IRRIGATION 



259 



sufficient water has been admitted to any one furrow. It 

 is also customary in some localities to lay underground pipes 

 with standpipes coming to the surface at the distributing 

 points. The standpipe may discharge directly into the 

 furrow or check or the water may be carried a short distance 

 through a hose. These methods of bringing in the water 

 supply are more expensive in first cost, but they frequently 

 save expense in the work of distributing water and, since 

 they prevent waste, make it possible to irrigate a greater 

 area with a given quantity of water. 



Subsurface irrigation. Subsurface irrigation is a system 

 in which pipes are laid underground at the places where the 

 water is needed. The supply of water is turned into these 

 pipes and escapes at the joints or through special openings, 

 the water passing out laterally into the soil by absorption. 

 This method is very satisfactory from the standpoint of 

 cultivation and convenience in applying the water, but it 

 is only under special conditions of soil that it distributes 



After Irrigation Investigations, U. S. Dept. Agri. 



Fig. 216. Irrigating strawberries by rectangular flume 



the water in a satisfactory manner. In an open soil the 

 action of gravity tends to pull the water downward and 

 there is great waste. In soils with an impervious stratum 



