THE INFLUENCE OF IRRIGATION 227 



to accumulate, to render the soil barren. Another stream would 

 carry to the soil in the same time and under the same conditions 

 over fifteen tons of salt. 



One application of such water may not kill plants, but what 

 would a number of applications do? Moreover, one application 

 may be sufficient to materially decrease nitrification in such a soil. 

 This would then be reflected by decreased yields. 



It is, therefore, evident that the intelligent use of irrigation 

 water is a complex problem which requires a knowledge of the 

 chemical, physical, and biological properties of the soil, together 

 with a knowledge of the composition of the water and its influ- 

 ence upon the chemical, physical, and biological changes going on 

 in the soil. One user of irrigation water may make of it a tool 

 for making the desert bloom like the rose, whereas another user 

 may through its use transform the most productive fields into a 

 barren waste. 



