INDEX 



439 



Soils, temperature, conditions af- 

 fecting, latitude or angle 

 of sun's rays, .304 

 slope, 304 

 specific heat, 298 

 tillage, 307 



water, presence of, 302 

 for growth, 298 

 for vital functions of plants, 



germination, 29(5 

 growth, 297, 298 

 nitrification, 298 

 osmosis and diffusion, 



298 

 influenced by liquid water, 295 



by manure, 294 

 raised by absorption of water 



vapor, 294 



ten -year average, 307 

 texture and structure of, effect 



on erosion, 358 

 timber, 70 



time for heat to penetrate, 300 

 top, 07 



type, defined, 79 

 types, classes and phases in Illi- 

 nois, 1 14 



defined, Illinois, 112 

 internal area of, 182 

 naming of, 113 

 ventilation, sec aeration, 311 

 water of, 180-222 

 water-laid, 33 

 water-logged, 313 

 weight of, 170 

 Sole, plow, 70 

 Solid manure, value of, excreted by 



farm animals, 102 

 Solution, decomposition by, 22 

 Specific heat of water, 187 

 gravity, apparent. 175 



of soil-form ing minerals, 17") 

 real or absolute. 175 

 Sphagnum moss, 27, 28 

 Spring plowing, 344 



wheat, acreage, 1909, 415 

 region, rotation for, 380 

 Stability of soil increased by drain- 

 age, 222 



Stalactites, stalagmites, in cavern. 23 

 Stones, 139 

 Stony loams, 1 10 

 Storm, dust, 54 

 Straw, used in tilling gullies, 370 



Streams, diversion of, for irriga- 

 tion, 258 

 erosion of, 10 

 -laid soils, 38 

 material carried and rolled bv, 



10 

 work of, affected by velocity 



of current. 10 



Strisc, glacial, on rock surface, 43 

 Structure of soil, effect on erosion, 



358 



Sub-provinces, classes, types, sur- 

 veys, chapter on, 112 

 Subsidence method, physical analv- 



sis, 124 

 Subsoil, 08 

 plow, 330 



soil and, chapter on, 07 

 Subsoiling, 345 

 Subsoils, arid and humid compared, 



70 



Substances in solution, effect on vis- 

 cosity, 205 

 Subsurface packing, 247 



soil, 07 

 Sugar beets, returns from thirty 



inches of water, 200 

 Sulfuric acid, decomposition bv, 20 

 Surface, internal, 181 

 soil, 07 

 tension, affecting capillaritv. 



199 



and density of solutions. -JOO 

 Survey, soil, by Bureau of Soils, 



chapter on, 78 

 by Illinois Experiment Sta- 

 tion, chapter on, 112 

 methods of, 118 

 objects of, 1 1 7 

 Surveys, soil. 110 



in different states, 117 

 Swamp, ablation, 30 



land, typical Eastern, 29 

 wet woods. 30 

 Swamps, defined, 27 



river, 28 

 Sweet clover on badlv eroded land, 



301 



plowed under. 172 

 quantity grown per acre, 17.'! 

 Syenite. 7 

 Systems of physical analysis, 124 



Talus. 30 



slope. 32 

 Temperature, chapter on, 293 



