IRRIGATION OF CEREALS 259 



series of Utah experiments it was found that 7^ inches 

 applied in one irrigation yielded nearly ninety-two bushels 

 of corn; whereas, the same quantity of water applied in 

 two equal irrigations yielded nearly 102 bushels of corn. 

 When the two irrigations were used, there was*a larger 

 proportion of seed in the whole plant, indicating that an 

 application of water was made possible at the time of 

 seed-formation, and nutritive materials were probably 

 transferred to the ears at the expense of the stover. An 

 annual precipitation of 12 to 15 niches coming largely in 

 the fall and spring would indicate that three irrigations 

 throughout the season should be sufficient to mature a 

 good crop of corn. True, many farmers apply water more 

 frequently than this, but the greater number of irrigations 

 is of doubtful value. Fewer irrigations, with many culti- 

 vations, would in the end be more satisfactory. When 

 four or five irrigations are applied, about 10 per cent of 

 the total water should be added in June; 50 per cent in 

 July; 30 to 40 per cent in August, and about 10 per cent in 

 September. When only two irrigations are applied, per- 

 haps 60 per cent of the total should come early in July. 



163. Quantity of water for corn. Corn is not a water- 

 loving crop. It will use large quantities of water if avail- 

 able, but it does not demand an abundance of water to 

 produce a good yield. As with other crops, the soil 

 determines chiefly the quantity of water used by the 

 corn crop. On shallow, gravelly and new soils, more water 

 is necessary than on the deep, clayey, well-tilled soils. 

 The climatic factors that increase evaporation increase 

 the water-use of the crop. 



Corn, like all other crops, is subject to the law that 

 the increase in yield is not proportional to the increasing 

 water supplied by irrigation. The more water is used, 



