SOIL CHANGES DUE TO IRRIGATION 75 



constituents, and more went into solution during the 

 sixth than during the second period. In all probability, 

 if these successive washings had been continued, they 

 would have resulted in the continuous removal of appre- 

 ciable quantities of valuable soil constituents. The con- 

 tinuous solubility of soils has a very important bearing 

 upon the permanent production of crops on any one soil. 



FIG. 17. Midsummer snow in the tops of the mountains. The source of irrigation 

 water. This water is very pure. 



