Investigations made at the Utah Station have shown
that undisturbed soils within the Great Basin frequently contain, to
a depth of 10 feet, an amount of water equivalent to 2 or 3 years of
the rainfall which normally occurs in that locality. These
quantities of water could not be found in such soils, unless, under
arid conditions, water has the power to move downward to
considerably greater depths than is usually believed by dry-farmers.
In a series of irrigation experiments conducted at the Utah Station
it was demonstrated that on a loam soil, within a few hours after an
irrigation, some of the water applied had reached the eighth foot,
or at least had increased the percentage of water in the eighth
foot. In soil that was already well filled with water, the addition
of water was felt distinctly to the full depth of 8 feet. Moreover,
it was observed in these experiments that even very small rains
caused moisture changes to considerable depths a few hours after the
rain was over. For instance, 0.14 of an inch of rainfall was felt to
a depth of 2 feet within 3 hours; 0.93 of an inch was felt to a
depth of 3 feet within the same period.
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