316 IRRIGATION PRACTICE 



to cultivate by the ridges. In other places the check 

 method of flooding is used. The whole orchard is sur- 

 rounded by ridges or checks, and water is allowed to flow 

 into the basin thus formed. This method is now seldom 

 used. The only flooding method of today, besides the 

 basin method, is the equivalent of the field ditch method, 

 whereby water taken from the head ditch by smaller 

 ditches, is led by small ditches, filled to overflowing, over 

 the whole orchard. 



The furrow method is the commonly adopted method 

 of all orchard irrigation. By this method a permanent 

 ditch is built at the head of the orchard. This may be a 

 flume or pipe made of wood or concrete. At various inter- 

 vals there are openings in the ditch or flume to lead the 

 water into the orchard; or if a pipe has been laid under- 

 ground, there are standpipes through which the water 

 pours out. From this head ditch the water is led by fur- 

 rows through the orchard. A head ditch carrying about 

 2 second-feet is about right for most orchard work. 



In the furrow irrigation of orchards it is very difficult 

 to admit to each furrow the same quantity of water. For 

 that reason small lath boxes, already described, are 

 employed to connect the head ditch with each furrow. 

 Instead of the lath boxes, small permanent pipes are 

 often placed at the head of the furrows. The length of 

 the furrows on sandy or gravelly soils should usually be 

 less than 500 feet, and on clayey, heavy soils, seldom 

 more than 600 feet. The shorter the furrow, within prac- 

 tical limits, the more probable is the equal distribution 

 of water at the head and end of the furrow. The grade of 

 furrows preferred in orchard irrigation is a fall of 3 to 4 

 inches to each 100 feet. If the land is steeper than this, 

 the furrows must be carried around the land in a zigzag 



