Water in the Soil 



71 



suffering from a lack of moisture. If the fields were 

 kept well plowed, more of this water would soak into 

 the soil and could later be used by the plants when dry 

 times come. If more water soaks into the layer of tilled 

 soil than it can retain by its capillary properties, it is 

 absorbed by the sub-soil and may finally percolate 

 down to the layer of rock or clay and flow off to form 

 springs. It is much better for the farmer if the surface 

 soil and the sub-soil are well supplied with water. The 

 rains are usually not abundant in the season when they 

 would be most beneficial in increasing the yield of the 

 crops. This fact suggests all the more strongly the im- 

 portance of studying the ways that may be used to : 



1. Increase the ready absorption of the rainfall; 



2. Increase the water-storage power of the soil occu- 

 pied by the roots (f 100) ; 



3. The efficiency of mulches in conserving the mois- 

 ture. 



105. Increasing the Water- Storage Power of the soil 

 may be accomplished in two ways: (a) By deep break- 

 ing. This increases the pore space in the soil by making 

 the granules of soil smaller. They, therefore, have more 

 capillary space (U 95). Breaking should be done in 

 the fall so that the winter rains may t}e absorbed. 



40. Diagram to illustrate the effect of ideal plowing. The compactness of 

 the soil is indicated by the density of the shading. Before plowing, there is a 

 compact surface crust (s), below which the soil grows less compact as we go 

 deeper; after plowing, this compact mass is broken up into a loose, friable 

 mass of soil-crumbs, or floccules, with a consequent increase in the bulk of 

 the furrow-slice (/s); compacted plow sole at pi. Modified after Hilgard. 



