SPRAY [RRIGATION. 



21 



Shobt-Post Type. 



If short posts are used they are set in the ground 2 1<> -i\ Beet and 

 cut off 1 to 3 feet above the surface. They are spaced is to 20 feel 

 apart and the nozzle line placed on top between nails or in roller 

 bearings. A 4 by 4 inch post srrves well for this type, but should be 

 treated as are tall posts. This construction is the least expensive, 

 but may cause a somewhat closer spacing of nozzle lines if a low 

 hydraulic pressure is to be used. This type also is somewhat in the 

 way of cultivation and is not efficient for tall-growing crops. When 

 nozzle lines are made portable on short posts, posts may be made of 



Pig. 13. — Overhead spray nozzle lines mounted on wooden posts 6ft feet above the. 

 ground. [Farm of Granville W. Leeds, Raneocas, N. J.] 



f-inch pipe sharpened and fastened to the nozzle line so that sup- 

 ports are moved with the pipe. 



High Posts and Cable-Suspexsion Type. 



Where high posts and cable suspension is used the posts are spaced 

 from 100 to 200 feet apart and the nozzle line suspended from a tight 

 cable or wire strand which takes the form of a catenary curve be- 

 tween posts (fig. 14). Telephone poles 8 to 10 inches at the base and 

 6 to 8 inches at the top can be used. A length of 2|-inch steel pipe 

 which may be filled with concrete makes a more substantial post. 



