INDEX OF SUBJECT MATTER 



585 



Soil air, carbon dioxide of, 250. 



general characteristics, 247. 



composition data, 248, 250. 



control of, 261. 



general composition of, 247. 



movement of, 258. 



resume of, 262. 



types of, 249. 



volume of, 257. 

 Soil amendments, forms of lime, 363. 



organic matter important as, 124. 

 Soil analysis, alluvial and upland, 49. 



arid and humid soils, 31. 



determination of organic matter, 

 112. 



glacial soils, 57. 



granite soil, 33. 



good and poor soils, 326. 



humus determination of, 115. 



humus in California soils, 120. 



humus in Nebraska soils, 120. 



lime requirement of soil, 355. 



limestone soil, 33. 



loess soils, 63. 



marine soils, 52. 



mechanical, 67. 



nitrogen in California soils, 120. 



nitrogen in Nebraska soils, 120. 



nitrogen in soils of United States, 

 118. 



organic matter in Nebraska loess, 

 , 120. 



organic matter in Minnesota soils, 

 119. 



organic matter in soils of United 

 States, 117. 



peat and muck, 44. 



residual soils, 41, 52, 57. 

 Soil class, discussion of, 79. 



determination from a mechanical 

 analysis, 84. 



practical determination of, 83. 

 Soil colloids, absorption by, 265. 



as influenced by plant roots, 297. 



generation of, 132. 



importance of, 135. 



influence of, 135. 



resume of, 138. 

 Soil color, cause of, 36. 



significance of, 36. 

 Soil erosion and its control, 204. 



types of, 205. 



Soil exhaustion, discussion of, 309. 



possibility of, 308. 



time for, 309. 

 Soil extraction, a method of studying the 



soil solution, 279. 

 Soil fertility, defined, 554. 



effect on transpiration, 192. 



factors involved in maintenance, 554. 



importance of nitrification to, 423. 



influence of plants and animals on, 

 23. 



maintenance program of, 560. 



relation of sulfur to, 468. 



sources of knowledge, 554. 

 Soil formation, forces of, 16. 



general statement of, 29. 



glacial action, 18. 



influence of carbonation, 26. 



influence of climate, 30. 



influence of hydration, 26. 



influence of solution, 27. 



oxidation and deoxidation, 24. 



processes classified, 16. 



special cases of, 32. 



temperature changes, 21. 



water action, 17, 19. 

 Soil heat, importance of, 223. 



influence of on the soil, 224. 



loss of by conduction, 240. 



loss of by evaporation, 240. 



loss of by radiation, 240. 



transfer of, 238. 

 Soil humus, determination of, 115. 

 Soil minerals, importance of, 6. 



list of, 5. 

 Soil moisture, conservation of, 219. 



data of, 179. 



effect on conductivity of heat, 236. 



effect on heat capacity, 233. 



effect on transpiration, 191. 



importance of amount in plowing, 

 146. 



influence of on the soil solution, 

 286. 



optimum for efficient tillage, 150. 



optimum for plants, 200. 



relation of to granulation, 142. 

 Soil mulch and moisture conservation, 

 221. 



relation of to capillary movement, 

 175. 



use of, 218. 



