CHAPTER XVIII 

 SOIL WATER: HOW IT IS LOST; HOW IT MAY BE HELD 



The operation of loosening and stirring the soil usually 

 is spoken of as tillage or cultivation. Heretofore four 

 reasons have been advanced in support of tillage : it in- 

 creases the root room for the plant ; it admits air into the 

 soil so that plant food may be more readily prepared ; it 

 secures oxygen for plant roots ; and it destroys weeds. 



THE RESULT WHEN WATER IS SECURED AND HELD 

 The annual rainfall where these sugar beets were grown was but 20 inches 



We must not overlook two other tillage operations that 

 stand out prominently in any rational treatment of the 

 soil. These are : the rainfall is enabled to enter the soil 

 easily ; the loss of water by evaporation is checked. 



While each of these operations deserves careful atten- 

 tion, the last two are open to more gentle treatment and 

 to more sensitive consideration than the operations pre- 

 viously described. 



Transpiration: the exit through the leaves. We have 

 learned that roots gather moisture and carry it into the 



