490 



INDEX 



Potash, sources, 308. 

 Potash of soils, 176. 

 Potassium essential to plants, 13. 

 Potatoes, depth of rooting, 104. 

 Potato fertilizer, 345. 

 Prairie soils, 77. 

 Primary minerals, 149, 150. 

 Productive value, 427. 



calculation of, 423. 



of feeds, 422. 

 Protamins, 357. 

 Proteids, 356. 



classes, 357. 



digestion, 394. 



effect on milk production, 470. 



form fat, 440. 



value for maintenance, 438. 



productive value, 422. 



value in feeding, 475. 

 Protein, 346, 355. 



digestion of, 405. 



used in work, 453. 



value for maintenance, 438. 



value for work, 455. 

 Proteoses, 357. 

 Ptyalin, 392. 

 Putrefaction, 207. 

 Pyrite, 155. 

 Pyroxene, 151. 



Quartz, 150. 

 Quicklime, 255. 



Raffinose, 367, 370. 



Rain, nitrogen in, 48.' 



Rainfall relation to yield of crops, 



125- 

 Ration, calculation of, 476. 



improving, 477. 



reducing cost of, 4/8. 



restricted, 435. 

 Rennin, 393. 

 Respiration calorimeter, 415. 



chamber, 414. 



Respiratory methods, 454. 

 Rhamnose, 366. 

 Rice bran, 391. 

 Rivers, carrying power, 66. 

 River deposits, 67. 

 Rock, crystalline, 63. 

 Rocks, final weathering products 

 of, 60. 



glassy, 63. 



granite, 65. 



igneous, 63. 



metamorphic, 63. 

 Rocks, solution of, 57. 



weathering of, 54. 



stony, 64. 



Rocky Mountain soils, 78. 

 Rothamsted, foundation of, 10. 

 Root absorption, 198. 

 Roots, ash of, 21. 



acidity, 180. 



depth of penetration, 102. 



need for oxygen, 43. 



solvent action, 200. 



root tubercles, 212. 

 Roughage, 390. 



productive value, 425, 480. 

 Ruminants, 392. 



Saccharic acid, 366. 

 Saliva, 393. 

 Salt, 428. 

 Sand, 80. 

 Sands, 73, 86. 



crops for, 92. 



particles of, 83. 

 Sandstone, 73. 

 Saponification, 351. 



value, 353. 



Secondary minerals, 149, 151. 

 Sedentary soils, 61. 

 Seeds, ash of, 21. 



classes, 379. 



need oxygen, 43. 

 Serpentine, 153. 



