DISTRIBUTION OF MOISTURE IN SOIL COLUMNS. 3 
horizontal. The percentage of moisture in such a case will decrease 
somewhat irregularly with distance from the source of water. If this 
inclined stratum encounters an impervious stratum so as to retard 
or stop entirely the capillary movement of moisture downward, the 
moisture will then accumulate and ultimately cause saturation. 
This saturated area will in time extend back up to near the original 
source of moisture. In alluvial soils such conditions are often found 
and water-logging may result in this way. 
The capillary distribution of moisture in the presence of a water 
table is of far more importance in irrigation and drainage than is 
usually recognized. 
RESULTS OF PREVIOUS EXPERIMENTS. 
It has been mentioned that the results of some of the experiments 
at Riverside indicated an uneven distribution of moisture throughout 
the vertical soil columns. The 
first two determinations made * 
for the distribution of moisture 
in vertical soil columns at 
Riverside were for Riverside 
and Whittier soils. These col- 
umns were respectively 7 by 7 
inches and 8 Ay 8 inches in 
cross section. 
The moisture in these col- 
umns was determined at vari- Me Se 
ous heights throughout the col- Fie. 1.—Distribution Bi rar alee, in large vertical 
umns, the samples being taken 
with a soil auger. The percentages of moisture found at various 
heights above the water are plotted in Figure 1. 
& 
w 
o 
e of Moisture 
wt 
Percenta 
i) 
20 30 
Inches Above Water 
EXPERIMENTS WITH SOIL COLUMNS OF SMALL CROSS SECTIONS. 
In taking samples with a soil auger from soil that is near capillary 
saturation one can never be certain that an accurate sample is ob- 
tained. For this reason the results from these two large columns 
were not relied upon as correctly representing the moisture conditions 
that existed. They indicated, however, that the distribution of 
moisture in vertical soil columns might not be uniform as was com- 
monly supposed. 
Table 1 gives the results of moisture determinations for these two 
columns. The percentages of moisture are calculated upon a dry- 
soil basis. The first column gives the distance above the surface of 
the water at which the samples were taken. Opposite these distances 
are found the corresponding percentages of moisture for the two soils. 
