SOIL WATER 331 



Another way is to plow furrows eight to ten inches deep 

 in the direction of the surface slope and run the water into 

 these from the irrigation ditch. In either case the water 

 is allowed to soak in until the soil is thoroughly wet. The 

 surface is then cultivated so as to check surface evaporation. 

 It has been found that if the soil in certain irrigation regions 



IRRIGATION IN FURROWS 



does not have adequate under-drainage, it will become water- 

 logged. Injurious substances from the soil that should be 

 carried away by downward seepage and drainage are dis- 

 solved, carried to the surface, and left there by evaporation. 

 In such cases, artificial under-drainage has proved a neces- 

 sity. 



In the last few years the government and many private 



