38 IRRIGATION PRACTICE 



it is probable that considerably more of the summer 

 precipitation would actually have been found if moisture 

 determinations had been made to greater depths. 



Similar results were obtained from the irrigation 

 experiments of the Utah Station. Water was added in 

 varying quantities to a deep loam soil already well filled 

 with water. The soil was sampled to a depth of 8 feet 

 twenty-four hours after irrigation. The results for one 

 year follow: 



Depth of water applied, in inches . . . 2.5 5.0 7.5 



Per cent of the water added, found one 



day after irrigation 100.00 77.04 68.87 



Some of the water was no doubt lost by evaporation; 

 some moved below the 8-foot limit, yet from 69 to 100 per 

 cent of the total quantity added was found to be stored 

 in the soil, for the use of plants, one day after irrigation. 



It is clear, therefore, that water, whether of rain or 

 irrigation, may be stored in soils. In clay soils, with fine 

 particles and a large surface, much more water may be 

 stored than in sandy soils, with coarse particles and a 

 small surface. If evaporation is prevented, and crops 

 are not growing on the soils, such stored water may 

 remain in the soil for long periods of time. If the water 

 is in the film condition, there is no great downward 

 movement after equilibrium is once restored. 



31. Absorption of water by soils. Water storage is 

 best accomplished when the water is made to enter the 

 soil quickly. This happens when the top soil is kept in a 

 loose condition and when the soil, to a depth of several 

 feet, is tolerably moist. If the surface is hard, the run- 

 off is large; if the soil is dry, the downward penetration 

 is slow. 



