CHAPTER V 



THE AMOUNT AND MEASUREMENT OF WATER REQUIRED 

 FOR IRRIGATION 



THERE is no problem of greater or more fundamen- 

 tal importance to the irrigator than that which deals 

 with the amount of water required to produce paying 

 yields when correctly and economically handled in the 

 production of crops of various kinds. The problem is 

 an extremely complex one, which has received as yet 

 very inadequate systematic study on a rational basis, 

 such as the exigencies of the case demand. 



THE MAXIMUM DUTY OF WATER IN CROP 

 PRODUCTION 



A given quantity of water applied to the soil, either 

 in the form of rain or by methods of irrigation, renders 

 its greatest service when the whole of it is taken up by 

 the roots of the crop growing upon the ground, leaving 

 none to be lost by surface evaporation or by percolation, 

 unless, indeed, some soil leaching is indispensable to 

 unimpaired fertility. Were it practicable to establish 

 and maintain field conditions of culture which would 

 insure that all water lost from the soil should take 



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