HORTICULTURE 113 



linear foot of flume depends on its size and the thickness of its sides 

 and bottom. 



For large head flumes and laterals, many fruit growers first 

 carefully prepare an earthen ditch which has carried water for at 

 least one season and afterwards line the inner surface with cement 

 concrete. 



Pipes and Standpipes. Head flumes, being placed on the sur- 

 face of the ground, interfere with the free passage of teams in cul- 

 tivating, irrigating, and harvesting the crop. Dead leaves from 

 shade and fruit trees also clog the small openings in the flumes. 

 These and other objections to flumes have induced many fruit grow- 

 ers of southern California to convey the water in underground pipes 

 and distribute it through standpipes placed at the heads of the rows 

 of trees. Both cement and clay pipes are used for this purpose. 



The former are usually molded in 2-foot lengths, with beveled 

 lap joints, and consist of a 1 to 3 or 1 to 4 mixture of cement and fine 

 gravel and sand. The most common sizes are 6, 8, 10, and 12 inches 

 in diameter, having a thickness of shell in the 12-inch pipe of 1% 

 inches which is reduced to a trifle more than 1 inch in the 6-inch 

 pipe. Piping of this kind, when well made and carefully laid, will 

 withstand a head of 10 to 16 feet. The clay pipe is similar to that 

 used in cities for sewers and having stronger joints, withstands a 

 greater pressure but costs more. 



A line of pipe is laid about 2 feet below the surface from the 

 feed main and measuring box across the top of the orchard, and as 

 each row of trees is passed a standpipe is inserted. Various devices 

 are employed to convey the water from the pipe to the surface of the 

 ground at the head of each tree row and divide it up evenly among 4 

 to 6 furrows. One of the most common consists of a series of stand- 

 pipes, the top of each set rising to the same elevation. At each 

 change of elevation special standpipes are used and in these are in- 

 serted gates provided with overflows. 



Occasionally a high-pressure pipe is substituted for cement and 

 clay. This is tapped at the head and in line with each row of trees, 

 and a small galvanized-iron pipe is inserted. These standpipes are 

 capped by an ordinary valve which regulates the flow to each row 

 of trees. 



Making Furrows. The length of the furrow is often governed 

 by the size of the orchard. The rows of citrus trees seldom exceed 40 

 rods in length, but the apple orchards of the Northwest are larger as 

 a rule. Even in large tracts it is doubtful if it ever pays to run water 

 in furrows more than about 600 feet. Where the soil is open and 

 water sinks readily through it, short furrows should be used, other- 

 wise much water is lost in deep percolation on the upper part of the 

 tract. An authority of San Diego County, Cal., after a careful inves- 

 tigation of this subject has reached the conclusion that on sandy or 

 gravelly soil having a steep slope the proper length of furrows is 

 200 feet, while on heavier soils and flatter slopes the length may be 

 increased to 600 feet. 



The grade of furrows varies quite widely. In flat valleys it is 



