Apr. I, 191S 



Capacities of Soils for Irrigation Water 



17 



tion exists, especially in the depths from 4 to 9 feet. Averages of the 

 moisture equivalents of plots D and F are used for this group, including 

 plots B to G, but the individual determinations are given in Table VI 

 to show the variation of texture which exists and for which due allow- 

 ance must be made. 



Table VI. — Moisture equivalents for soils at the University Farm, Davis, Cal., at depths 



varying from i to 12 feet 



[Results expressed in terms of percentage by weight and of acre-inches per acre-foot of soil] 



a The average value of the moisture equivalent as determined upon samples of soil from plots D and F 

 are used to represent the moisture equivalent in plots B, C, D, E. F. and G. 



The soil of plot H, classed by the Bureau of Soils of the United States 

 Department of Agriculture as a Yolo loam, is distinctly finer in texture 

 than that of the other plots, excepting a part of plot B. The differences 

 in texture between it and the other plots are most readily appreciated 

 by examination of the moisture equivalents of the two soils.* Averages 

 of the results of three years' observ^ations, representing the number of 

 inches and also the percentages of the quantities of water applied which 

 were retained by the upper 6 feet and the upper 12 feet of soil, are given 

 in Table VII.^ Assuming, upon the basis of the evaporation and trans- 

 piration experiments cited (6), that 0.7 inch of water was lost by evap- 

 oration and transpiration in the two days which elapsed between the 

 time of irrigation and of sampUng, plots B, C, and D retained in the 

 upper 6 feet of soil an average of about nine-tenths of the water applied. 

 Plots E, F, and G retained in the upper 6 feet nearly seven-tenths of 

 the water appHed, and the entire amount was apparently retained by the 

 upper 12 feet. Likewise, plot H retained two-thirds of the water applied 

 in the upper 6 feet of soil and nine-tenths in the upper 12 feet. 



1 Plot B, which lies nearest plot H. forms the division Une between the two types of soil above mentioned. 

 ' See {I, p. 10) for a discussion of Table \1I. 

 41811°— 18 2 



