CHAPTER VII 



THE CHAEACTER OF WATER FOR IRRIGATION 



THE characteristics which determine the suitability 

 of water for the purposes of irrigation must depend 

 upon the chief objects for which the water is used : 

 whether it is to control temperature, as in the case of 

 winter -meadows and in cranberry culture ; to supply 

 plant -food, as in the case of summer water-meadows ; 

 to meet the simple need of water for the transpiration 

 of the growing crop, or to deposit sediments for the 

 purpose of building up the surface of low -lying areas, 

 as in the case of warping. 



TEMPERATURE OF WATER FOR IRRIGATION 



Where one of the prime objects in the use of water 

 for irrigation is to stimulate plant -growth, the warmer 

 the water is within the natural ranges of temperature 

 the better are the results. According to Ebermayer, 

 when the temperature of the soil in which a crop is 

 growing has been lowered to from 45 to 48 F., phys- 

 iological processes are brought nearly to a standstill 

 in it, and the maximum rate of growth does not be- 

 come possible until after the soil temperature has 

 risen above 68 to 70. It is plain, therefore, that if 

 large volumes of cold water were applied to the soil at 



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