572 



INDEX OP SUBJECT MATTER 



Decay and decomposition defined, 103, 

 410. 

 and putrefaction, in nitrogen cycle, 



410. 

 and putrefaction, organisms of, 411. 

 effect on soil temperature, 239. 

 of farm manure, importance of, 511. 

 of green manure, influence on lime 



and phosphorus, 545. 

 of green manure, influence on nitrate 



accumulation, 543. 

 of green manure, influence on nitri- 

 fication, 544. 

 of green manure, stages of, 542, 

 of organic matter in soil, products 

 of, 110. 

 Decomposition, defined, 17. 



of organic matter in soil, 103. 

 Delta soils, 47. 



Denitrification, use of term, 420. 

 Deoxidation, influence in soil formation, 



24. 

 Deposition, its relation to soil formation, 

 16. 

 relation to lime requirement, 356. 

 Depression of the freezing point, a 

 method of studying soil solu- 

 tions, 280. 

 Determination of soil humus, 115. 

 Determination of soil organic matter, 

 bomb method, 114. 

 chromic acid method, 113. 

 loss on ignition, 112. 

 Di-calcium silicate as a soil amendment, 



380. 

 Diffusion, differential into plants, 292. 

 of nutrients into plants, 291. 

 of soil air, 260. 

 Diminishing returns, law of, 493. 

 Disc plow, influence on soil, 146. 

 Disintegration, defined, 17. 

 Dissociation, defined, 270. 

 Drainage and evaporation at Botham- 



sted, 217. 

 Drainage, importance of, 210. 

 influence of, 210. 

 loss of sulfur by, 404. 

 nutrient losses from soil, 556. 

 qualitative composition of water of, 



304. 

 quantitative composition of water 

 of, 304. 



Drainage, use of in eradication of alkali, 

 341. 



usual type of, 212, 

 Drainage water, carbon in, 402. 



composition data of, 305. 



composition of, at Bromberg, 272. 



importance of study, 178. 



qualitative composition of, 304. 



quantitative composition of, 304. 

 Dried blood, changes in soil, 445. 



character, 445. 



composition, 445. 



source, 445. 

 Earth worms, importance of, 385. 

 Earth's crust, minerals in, 4. 

 Electric arc method of fixing nitrogen, 



452. 

 Electrolyte, defined, 130. 



efltect on colloids, 131. 

 Element in the minimum, 476. 

 Energy necessary for evaporation of 



water, 241. 

 Energy, wave length of, 225. 

 Enzymes, action of, 890. 



defined, 103, 390. 



importance in soils, 103, 

 Eradication of alkali from soils, 341. 



types of, 341. 

 Erosion defined, 18. 



relation to soil movement, 16. 

 Erosion of soil, control of, 204. 



types of, 205. 

 Evaluation of farm manure, 512. 

 Evaporation and drainage at Eotham- 



sted, 217. 

 Evaporation of soil moisture, control of, 

 218. 



energy necessary for, 241. 



influence of on soil heat, 241. 



loss of soil water by, 216. 



water influenced by, 182. 

 Exfoliation in soil formation, 21. 

 Exhaustion of soil, discussion of, 309. 



possibility of, 308. 

 Exosmosis, nature of, 290. 

 Extraction of soils, with concentrated 

 acids, 316. 



with dilute acids, 317. 



with water, 319. 



with water, successive extractions, 822. 

 Exudates, excretion of by plant roots, 

 296. 



