Lawn wal planted in three lysimeters, and cotton was planted in two lysimeters in order to evaluate its crop coefficients ii Isfahan. The evapotranspiration of lawn and cotton were measured for two years on daily basis . The crop coefficient of cotton for the growing season, monthly crop coefficients, and crop coefficients for 10 days intervals were calculated using evapotranspiration of lawn as the potential evapotranspiration and evapotranspiration of cotton as the actual evapotranspiration. The seasonal crop coefficient of cotton was computed 0.71 in Isfahan. The maximum crop coefficient is 1.02 , and occurs 100 days after planting and 10 days after effective cover.
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