INDEX OF SUBJECT MATTBE 



583 



Rational fertilizer practice, 497. 

 Recovery of nutiients in farm manure, 



516. 

 Reduction, as affected by plant roots, 



297. 

 Reduction of nitrates in soil, 424. 

 Reinforcement of farm manure, 527. 

 agricultural value of, 529. 

 balancing injauence, 529. 

 conserving: effects, 529. 

 Eesidual influence of manure, 531. 

 Residual soils, age of, 39. 

 analysis of, 33, 41. 

 chemical composition of, 52, 57. 

 compared with glacial soils, 57, 

 colors of, 32, 39. 

 formation of, 38. 

 from specific rocks, 39. 

 location of in U. S., 41. 

 organic content, 41. 

 Residues in soil from differential dif- 

 fusion, 294. 

 Resistance of plants to alkali, generalized 



table of, 338. 

 Resistance to alkali by various plants, 



data on, 338. 

 Reversion of mono-calcium phosphate in 



soil, 457. 

 Reverted phosphoiic acid, defined, 456. 

 Rock phosphate, as a reinforcement for 

 manure, 528. 

 changes in soil, 456. 

 compared with acid phosphate, 458. 

 composition, 456. 

 composted with manure, 462. 

 influence of organic matter on, 460. 

 Ohio results on, 462. 

 source, 456. 



use of in sulfur composts, 406. 

 Rocks, igneous, sedimentary and meta- 

 morphic, 4. 

 soil forming, 3. 

 Rodents, macro, soil organisms, 384. 

 Rollers, actions of, 148. 

 Roots of higher plants, a type of macro- 

 organism, 386. 

 production of carbon dioxide by, 



production of exudates by, 296. 

 Rooting habit of plants, in relation to 



alkali toxicity, 336. 

 Rotation, farm manure and the, 632. 



Sampling of soil, method of, 311. 

 Sand dunes, nature of, 64. 

 Season, mfluence on soil solution, 283. 

 Sedentaiy soil, explanation of term, 28. 

 Sediment carried into ocean, 46. 

 Selective absorption by soils, nature of, 

 269. 

 types of, 269. 

 Selection of a commercial fertilizer, fac- 

 tors to consider, 482. 

 Sheet erosion and its control, 205. 

 Size of colloidal particles, 128. 

 Slope, influence on soil temperature, 229. 

 influence upon absorption of solar 

 insolation, 229. 

 Sod, influence on nitrate accumulation, 



427. 

 Sodium chloride as a soil amendment, 

 380. 

 presence of in alkali, 333. 

 Sodium nitrate, changes in soil, 448. 

 character of, 448. 

 composition of, 448. 

 retention of by soils, 321. 

 origin of, 448. 

 source of, 448. 

 Soils, absorption by, 263. 



absorptive capacity of, 266. 

 acid nature of, 345. 

 acquisition of nitrogen by, 428. 

 addition of sulfur to by precipita- 

 tion, 469. 

 jBolian, 61. 

 alkali, 328. 

 alluvial, 46. 



amendments used on, 363. 

 ammonification in, 412. 

 amounts of capillary water in, 166. 

 amount of gravity water in, 177. 

 available water of, 198. 

 average composition of, 12. 

 bulk analysis of, 311. 

 capacity of to retain nitrates, 321. 

 capillary capacity for water, 163. 

 capillary movement of water in, 168. 

 capillary water of, 159. 

 cause of acid condition of, 351. 

 changes of lime in, 369. 

 chemical analysis of water extract 



from, 320. 

 coUuvial, 45. 

 color of, 36. 



