Pipe Line Structures 



145 



In clay soil it is easy to keep the four streams separate, but in 

 sandy soil the streams are apt to run together. Usually 12-inch 

 pipe is used tor four side openings, and 16-inch pipe or pipe hoods 

 for six openings. For easily eroded soil, the 16-inch hoods are 

 advisable for four openings. 



Risers and hydrants of various designs are used for alfalfa, but 

 it is believed that a simple riser and valve terminating 2 inches 





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Fig 30.— Method of irrigation from pipe line at Continental, used on the bottom- 

 land where the general slope is about 20 feet per mile. 



below the ground level is preferable to the more expensive systems. 

 The long lines of 6-inch light galvanized iron pipe with taper joints, 

 called "surface pipe," are a source of much labor, expense, and leak- 

 age, and their use should be discouraged. Surface pipe of canvas is 

 sometimes employed, but it is most unsatisfactory. 



