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SOIL PHYSICS AND MANAGEMENT 



Methods of Irrigation. The manner of applying water to 

 soils determines to a large extent the influence it has both upon 

 the plant and soil as well as the effectiveness of the water itself. 



In arid regions two general systems of irrigation are followed, 

 flooding and furrowing, each of which has its advantages under 

 certain conditions. The determining factors are (1) the character 

 of the soil, (2) the amount of water per -unit of time or "head/ 2 

 (3) the contour or lay of the land, and (4) the kind of crop. 



(a) Flooding. A common method for applying water is by 



Fro. 122. Basin or check system of irrigating orchards. Principles of Irrigation Practice, 

 Widtsoe. (Courtesy Macmillan Company.) 



flooding the entire area. This requires that the land shall be prac- 

 tically flat and the soil one that does not erode badly nor bake 

 upon drying. Heavy soils are best adapted to this method, so that 

 when the large volume of water is turned on the soil will not wash. 

 If the volume of water is too small it will sink into the soil before it 

 reaches the other side of the field. Alfalfa, pasture and meadow 

 land and wheat and other small grains may be successfully irrigated 

 in this way. Three principal modifications of this method are 

 flooding closed fields, flooding open fields and basin flooding. The 

 closed-field flooding or check flooding, as it is sometimes called, is 



