INDEX 



395 



Sands, weight of, 15, 71 

 Sandstone, defined, 39 



soil derived from, 42 

 Sandy loam, defined, 14 

 rotation for, 276 

 Sandy soils, defined, 14 

 kinds of, 309 

 (See under Sands) 

 Schist, defined, 39 

 Sedentary soils, 15 

 Sedimentary rocks, 39 

 Sediments, amount m streams, 17 

 earned mto Gulf of Mexico, 18 

 soils fiom, 17 

 source of, 17 

 Seed bed, 4S, 49, 135, 156 

 good, defined, 54 



favors planting, 156 

 for peat soils. 302 

 for sandy soils, 313 

 preparation of, 48, 138 

 Seeders, 157, 158 

 Seeding and j)lanting, 156 

 Seeds, absorption by, 49 



contact with soil, 49, 156 

 fate of, when planted, 47 

 laboratory exercises on, 47 

 relation to seed bed, 51, 156 

 what constitutefa good, 76, 77 

 Seepage, defined, 95 

 Semi-arid- climate, 49 



soils, 378 

 Shale, defined, 39 

 formation of, 43 

 soil derived from, 42 

 Shavings for bedding, 351 

 Sheet erosion, defined, 286 

 Shells, for liming, 243 

 form limestone, 43 

 origin of, 43 

 Shoe drills, 158 

 Silica, defined, 30, 31 

 Silicon, defined 31 

 Silt, defined, 12 



loam, defined, 146 

 Skinner sj^-stem of irrigation, 130 

 Slate, defined, 39 



soil derived from, 42 

 Smoothing harrow,' 152 

 Sod plowing, 140, 142, 143 

 Sod plows, 141, 144 

 Sodium, defined, 30, 32 



nitrate fertilizer, 196 

 Soil, defined, 5 



acidity, defined, 45, 229 



alfalfa and clover indicating, 234 

 blueberries indicate, 234 

 cause of, 237 

 chemical tests for, 234 

 cranberry indicating, 234 

 crops injured by, 233 

 crops tolerating, 233 

 demonstrations on, 251 

 fertility relations, 229 

 field studies on, 253 

 gypsum for, 244 

 harmful effects of, 229 

 horsetail rush indicates, 236 

 how determined, 233 

 laboratory exercises on, 253 

 land-plaster for, 244 

 lime to correct, 229 

 litmus paper test for, 234 

 lowers fertility, 229 

 low wet lands indicating, 236 



Soil, mild alkali indicating, 236 



mineral acids cause of, '239 

 nature of, 238 

 not harmful to roots, 248 

 not necessaiy to coriect all, 249 

 organic acids cause of, 237 

 plants indicating, 234 

 prevalence of, 237 

 roots not injured by, 248 

 sheep sorrel indicating, 235, 236 

 Truog test for, 234 

 unfavorable to bacteria, 230 

 weeds indicating, 235 

 a complex medium, 12 

 alluvial, defined, 15, 17 

 a re&ervoii, 98 

 bacteria, 171. 



(.See Soil bacteria) 

 affected by liming, 230 

 conditions favoring, 184 

 nodule bacteria, 180 

 non-symbiotic, 178 

 number in soils, 171 

 symbiotic 178 

 barley, 66 

 carried away, 9 

 chemical analysis of, 355, 356 

 collecting for, 358 

 for lime needs, 358 

 for nitrogen, 359 

 for organic matter, 359 

 for phosphorus, 359 

 for potassium, 360 

 how made, 358 

 uses of, 358 

 composition of, 29 



affecting plant growth, 34 

 classes of, 14 

 classification, 14 



on basis of origin, 15 

 on texture, 14 

 on type, 22-24 

 laboratory exercises, 2G, 27 

 eolluvial soil, 15, 22 

 components of, 11 

 common meaning of, H 

 cumulose, defined, 15, 16 

 depletion, defined, 84, 85 



indicated by nitrogen analyses, 359 

 phosphorus analyses, 85, 250 

 in grain farming, 344 

 in stock farming, 345 

 descriptions of, 22 

 erosion, 17, 95, 283 



a serious problem, 283 



causes of, 285 



causing loss of elements, 283, 350, 



351 

 efi'ect of, on irrigation, 284 



on water power, 284 

 field^ studies on, 292 

 grazing in relation to, 286 

 injures crop production, 285 

 injuries resulting from, 283, 284 

 interferes with navigation, 284 

 in the United States, 17, IS, 283 

 kinds of, 286 

 on steep slopes, 285 

 pasturing in relation to, 286 

 prevention of, 287 

 problem in clay management, 324 

 soil organic matter relations, 287 

 projects on, 292 

 exhaustion. (See Soil depletion) 

 factor in plant growth, 47 



