Soil Water Content

Water in soil is a vital link in the hydrological cycle that controls exchange with the

atmosphere above and with the groundwater below. Water in soil acts both as a lubricant

and as a binding agent among the soil particulate materials, thereby influencing the structural

stability and strength of soil and geologic materials. The high heat capacity of water causes

a moderation of diurnal and seasonal temperature cycles at the soil surface. Chemically,

water serves as the transport agent for the dissolved inorganic chemicals and suspended

biological components that are involved in the processes of soil development and degrad-

ation. Biological production from soil, either as forest products or agricultural crops, is

influenced primarily by water availability. The measurement of soil water content then

is important directly for quantifying water balance, for estimates of plant water status, and

for characterizing most soil physical, chemical, and biological processes.