 rich, defined, 66 

 rocks in relation to, 39 

 series, defined, 24 

 sour, 45, 229 



source of mineral elements, 35 

 standards for comparing, 72 

 structure, defined, 13 



and mulch formation, 104 



destroyed by plowing, 54, 322 



illustrated, 13 



in clay management, 322 



organic matter relations, 266 



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 



laboratory exercises on, 57, 59, 132 



of clay soils, 322 



marsh soils, 302 

 sands, 309 



plant-growth relations, 51, 77 

 texture, defined, 13 



basis for soil classification, 13 



clay of fine, 13 



drainage relations, 120 



dry-farming relations, 378 



factor in capillarity, 6 



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 teepage relations, 95 



