INDEX 433 



North Dakota, rotation in, 4 IS Plant food drawn from the soil by 



Northern slope vs. southern slope, 34 average yields of different 



crops, 420 



Oats and buckwheat as soil im- m ter , as : *J .. ... 



*4.9 m an " lands ineffective with- 



/) *- . . OQQ 



Obstructions in drains, to prevent, , 9J", w< .' * 



OOQ locked up in soils, 283 



* 



Okiaho ti Son In' 41S 



Oregon, rotation in, 414 *. 410 



not fertih'ty, 281 



Peat and muck soils, needs of, S90. pebbles as, 25 



Peat, formation of, 47 soils exhausted of, 284 



Peat soils, 60 soil a storehouse of, 282 



crops for, 62 stones as, 25 



Pebbles as plant food, 25 value of different manures, 



Pennsylvania, rotation in, 414 349 



Phosphoric acid, available, 370 trade value of, 375 



cost of, 383 Plants as soil builders, 7, 8, 10, 53 



forms of, 370 do they excrete, 318 



insoluble, 371 enrich soils, 21 



phosphate meal, 381 excrete poisonous wastes from 



reverted, 372 roots, 320 



soluble, 370 how they drink, 77 



sources of, 379 leguminous, definition of, 329 



acid phosphate, 383 for soils lacking nitrogen, 329 



basic slag, 381 used for green manures, 329, 



bone boiled and 334 



steamed, contents, soil-building, check erosion, 



380 29 



dissolved bone, 382 Bermuda grass, 292 



dissolved boneblack, brome grass, 293 



contents, 380 Lespedeza, 293 



dissolved rock, 383 sanitation by, 320 



phosphate slag, con- water needed by, 76 



tents of, 381 what they feed upon, 45 

 plain superphosphate, Plow across slopes to check erosion, 



383 295 



raw bone, contents,379 beam, 131 



rock phosphates, con- beam wheel, 133 



tents of, 381 clevis, 133 



superphosphates, 382 coulter, 132 



Thomas slag, contents disk, 139 



of, 381 early American, 115 



Pine barrens, 51 essentials of a good, 131, 133 



Pits, cement, to save manures, 355 evolution of the, 114-117 



Planker, how to make, 178 gang, 139 



use of, 179 how deep to, 122 



Planking, benefit of, 178 jointer, 132 



Plant food, 25, 45 landside, 137 



air as, 29 mouldboard, 131 



available only in certain point, 133 



forms, 283 share, 133 



