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, denned, 39 

 Sedentary soils, 15 

 Sedimentary rocks, 39 

 Sediments, amount in streams, 17 

 carried into Gulf of Mexico, 18 

 soils from, 17 

 source of, 17 



Seed bed, 48, 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 planting, 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 constitutes 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 svstem 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 necessary to correct all, 249 



organic acids cause of, 237 



plants indicating, 234 



prevalence of, 23? 



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 reservoir, 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, 26, 27 

 colluvial-soil, 15, 22 

 components of, 11 

 common meaning of, 11 

 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 



effect 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, 18, 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 



