244 SOILS 



opening at the lower end which would need to 

 be closed. 



Irrigation Water from Springs and Wells. 

 Irrigation from springs and wells is of far greater 

 importance in India and in parts of Africa than in 

 the United States; most of our irrigation is done 

 from streams. In eastern United States, however, 

 it is frequently practicable to supplement the 

 deficient rainfall of certain seasons by supplying 

 water from a well or spring, provided the area to be 

 covered is not large. In India a single well waters, 

 on an average, from 3 to 5 acres of arid land. 

 Small springs yielding only two or three quarts per 

 second may be cleared out and should irrigate 

 several acres. It is usually necessary, however, 

 to provide a reservoir when the flow is so small. 

 This may be merely large enough to hold the flow 

 of twenty-four hours. A spring that runs two 

 Quarts per second would discharge 43,200 gallons 

 in twenty-four hours, which could be held in a 

 reservoir forty feet square and three and one-half 

 feet deep. 



Spring and well water is sometimes too cold to be 

 used for irrigation until it has been first warmed 

 in a reservoir, but this is not usually necessary ; and 

 since it contains far less plant food than stream 

 water, and is usually more difficult to secure, it 

 should not be used for irrigation when any other 

 can be had conveniently. Wells can be had in 

 most parts of the arid regions at a depth of 20 

 to 100 feet. The water is usually raised by a 

 windmill. Artesian wells those in which the 

 water comes up and overflows the surface of the 

 ground are sometimes available for irrigation, 

 notably in South Dakota. 



Use of Hydrant Water for Irrigation. The use 



