82 Strawberry-Groioing 



Furrow system. 



Surface or gravity irrigation by means of furrows is 

 the cheapest method when feasible. Surface irrigation 

 requires that the land be brought to a uniform grade 

 and all hollows filled. In arid regions the subsoil usually 

 is like the surface soil and no harm is done by grading. 

 In humid regions the subsoil usually is quite different 

 from and frequently inferior to the surface soil. Grading 

 may seriously injure the field, temporarily at least. 

 Land with a uniform, gentle slope is essential for furrow 

 irrigation in a humid region. 



Overhead pipe, pressure or sprinkling system. 



The overhead pipe system of irrigation finds favor 

 among market-gardeners. The water is applied from 

 pipes, under a pressure of fifteen to forty pounds. Usually 

 it is pumped directly into the system, not to a reservoir. 

 The mains are laid in the ground 300 to 400 feet apart. 

 They should be smaller at the end of the line than at the 

 beginning, so as to maintain a uniform pressure. Smaller 

 laterals, 150 to 200 feet long, are run from these, spaced 

 forty to fifty feet apart. The laterals are carried on posts 

 seven to eight feet high, so as to permit horse tillage 

 beneath (Plate VI). 



The laterals may be level, but a slight fall is preferable. 

 They are fitted with small brass nozzles, placed three 

 to four feet apart in a straight line. These throw a spray 

 twenty to thirty feet. The laterals are attached to the 

 main with an adjustable union, which permits them to 

 be rotated so as to direct the spray first on one side, then 

 on the other, thus covering a strip forty to fifty feet wide. 

 The turning can be done by hand, or with a hydraulic 

 oscillator. This connection also permits the spray to be 



