INDEX 



397 



Soil texture, plowing relations, 142, 147, 148 

 sand of coarse, 13 

 seed-bed relations, 54, 135, 155, 322 

 soil classes determined by, 14 



mulch relations, 103, 104 

 tilth relations, 54, 135, 322 

 unchangeable, 13 

 tight, denned, 112 

 transported, denned, 15 

 transporting agents, 15 

 tropical, 45 

 type, denned, 24 

 washing. (See Soil erosion) 

 water, 89 



laboratory exercises, 105, ICG 

 (See Soil moisture) 

 weight of, 71 



exercises on, 27 

 when formed, 5 



why some deficient in K and P, 40 

 Soybeans, elements removed by, 63 

 for green manuring, 192 

 for sands, 312, 316 

 illustrated, 193 

 response to liming, 233 

 Spading disk harrow, 152 

 Spray irrigation, 130 

 Springs, why some dry up, 285 

 Stock farming, defined, 343 



crop rotation in, 329 

 grain and, compared, 343, 344 

 popularity of, 344, 345 

 soil fertility relations, 343 

 Strawberries, elements removed by, 69 

 Stubble land, defined, 138 

 plows for, 141 

 plowing, 138 



Sub-humid climate, defined, 42 

 Sub-irrigation, 130 

 Sub-main, tile, defined, 121 

 Subsoil, defined, 11 



plant-food elements in, 72 

 tight, defined, 112 

 Subsoiling, 145, 147, 148 



for sandy soils, 313 

 Subsurface drainage, 113 



covered drains for, 116, 117 

 open ditches for, 115 

 Succession of crops, defined, 280 

 Sugar beets, desirable type, 55 

 a heavy feeder, 64 

 elements removed by, 62, 67 

 for marsh soils, 305 

 for sands, 317 

 need potash, 263 

 response to liming, 233 

 root system of, 68 

 rotation for, 2SO 

 where grown, 280 

 Sugar cane, rotation for, 280 

 Sulfate of ammonia, 196 



of potash, fertilizer, 202, 203 

 Sulfur, defined, 30, 32 



as fertilizing element, 33 

 function of, in plants, 56 

 Summer fallowing, defined, 153 



in rotation, 277 

 Superphosphate fertilizer, 199 

 Surface drainage, defined, 112 

 plow furrows for, 114 

 surface runs for, 114 

 use of spade for, 114 

 run, defined, 114, 123 



with tile, 123, 124 

 Swamp, defined, 39 



Sweet clover, illustrated, 193, 323 

 for alkali soils, 258 

 for clay soils, 323 

 for green manuring, 193 

 for soil improvement, 193 323 



Syenite, defined, 39 



Systems of farming, 343 



in relation to fertility, 343-353 

 of tile drainage, 121, 122 



Tankage, fertilizer, 196 

 Temperature. (See Soil temperature) 

 Terracing, defined, 288 

 Testing soils for needs, 355-368 



(See under Fertilizers) 



(See under Lime) 

 Thomas slag, fertilizer, 197, 198 

 Tile (drain), defined, 117 



drainage, defined, 117, 126 



better than open ditches, 122 

 for alkali soils, 131, 258 

 for alkali spots, 44, 111 

 for "bogus" spots, 302 

 for heavy clays. 322 

 for irrigated lands, 131 

 for marsh soils, 110, 304 

 for slopes, 95, 111 

 gridiron system of, 121, 122 

 herringbone system of, 122 

 in relation to toxins, 262 

 natural system of, 120, 121 

 parallel system of, 121, 122 

 profitable, 124, 125 

 systems of, 121 

 tools for, 118 



drains, explained, 117 



better than ditches, 122 

 distance apart to lay, 119 

 how to cover, 119 

 how to make, 117, 119 

 how they work, 120, 124 

 laboratory exercises on, 133 

 must have fall, 117 

 protected outlets for, 122, 123 

 with surface runs, 123 

 Tillage, general discussion, 135 



in relation to toxins, 262 



objects of, 137 



of clay soils, 212 



of dry-farming lands, 378, 380 



of marsh soils, 295, 297 



of sands, 313, 315 



principles governing, 137 



relation to erosion, 287 



seed-bed preparation, 138 



tools, 136-169 

 Tilth, defined, 48 



cultivation and, 135 



factors determining good, 135 

 in development of good, 54 



fertility relations, 356 



field studies on, 60, 88 



full meaning of good, 52-54 



good, defined, 48 



green manure and, 190 



importance of good, 49 



influences plant growth, 51 



laboratory exercises on, 58, 59 



liming favors, 230 



of clay soils, 321 



organic matter and, 266 



poor, defined, 48 



rotations to improve, 266 



seeding and planting relations, 156 

 Timothy, elements removed by, 63 



