FO-03875 Reviewed 1991
Crop water use is the amount of soil water released to the atmosphere from soil surface evaporation and plant leaf transpiration. This is also called evapotranspiration or ET. It is usually expressed in inches per day or per season. Weather and crop development affect daily crop water use throughout the growing season. Figure 3 shows a typical daily water use pattern for corn in central Minnesota.
Figure 3. A Typical Crop Water Use Pattern for Corn in Central Minnesota.
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Yield of most crops is directly related to seasonal ET and especially transpiration. If plant transpiration is limited, yield usually decreases proportionally. Transpiration may decrease whenever the soil water deficit exceeds the recommended allowable soil water depletion limits. Daily crop water use can be estimated by several methods such as the evaporation pan, Jensen-Haise ET model, or temperature-based ET tables. Each of these methods is discussed 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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