Aug. 20. I9I7 Relation of Soil Water Movement 427 



varied from 3 to 10 times the coefficient. At the end of the five days 

 equilibrium had been practically attained in the finer-textured soils, but 

 in the coarser ones this was far from being the case. The coarser the 

 soil the more slowly was equilibrium reached. 



The rate of penetration showed little dependence upon the hygro- 

 scopicity, but was definitely affected by the moistness, the higher the ini- 

 tial moisture content of any soil within the limits employed the more 

 rapid being the downward movement of water. 



The distance of penetration during the five days following the applica- 

 tion of water increased with the initial moistness of the soil, but was not 

 closely related to the hygroscopicity, owing partly to the slowness with 

 which equilibrium is attained in the coarser soils. 



With the finer-textured soils the water content of the moistened layer 

 was not distinctly affected by the initial moistness, but with the coarser 

 members the drier the soil the v/etter was the moistened layer. 



Provided that a period of high evaporation is to precede the next rain, 

 the character of the weather immediately following a rain will have a 

 greater effect upon the loss of moisture by evaporation in the case of a 

 coarse than of a fine-textured soil. 



Glass tubes were filled with the same soils in the same three degrees of 

 moistness and the lower ends placed in contact wth water kept at a 

 constant level. The rate of rise during 8 or 10 days was observed and 

 the moisture in the uppermost layer of the moistened portion of the soil 

 column at the end of this period determined. 



At first the rise was most rapid in the soils of low hygroscopicity, but 

 the difference gradually lessened until those of intermediate hygro- 

 scopicity were in the lead. There was no definite dependence of the rise 

 upon the hygroscopicity. 



No definite dependence of the rate of rise upon the initial moistness 

 was shown, it being, in the case of the three moisture conditions studied, 

 generally most rapid in the moistest condition and slowest in the inter- 

 mediate. 



All the finer-textured soils showed the highest percentage of moisture 

 at the head of the advancing moist layer when used in the driest condi- 

 tion, but the coarser members showed no difference. The moisture con- 

 tent of this moist layer shows a rather constant relation to both the hygro- 

 scopic coefficient and the moisture equivalent, being similar to the 

 moisture retentiveness of the sam.e soils. 



The relative rates and distances of penetration in the different soils 

 are not similar to the relative rates and heights of capillary rise. 



LITERATURE CITED 

 (i) Alway, F. J., and Clark, V. L. 



I916. USE OP TWO INDIRECT METHODS FOR THE DETERMINATION OP THE HYGRO- 

 SCOPIC COEFFICIENTS OP SOILS. In Jour. Agr. Research, v. 7, no. 8, 

 P- 345-359' I fig- Literature cited, p. 359. 



