394 



INDEX 



Potash, fertilizers, uses of, 203, 204 

 Potassium, amount removed by crops, 62, 

 63,69 



carbohydrate relations, 64 



chloride, fertikzer, 202 



defined, 30, 32 



distribution of, in plants, 63 



fertility relations, 187, 360 



fertilizers. (See Potash) 



function of, in plants, 55 



in feeds, 383^ 



protein relations, 64 



sulfate, 202 



supply in soils, 70, 71 

 in subsoils, 72 

 Potato, cultivation for, 168 



elements removed by, 63 



for clay soils, 325 



for marsh lands, 305 



for sandy soils, 316 



high yield of, 82, 87 



response to fertilizers, 188 



rotations for, 276 



scab, disease, 265 

 lime and, 233 

 rotation a remedy, 205 

 Press driUs, 156, 314 

 Profitable crop production, 369-375 



acre profits, 371 



fertihzer, determining, 371 



liming, 231, 232 

 Profits and fertilizers, 207 



basis on which to compute, 372 3 



determining from fertilizers, 371 



per acre, 371 



relation of, to cost of production, 375 

 Protein and nitrogen in crops, 63 

 Pulverized limestone, 238 

 Pulverizers, 152-155 

 Pyrite, defined, 40, 



Quartz, defined, 40 

 Quartzite, defined, 39 

 Quicklime for liming, 243 



Rainfall, at right time, 91 

 amount evaporated, 91 



lost, 100 



used by crops, 100 

 map of the United States, 101 

 Rape for green manure, 192 

 Raspberries, elements removed by, 69 

 Residual soil, defined, 15 



origin and extent, 16 

 Rice, rotation for, 280 

 Rich soil, defined, 66 

 Ridge terraces, defined, 288, 289 

 River bottom erosion, 287 

 Rocks, affecting soils, 39 

 classes of, 39 

 defined, 40 

 field studies on, 46 

 laboratory exercises on, 46 

 Rock phosphate, fertilizer, 197, 198 



availability of, 197 



choice of, 201, 202 



deposits of, 198 



for black, prairie soils, 201, 202 



for clay soils, 324 



for depleted silt loams, 326 



for marsh soils, 200, 300 



for reinforcing manure, 220, 222 



for sands, 313 



how to use, 198 



in relation to decay, 173 



Rock phosphate, results with manure, 220. 

 222 

 vs. acid phosphate, 202 

 weathering, defined, 6-9 

 products of, 41 

 Rock-forming minerals, 40 



laboratory exercises on, 45 

 Roller and tilth, 54, 154-156 

 for marsh soils, 302 

 for sandy soils, 313 

 Rollers, 154, 155 

 Roosevelt Dam, 129 

 Root, growth and drainage, 110 

 hairs, 68, 69 

 of corn plant, 53 

 maggots, 256 

 systems of plants, 68 

 Root-knot, 257 

 Rotation. (See Crop rotation) 



chart, 331 

 Rothamsted Experiment Station, 374 

 Rowen, defined, 195 

 Rye, elements lemoved by, 63 

 for green manuie, 192 

 for marsh soils, 305 

 for sands, 310 

 rotations for, 276 



Salt of the sea, 43 



Salts, and germination, 49 



in soil medium, 13 



products of nitrification, 175 

 of rock weathering, 41 

 Sand grains, defined, 12 



soil, defined, 14 

 Sands, advantages in cropping, 309 



blowing of, 314 



crop rotations for, 317 



crops for, 315 



dune, 309 



fertilizers for, 310-313 



field studies on, 320 



grain drills for, 315 



green manuring for, 194, 310 



home projects on, 320 



improvement of, 311 



kinds of, 14, 309 



lime for, 240, 245, 312 



liming, 312 



management of, 309-320 



manure for, 310 



mixed fertilizers for, 313 



moisture supply in, 313 



nitrogen fertilizer for, 311 



organic matter important in, 310 



pasture on, 317 



peat for improving, 315 



phosphates for, 312 



plowing, 315 



potash for, 312 



problems in cropping, 310 



rock phosphate for, 313 



rotation improves, 266 



rotations for, 276 



seed-bed preparation, 313 



soybeans for, 312, 316 



stock farming on, 329 



subsoiling, 313 



sugar beets for, 317 



tiling, 120 



types of soils, 309 



of farming on, 318 



vegetation indicates value of, 309 



velvet bean for, 310 



water-holding power of, 98, 313 



