IREIGATIOl^ IN NORTHERN COLORADO. 



53 



equipped with concrete or wooden turnouts to supply the j&eld laterals. 

 For alfalfa the field laterals are permanent, but for annual crops 

 they are made each spring with a ditching plow, and after irrigation 

 is completed they are plowed flat again so that harvesting machinery 





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Fig. 5. — Irrigation of alfalfa. Water requirements of 988 acres in 1916 and 

 of 686 acres in 1917. 



may pass over them without difficulty. If the field to be irrigated is 

 smooth and has a uniform slope, the field laterals are made parallel, 

 75 to 200 feet apart, and oblique to the main slope of the land. In 

 this case the water from one lateral irrigates the field down to the 



