viii Contents. 



CHAPTER X. 



SOIL TBMPERATUBB. 



PAGE. 



TEMPERATURE AT WHICH GROWTH BEGINS 212 



BEST SOIL TEMPERATURE 212 



Influence on rate of germination, p. 214 ; Effect on root pressure, 



p. 215 ; On the formation of nitrates, p. 215. 



CONDITIONS INFLUENCING SOIL TEMPERATURE 215 



Specific heat of soil, p. 215 ; Moisture in soil, p. 216 ; Color of soil, 



p. 217 ; Topography, p. 218 ; Texture of surface, p. 218 ; Tillage, 



p. 219 ; Chemical changes, p. 219 ; Rains and percolation, p. 



219; Rate of evaporation, p. 220. 



MEANS OF CONTROLLING SOIL TEMPERATURE 221 



Rolling, p. 221 ; Early thorough tillage, p. 222 ; Thorough drainage, 



p. 222. 



CHAPTER XI. 



OBJECTS, METHODS AND IMPLEMENTS OF TILLAGE. 



OBJECTS OF TILLAGE 223 



TILLAGE TO DESTROY WEEDS 223 



Best time, p. 224 ; Best tools, p. 225 ; For early killing, p. 225 ; 

 For intertillage, p. 226. 



TILLAGE TO MODIFY TEXTURE . 231 



Soil texture and tilth, p. 231 ; Importance of good tilth, p. 233. 



liow TEXTURE AND TILTH ARE DEVELOPED 233 



The uses of harrows, p. 234 ; The planker, p. 236 ; The roller, p. 

 237 ; The plow, p. 238 ; How may puddle soils, p. 239 ; May 

 correct texture and improve tilth, p. 239. 



FORMS OF PLOWS 239 



Must be adapted to the soil, p. 240 ; Sod plow, p. 241 ; Pulverizing 

 plow, p. 242; Mellow soil plow, p. 242. 



DRAFT OF PLOWS 243 



English and American trials, p. 243 ; Draft of sod plow with and 

 without coulter, p. 243 ; Sod compared with stubble plow, p. 

 244 ; Influence of moisture on draft, p. 244 ; Draft of sulky 

 plow, p. 245 ; Line of draft, p. 246 ; Scouring of plows, p. 247. 



GARB OF PLOWS 247 



When not In use, p. 247 ; Keeping in form, p. 247. 



SUBSOIL PLOW 250 



OBJBCTS, METHODS AND TIMES OF PLOWING 250 



Depth of plowing, p. 250 ; Best condition of soil for, p. 251 ; Treat- 

 ment after plowing, p. 252; Plowing for corn in the fall, p. 

 252 ; Plowing sod, p. 252 ; Plowing under manure, p. 253 ; Plow- 

 Ing under green manure, p. 253 ; Early fall plowing, p. 254. 



