TABLE OF CONTEXTS xi 



CHAPTER XII 



PAGES 



THE WATER OF THE SOIL IN ITS RELATION TO PLANTS . 243-263 



Relations of water to the plant, 167 The water 

 requirement of plants, 168 Factors affecting trans- 

 piration, 169 Effect of crop and climate on transpira- 

 tion, 170 Effect of soil moisture on transpiration, 171 

 Influence of fertility on transpiration, 172 Effect of 

 texture on transpiration, 173 Actual amounts of water 

 necessary to mature a crop, 174 Role of capillarity in 

 the supplying of the plant with water, 176 Influence 

 of water on the plant, 176 Availability of the water in 

 the soil, 177 Unavailable soil water, 178 The wilting 

 coefficient of plants, 179 Determination of the wilting 

 point, 180 Calculation of the wilting point, 181 Re- 

 lation of texture to the wilting point, 182 Available 

 and superavailable water, 183 Optimum moisture for 

 plant growth, 184. 



CHAPTER XIII 



THE CONTROL or SOIL MOISTURE ..... 264-288 



Run-off losses, 185 Percolation losses, 186 Methods 

 of checking loss by run-off and leaching, 187 Evapo- 

 ration losses, 188 Methods of checking evaporation 

 losses, 189 Mulches for moisture control, 190 Kinds 

 of mulches, 191 The functions of a mulch, 192 The 

 soil mulch versus the dust mulch, 193 Formation of a 

 mulch, 194 Depth of a mulch, 195 Re'sume' of mulch 

 control, 196 Water saved by a mulch, 197 Effect of 

 mulches other than on moisture, 198 General useful- 

 ness of a mulch, 199 Other practices affecting evapo- 

 ration losses, 200 Fall and early spring plowing, 201 

 Rolling, 202 Shelters, 203 Level cultivation, 204 

 Plants, 205 Summary of moisture control, 206. 



CHAPTER XIV 



SOIL HEAT 289-326 



Relation of heat to germination and growth, 207 

 Chemical and physical changes due. to heat, 208 



