ROOT SYSTEMS IN ARID SOILS 



89 



condition of the soil permits the entrance of air, which 

 helps to purify the soil atmosphere and thereby to 

 make the conditions more favorable for root develop- 

 ment. Consequently it is to be expected that, in 



Fig. 25. Corn roots. 



arid regions, roots will ordinarily go to a much greater 

 depth than in humid regions. 



It is further to be remembered that roots are in 

 constant search of food and water and are hkely to 

 develop in the directions where there is the greatest 

 abundance of these materials. Under systems of 

 dry-farming the soil water is stored more or less 

 uniformly to considerable depths — ten feet or more 

 ■ — and in most cases the percentage of moisture in 



