DRIVEN MACHINES 115 



Before buying irrigation machinery, it is a good 

 plan to test the water supply by temporary means. 

 Any good farm pump may be hitched to a gasoline en- 

 gine to determine if the water supply is lasting or not. 

 Permanent pumping machinery should deliver the wa- 

 ter on high ground. A main irrigation ditch may be 

 run across the upper end of the field. This ditch 

 should hold the water high enough so it may be tapped 

 at convenient places to run through the corrugations to 

 reach the roots of the plants to be benefited. There are 

 different systems of irrigation designed to fit different 

 soils. Corrugations are the cheapest and the most 

 satisfactory when soils are loose enough to permit the 

 water to soak into the soil sideways, as well as to sink 

 down. The water should penetrate the soil on both 

 sides of the corrugations for distances of several inches. 

 Corrugations should be straight and true and just far 

 enough apart so the irrigation water will soak across 

 and meet between. Some soils will wash or gully out 

 if the fall is too rapid. In such cases it may be neces- 

 sary to terrace the land by following the natural con- 

 tour around the ridges so the water may flow gently. 

 Where the fall is very slight, that is, where the ground 

 is so nearly level that it slopes away less than six inches 

 in a hundred feet, it becomes necessary. to prepare the 

 land by building checks and borders to confine the 

 water for a certain length of time. Then it is let out 

 into the next check. In the check and border system 

 the check bank on the lower side has an opening which 

 is closed during the soaking period with a canvas dam. 

 When the canvas is lifted the water flows through and 

 fills the next check. This system is more expensive, 

 and it requires more knowledge of irrigation to get it 



