IRRIGATION 109 



gation is the process of supplying dry lands with water 

 sufficient to meet the needs of the growing plants. 



Irrigation is practiced in certain sections of the West on 

 a large scale. Immense quantities of water are conveyed 

 directly to the farmer by ditches from distant sources, 

 lakes, rivers, or artesian wells, having suitable elevation. 

 Occasionally it is necessary first to pump the water into 

 large reservoirs to obtain a suitable supply and elevation. 

 Millions of dollars have been spent by the government and 

 by private individuals in installing irrigation plants ; and 

 thousands of acres which would otherwise be unproductive 

 are in this manner made to produce luxurious crops. 



Water gates regulate the flow of water from the reser- 

 voir into the main ditch, which carries it toward the plains 

 below. At proper distances, lateral ditches branch off on 

 either hand, and from these again new laterals, until the 

 land is intersected by a network of canals. Each ditch, 

 large or small, has its water gate, and some ditch reaches 

 each farm in the district. At a given farm, the water is 

 admitted from the public ditch to the farmer's private ditch 

 when needed ; and from this ditch it is conducted over the 

 land at will by shallow furrows to be taken into the soil. 



A similar system of irrigation is employed, on a much 

 smaller scale, in many ordinary farming districts by the 

 truck farmer. Truck plants are sensitive to drought, and 

 if the trucker must depend on the uncertain rainfall, his 

 profits will often disappear. Irrigation enables him to do 

 away with this uncertainty. 



In place of this ditch-and-furrow irrigation, some 

 truckers use an overhead system which supplies the water 

 in imitation of natural rain. Perforated pipes, an inch or 

 two in diameter, are erected on supports, high enough to 

 allow cultivation of the soil beneath them, and they are 

 so arranged over the field that by operating a lever one or 



