Contents. vii 



CHAPTER VII. 

 MOVEMENTS OF SOIL MOISTURE. 



PAQB. 



GRAVITATIONAL MOVEMENTS 158 



Percolation, p. 158 ; Rate through sand, p. 159 ; Through soil, p. 



159 ; Through dry soil, p. 1GO. 



CAPILLARY MOVEMENTS 161 



Rise In capillary tubes, p. 161 ; Rise In soils, p. 163 ; Obserred 



hight In moist soil, p. 165 ; Measurement of maximum night, 



p. 167 ; Rate of rise in wet soil, p. 168 ; In dry soil, p. 168 ; In- 



fluenced by rain, p. 170 ; By farmyard manure, p. 172 ; By 



mulches, p. 173 ; By firming the soil, p. 174. 



THERMAL MOVEMENTS 176 



Hygroscopic soil moisture, p. 175 ; Movements, p. 175 ; Relation to 



size of soil grains, p. 176 ; Amount a soil may absorb, p. 178 ; 



Internal evaporation, p. 179. 



CHAPTER VIII. 

 CONSERVATION OF SOIL MOISTURB. 



MODES OF CONTROLLING SOIL MOISTURE 181 



Late fall plowing, p. 181 ; Late tillage for orchards, p. 182 ; 

 Early fall plowing, p. 182 ; Early spring plowing, p. 183 ; Ef- 

 fectiveness of mulches, p. 185; Frequency of cultivation, p. 

 187 ; Cultivation after rains, p. 190 ; Depth of cultivation, p. 

 191 ; Depth and frequency vary with the season, p. 191 ; 

 Early harrowing of corn and potatoes, p. 192 ; Harrowing and 

 rolling small grain after it Is up, p. 192 ; Mulches other than 

 soil, p. 193. 



SUBSOILING TO SAVE MOISTURE 195 



Increases water capacity, p. 198; decreases capillarity, p. 199; 

 Favors percolation, p. 199 ; More of water available, p. 200. 



DANGER FROM GREEN MANURING 201 



WIND-BREAKS AND HEDGES 202 



CHAPTER IX. 

 RELATION OF AIR TO SOIL. 



NEEDS OF SOIL VENTILATION 204 



Needs of free oxygen, p. 204 ; Flx'lng of free nitrogen, p. 206. 

 PROCESSES OF SOIL VENTILATION 207 



By diffusion, p. 207 ; By changes of soil temperature, p. 207 ; By 

 changes of barometric pressure, p. 208 ; By wind suction, p. 

 208 : By rains, p. 209. 

 WATS OF INFLUENCING SOIL VENTILATION : . . . 209 



Modified by tillage, p. 209; Reduced by rolling, p. 210; Increased 

 by drainage, p. 210 ; Modified by vegetation, p. 211. 



