48 



DIVISION OF WATER RESOURCES 



The migration of alkali salts through the soil, either upward or 

 downward, is dependent upon the movement of soil water, in both direc- 

 tion and amount. In the presence of a water table within the reach 

 of capillary action, this movement ordinarih' is upward and when there 

 is high evaporation there is a rapid concentration of salts at or near 

 the surface. If the movement of salts was always in one direction, 

 many fields would soon be ruined for production of crops. Fortunately, 

 heavy rains and the surface application of irrigation water tend to 

 carry the salts downward. 



In the soil tanks at Santa Ana, soil alkali accumulated during the 

 dry season on the surface of those tanks having high water tables. In 

 some cases white deposits were noticeable. During the wet season of 

 1931-32, these deposits were carried downward into the soil by penetra- 

 tion of rainfall, and as the tanks were dismantled in May. 1932, much 

 of the alkali had little opportunity to return to the surface. Exceptions 

 occurred in Tanks Xos. 7, 8, and 9, in which the water tables were but 

 1 foot from the surface and a high concentration of salts was redeposited 



TABLE 9 



ALKALI SALT CONCENTRATIONS AND pH VALUES OF COMPOSITE SOIL SAMPLES 

 FROM VARIOUS DEPTHS IN SOIL MOISTURE TANKS AT THE SANTA ANA AND 



SAN BERNARDINO STATIONS- 



' Samples for analysis were collected during June, 1932. 



