182 IRRIGATION PRACTICE 



applied afterward. In either case, germination is 

 encouraged. 



Our present knowledge leads to the belief that spring 

 irrigation should be practised only where it is absolutely 

 indispensable. The value of early irrigation depends 

 upon the quantity of water in the soil in the early spring. 

 It is much better, wherever conditions permit, to irrigate 

 in the fall, and to conserve in the soil as much as possible 

 of the natural precipitation, so that the seed may be 

 planted without irrigation and the first irrigation may be 

 postponed until early growth is well started, and late 

 spring or early summer weather has set in. 



This matter was tried out at the Utah Station with the 

 result that the longer the spring irrigation was postponed, 

 the more valuable it became in increasing the crop-yield. 

 Under the prevailing conditions, there was a liberal 

 fall, winter and early spring precipitation, so that at plant- 

 ing time the soils were usually saturated with water. To 

 irrigate such soils does little good, and possibly results 

 in harm. Only where germination will be delayed or be 

 incomplete without irrigation should the early applica- 

 tion of water be practised. It is of prime importance, for 

 obtaining the best results, that the soil be well filled with 

 moisture at the time of planting. 



114. Irrigation during growth. The time to irrigate 

 crops during their growth should measurably determine 

 the rotation of water from irrigation systems and it bears, 

 therefore, directly upon the question of canal manage- 

 ment. 



In the spring, when the root-system is being developed, 

 the growth above ground is slow. With each day, however, 

 the rate of growth increases, until buds and flowers 

 appear. At that time the rate of plant-growth is most 



