THE FUNCTION OF WATER IN AGRICULTURE 251 



all within the memory of recorded history, and the dis- 

 tribution of the rainfall in these treeless areas seems 

 to be in no wise dependent upon the fact that they had 

 no forests within their borders. 



Apparently the escape of forest soil moisture into the 

 air by evaporation is retarded. On the other hand vast 

 quantities are given off from the foliage of the trees. 

 The planting of trees on all areas not suited to the plow 

 is to be encouraged. Fields that lend themselves 

 readily to tillage had better be kept for that purpose. 



