220 SUCCESSFUL FARMING 



is applicable to the irrigation of alfalfa, grass and small grains. The 

 surface, however, should be divided into areas that may be covered in a 

 comparatively short time with the water available. When one area has 

 received sufficient water, the flow is then directed to the next one, and 

 so on until the irrigation is completed. If the field to be irrigated is 

 large, it necessitates a network of ditches or parallel ditches at intervals 

 of 300 to 400 feet, extending across the field. The distance to which the 

 water may travel over the surface of the ground depends on the char- 

 acter of soil and the ease of penetration. The more porous the soil, the 

 shorter the intervals should be. If the intervals are too long, the soil 



ORCHARD IRRIGATION BY FURROW METHOD. 1 



nearest the ditch becomes over-irrigated before the water reaches the 

 further portions. 



With this method of irrigation the water is generally made to flow 

 over the embankment by use of a temporary dam. The most convenient 

 form consists of a strong piece of canvas four or five feet square with one 

 edge securely nailed to a tough but light piece of wood that will reach from 

 bank to bank of the ditch. When this is laid in the ditch with the canvas 

 upstream and a- few shovels of dirt thrown on its edges, it completely 

 dams the water. It is easily moved from place to place as needed. 



All crops planted in rows, such as vegetables, sugar beets, potatoes 

 and fruit, are generally irrigated by the furrow method. Where the rows 

 are close together, the furrows alternate with the rows, being midway 



i Courtesy of The McGraw-Hill Book Company, N. Y. From " Use of Water in Irrigation," by Fortier. 



