120 IRRIGATION PRACTICE 



be of distinct value in diminishing the rate of loss of 

 water from the soil. Consequently it follows, also, that 

 on alkali soils the rate at which water is transpired is 

 smaller than on soils that are free from alkali. This 

 may, in a small measure, account for the fact that even 

 cropped alkali lands remain rather moist throughout the 

 season. 



If all this be true, however, it is within the power of 

 the farmer so to maintain the soluble material in the 

 soil as to permit the plant to draw water from the soil 

 at the slowest possible rate. By proper methods of 

 cultivation whereby plant-food is set free, by the appli- 

 cation of commercial fertilizers, of manure, or by innocu- 

 ous salts, such as the abundant sodium sulfate, it is 

 possible to maintain the soil solution in a high degree of 

 concentration and thereby secure for the plant the neces- 

 sary foods at a very slow rate. This fundamentally impor- 

 tant factor in the economical use of water by plants, has 

 received in the past practically no attention, but is now 

 becoming more generally recognized. 



85. Plowing.-^ Among the cultural processes that have 

 for their purpose the reduction of the rate of loss of water 

 from the soil, none is more important than the ancient 

 art of plowing, which is the fundamental practice in all 

 agriculture. From the point of view of the irrigation 

 farmer, and the saving of soil moisture, plowing has dis- 

 tinct advantages. First, it permits the easier descent of 

 water into the soil and consequently a more rapid and more 

 uniform distribution throughout the soil. This results 

 in a smaller rate of loss. Second, thorough and careful 

 plowing at the right time of the year, preferably in the 

 fall, gives every soil activity new freedom, thereby releas- 

 ing more plant-food and rendering the soil solution more 



