DISTRIBUTION OF MOISTURE IN SOIL COLUMNS. 7A | 
the soil is deep. Hilgard in “Soils” (1916), and Widsoe and Mc- 
Laughlin in Bulletin 115 of the Utah Experiment Station report 
finding under field conditions a distribution of moisture somewhat 
similar to the distribution shown in the last two tubes. 
In considering tubes Nos. 22 and 23 it must be kept in mind that 
in tube No. 22 the “‘lift’’ was 9 inches, while in tube No. 23 it was but 
4inches. In the former tube the moisture was furnished in compara- 
tively meager quantities to the upper end of the inclined part of the 
soil column and in tube No. 23 rather copiously The former tube 
contained comparatively light pervious soil. The distribution of 
moisture in these two tubes was quite similar. 
Sample X (see Table 8) shows the percentage of moisture found in 
that part of the soil column contained in the “lift,’’ which is between 
the surface of the water in the tank and the point where the soil col- 
umn changes direction. This sample in all cases was taken 2 inches 
below the apex of the tube. It is significant that the inclined part of 
the column can dispose of more moisture than can be furnished by 
the vertical part of the tube. That gravity in conjunction with cap- 
illarity would cause such a difference in moisture distribution within 
2 or 3 inches is somewhat surprising. Had samples been taken on 
each side of the apex of the tubes and nearer to the apex there is no 
doubt that this same difference in moisture would have been shown 
within a much shorter distance. 
SUMMARY. 
The moisture, as found in these experiments, was not distributed 
at a uniformly decreasing rate with height above the water. 
The maximum percentage of moisture was found, not immediately 
above the water surface, but at an appreciable distance above it. 
The line plotted to represent the percentage of moisture found in 
the column is an irregular curve, with the end representing the upper. 
end of the column approaching a straight line. Insome of the experi- 
ments the second fourth of the column, from the bottom, contained 
as much or nearly as much moisture as the bottom fourth of the 
column. 
In all tests except those in which Idaho sandy soil was used, ex- 
tending over a period of 10 days or longer, the lower half of the tube 
contained at all points more moisture than the average amount 
contained throughout the column. 
The point at which the average percentage of moisture was found 
varied from the middle to two-thirds the height of the column. 
The height at which the maximum percentage of moisture was 
found varied from one-seventh to one-fourth the height of the moist 
part of the soil column. 
In all columns there was a considerable length, a few inches above 
the water, containing approximately the same percentage of moisture. 
The various methods of packing the soil columns tried in these 
experiments did not appear to alter the general plan of moisture 
distribution. , 
The facility with which air may escape from or enter into the soil 
column does not alter the general plan of the moisture distribution. 
The ventilated soil columns had a slightly more uniformly varying 
moisture content with height above water than the columns not 
ventilated. 
