TIME OF IRRIGATION 181 



spring, there may be an abundance of water, heavily 

 charged with the valuable constituents of the soil, for 

 the use of the young plant. 



113. Early spring irrigation. This refers to irriga- 

 tion made soon after the winter breaks, either before or 

 after planting, but nearly always before the plant is really 

 in need of additional water. When spring appears, the 

 melting mountain snows increase greatly the river flow, 

 culminating in the period of high water and spring floods. 

 Unless reservoir provisions are made these great quan- 

 tities of water flow away unused and it is an increasingly 

 important question whether this spring flow may be 

 diverted profitably upon cultivated lands. 



If the soil has been well -filled with water during fall 

 and winter, either by late irrigation or by heavy winter 

 precipitation, it is probably useless to expect that spring 

 irrigations will benefit crops. The early application of 

 water may rather be detrimental in such places, as it 

 tends to wash down, beyond the reach of plant roots, the 

 rich soil solution formed during the winter. 



On the other hand, wherever the winters are dry, or 

 where fall and winter irrigation cannot well be practised, 

 the application of water in the early spring may be bene- 

 ficial in stimulating early crop-growth. In fact, in local- 

 ities where the soil in spring is in a condition too dry 

 for germination, it is indispensable that water be applied 

 to the soil about the time of planting, if any crop at all 

 is to be obtained. In such districts, water is often applied 

 to the soil some time before the planting season. After 

 the water has distributed itself throughout the soil, the 

 top soil is loosened to prevent evaporation and to furnish 

 a good seed-bed. Usually, however, the seed is sown in 

 the relatively dry soil and a rather heavy irrigation is 



