712 SOILS: PROPERTIES AND MANAGEMENT 



Angeles has a large farm irrigated with sewage water. 

 The same general principles prevail in the use of water 

 as in normal irrigation practice, except that the soil may 

 become clogged and foul from the accumulation of solid 

 material, especially where the idea of disposal over- 

 shadows that of efficient use. This practice is used 

 chiefly for the production of hay and forage. 



DRY-FARMING 



The water supply for irrigation is sufficient for only a 

 small part of the earth's surface which needs such treat- 

 ment. The remainder of this vast area of land having a 

 deficient rainfall must be utilized, if at all, by the most 

 scrupulous and careful conservation and use of the natural 

 rainfall. The growth of crops without irrigation under 

 such conditions is termed dry-farming. 1 It is merely an 

 intensified form of the methods which are recognized 

 as good practice to conserve moisture in more humid 

 regions. 



Dry-farming is based on the principle that the production 

 of dry matter in crops requires only a small part of the 

 water which may be used in one way or another in its 

 growth, and that a large part of that water is lost by sur- 



1 Widtsoe, J. A. Dry Farming. New York. 1910. (Appendix 

 includes a large list of references on dry land farming.) 



MacDonald, Wm. Dry Farming. New York. 1910. 



Campbell, H. W. Soil Culture Manual. Lincoln, Nebiska. 

 1907. 



Chilcott, E. C. Dry Farming in the Great Plains Area. 

 U. S. D. A., Yearbook, pp. 451-468. 1907. 



Briggs, L. J., and Shantz, H. L. The Water Requirement 

 of Plants. Investigations in the Great Plains in 1910 and 1911. 

 U. S. D. A., Bur. Plant Ind., Bui. 284. 1913. Also, the Water 

 Requirements of Plants. A review of literature. U. S. D. A., 

 Bur. Plant Ind., Bui. 285. 1913. 



