Estimating Deep Drainage Between Irrigations1
- D. E. Miller and
- J. S. Aarstad2
This paper treats the situation, common in irrigation, in which the water table is deep enough to be ignored and applied water moves downward by drainage and is taken up by plants. When plants are transpiring, soil water content is reduced by both deep drainage and plant extraction. Drainage rates from a wetted depth of soil are related to the total water contained in that depth when there is no plant use. This same relation can be used to estimate drainage following an irrigation when the soil is cropped. However, in a series of irrigations, there is a delay between the end of irrigation and the beginning of drainage, and drainage is overestimated. If reduced irrigation efficiencies can be tolerated, overirrigation can lengthen time between irrigations, especially if evapotranspiration rates are low.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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