Index. 



599 



Pit silos, 423. 



Hank frame, 340. 



I'lanker, use of, 2o6. 



Plant food, essential constituents, 69 ; 

 functions of, 70 ; proportion of total 

 soil, 78 ; amount removed by crops, 79 ; 

 in an acre-foot of soil, 79, 81 ; con- 

 served by early seeding, 201 ; Impor- 

 tance of temperature In development 

 of, 212 ; loss of through weeus. '2-4 : 

 manner of supply to plants, 46 ; de- 

 rived from the air, 554. 



Plants, growth of limited by soluble 

 . 93: breathing of, 142; respira- 

 tory organs of. 1-42. 



ing, silo walls, 398, 402, 403, 406, 

 407. 



Plow. 238 ; as a tool to develop texture, 

 238 ; forms of, 239 ; for sod, 240, 

 241 : soil and function determine 

 form. 240 ; for pulverizing soil, 242 ; 

 for mellow soil, 242 ; draft of, 243, 

 244. 245 ; draft influenced by soil 

 moisture, 244: line of draft in, 246; 

 scouring of, 247 ; care of, 247 ; jointer 

 attachment for, 249; sub-soil form, 

 230. 



Plowing, to conserve *oil moisture, 181, 

 182, is:', ; early for corn and potatoes, 

 185 ; may puddle soils, 239 : to cor- 

 rect texture. 239; depth of, 250; con 

 dition of soil for, 251 ; treatment of 

 ground after, 252 ; for corn in the 

 fall, 2."i 2 sod. 252 ; covering manure, 



green manure, 253: early r'.-ii. 

 254 ; horse power required for. 491. 



Poisons. 12. 



Pore space, of soils. Ill, 233 ; maximum 

 and minimum for spherical grains, 

 109. 111. 114 : influence on water ca- 

 pacity. 114 : of different kinds of soil, 

 114; iniluence 01 s>i.u-^.v.r>iou of on 

 rate of percolation, 115 : method of de- 

 termination, 115: maximum in soils, 

 116 ; shape of. 163, 164 ; necessary for 

 roots, 233 ; in sands and gravels, 

 256 : in soil and clay, 257 : unoccupied 

 In drained sands, 261 : influence of on 

 capacity of wells, 276 ; for materials 

 for concrete, 381. 



Posts, strength of, 330 ; avoiding use of 

 in barns, 374. 



Potash, essential to plant growth, 69; 

 function of, 70 ; amount removed by 

 crops, 79 ; amount in soil, 80 ; in 

 wheat crop, 81. 



Potatoes, amount of water used by, 141 ; 

 early plowing for, 185: best time to 

 cultivate, 192: ridged and flat cul- 

 tivation for, 194. 

 Preemption, rise of ground water due 



to, 260. 



Pressure, relation of to flow of water, 

 262. 208: influence of on capacity of 

 wells, 279: of gases, '10: osmotic, 42 : 

 relation of to volumj of gas 



measurement of osmotic, 43 ; of silage, 

 894 ; of atmosphere, 559 ; of steam, 

 504 ; gage, 511 ; on piston in pumping. 

 547, 548. 



Priming, in engine, 506. 

 Pulley, relation to belts, 545. 

 1'ump, capacity of ou sand point com- 

 pared with open suction pipe, 282 ; 

 cross-head, 575; In gasoline engine, 

 ~>-~> ; suction, 546 ; size of piston, 547 ; 

 rate of discharge, 548 ; relation cl 

 size to discharge pipe, 548 ; double- 

 acting, 550 ; place for cylinder, 551. 

 Pumping, by windmill. 5:n, 5:15 ; rate of. 

 .":;; : power for influenced by size of 

 discharge pipe, 548. 

 Pusey, draft of plows, 243 



Qulncke, distance over which cohesive 

 attraction becomes sensible, 37. 



Rain, bad effect of on animals. 33 ; 

 evaporation of, 33 ; ammonia and ni- 

 tric acid In, 86 ; cultivation after, 

 190; influence of on soil temperature, 

 219 ; effect of on rise of ground water, 

 261. 



Rainfall, relation to storm center. 575; 

 ronditi^^s unfavorable for, 584. 



Ram, hydraulic, 552. 



Respiration, products of, 350, 351 ; 

 amount of air breathed, 353. 



Richthoffen, formation of loess, 64. 



Rivers, formation of soil by, 54, 55. 56, 

 57. 



Roads. 428 ; grade of, 428 ; effect of 

 grade on draft, 428 ; steepest grade 

 admissible, 430; conditions modifying 

 grade. 433 ; draft on different kinds, 

 436, 437, 443 : establishing grade, 444 ; 

 drainage of, 445. relation of water to, 

 446, depth of, 446, place for drains, 

 447,, fall of drains, 447, outlet of 

 drains, 448, size of tile, 448, sur- 

 face, 448 ; slope, 449 ; water-breaks, 

 449 ; texture of road metal, 450. size 

 of material, 451, shape of material, 

 451. cleanness. 452: earth. 452. 477. 

 forming road-bed, 452. 455, util- 

 izing old road-bed, 455 ; on grav 

 elly loam, 455: on clay soil. 4.'.:.: 

 on sandy soil, 456 : use of straw, saw- 

 dust and tan bark, 457 ; gravel for, 

 457; In swampy places. 400: stone, 

 461 ; ancient types, 461 ; macadam, 

 462, construction. 462, 403, road 

 metal for, 464, 465. 400. 40: 

 4<;:>. -spreading rock, 470. thickness 

 of layers. 473. rolling, 47.^. 474, 475; 

 roller, kind, 475 : rock crush. 

 475 ; rock screens. 459. 477 : com 

 bined roads, 477: Tel ford foundation, 

 478 ; culverts, 479 ; maintenance, 480. 



