IltKIGATION OF FIELD CROPS. 155 



after the first irrigation the crop may need water again, 

 if there have been no rains in the interim, but this mat- 

 ter can be determined by an examination of the soil. 

 The second irrigation will require not more than half 

 the water given in the first application. It is a great 

 advantage to keep the plants growing steadily during 

 the early period of growth. 



Some irrigators are in favor of giving a third wet- 

 ting not a very heavy one, however just as the grain 

 is heading, claiming that this practice makes larger ber- 

 ries and a grain yield of more specific gravity. Over- 

 watering at this time may cause rust, and great discretion 

 must bo used as to the water at this period. If the 

 ground is moist it is not necessary to give the heading 

 irrigation. Figure 55 shows the process of flooding a 

 wheat crop from a field furrow, the irrigator throwing 

 in a diverting check of earth to flood the field laterally. 



If the first irrigation is late and there is a good deep 

 compact subsoil, one irrigation will usually make a crop, 

 and we would rather have one twelve-inch irrigation 

 than two six-inch ones. The surface can be covered 

 with six inches if the incline is steep, and on such a sur- 

 face it is best to irrigate light and often, as by r mining 

 heavy heads for a considerable time the plants maybe 

 washed out. On the upper bench lands of the West, 

 when fairly level, two irrigations are all that is needed, 

 and with only one after three years of cultivation there 

 is no danger of a complete failure of the crop. 



Professor Blount, who is the best authority in the 

 world on wheat growing by irrigation, advocates the 

 cultivation of wheat by the ridge system. He says : 

 "Wheat in ridges with furrows between will pay many 

 times over all the extra cultivation and expense. The 

 ridges should be twenty inches apart, running north and 

 south, so that the sun may get in upon the roots during 

 the later growth. On these ridges, which are two and 



