FO-03875 Reviewed 1991
Soil water deficit is the amount of available water removed from the soil within the crop's active rooting depth. Likewise it is the amount of water required to refill the root zone to bring the current soil moisture conditions to field capacity. Soil water decreases as the crop uses water (evapotranspiration) and increases as precipitation (rainfall or irrigation) is added. Expressed in soil water deficit, evapotranspiration increases the deficit and precipitation decreases it. It is usually expressed in inches of water and can be estimated by several methods described later.
This material is based upon work supported by the U.S. Department of Agriculture, Extension Service, under special project number 89-EWQI-1-9180.
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