Mar. i, 1924 
Movement of Water in Irrigated Soils 
623 
free water, which is to say that the removal of 1 acre-foot of water 
changed 7.7 acre-feet of subsoil from a saturated to an unsaturated 
condition. In other words, the removal of 1.56 acre-inches of water 
lowered the water table 1 acre-foot. It is probably safe to assume that 
under the conditions of this experiment there was some inflow of water 
from the surrounding saturated subsoil that was not observed, so that 
the ratio 1.56 acre-inches per acre-foot is probably too high rather than 
too low. 
F. H. King (12, p, 132-134) has reported on the water content of 
undisturbed field soils when saturated and when only the bottom inch of 
each 1-foot section was saturated. From his figures for soil from the 
third, fourth, and fifth foot sections, there was an average difference of 
0.4 of an inch less water in the soil when the bottom only was saturated 
than when the whole of the section was saturated. In another experiment 
King set up columns of soil 7 feet long which were first saturated and 
then allowed to stand for 60 days with the bottom of the soil column 
in water and the top protected from evaporation. The columns were 
then cut into 6-inch sections and the water content of each section was 
determined. 
In the results reported by King for this experiment, if the top and 
bottom 6-inch sections be eliminated, it is found that the water content 
decreases fairly consistently from the lower to the upper sections. Where 
the soil used was classed as sandy loam the decrease in water content of 
each 6-inch section from below upward was at the rate of 0.6 per cent. 
With the soil classed as clay loam the rate of decrease was slightly less 
than 0.5 per cent per section. 
These figures when converted into inches of water for each i-foot 
layer of soil give an average decrease of water of slightly more than 0.1 of 
an inch for the sandy loam and slightly less than 0.08 of an inch for the 
clay loam. 
It would appear from such evidence as is available that when con¬ 
sidering only the layer of subsoil immediately above the level of under¬ 
ground water, the addition of o. 1 of an inch of water would result in raising 
the ground-water level 1 foot. As a matter of fact, it would not be correct 
to conclude that the removal of a volume of water equal to o. 1 of an inch 
in depth would lower the underground water level as much as 1 foot or 
that the addition of that quantity would raise it 1 foot for the reason that 
any change in water level would affect the moisture conditions for some 
distance above the water line. 
The extent of the change of moisture conditions of the subsoil conse¬ 
quent upon or necessary to produce a change of 1 foot in the ground-water 
level would be influenced materially by the texture and density of the soil 
material. It is probable that in some situations the addition or removal 
of half an inch of water might raise or lower the ground-water level 1 foot 
while in other situations it might require 1X inches to cause the same 
change. Speaking generally, it may be assumed that the addition or 
removal of 1 inch of water may raise or lower the ground-water level 
1 foot. 
