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Derived crop coefficients for winter wheat using different reference evpotranspiration estimates methods

Abstract : This paper reports the results of using three empirical methods (Makkink, Priestley-Taylor and Hargreaves) for estimating the reference evapotranspiration (ET0) in the semi-arid region of Tensift Al Haouz, Marrakech (center of Morocco). The Penman-Monteith equation, standardized by the Food and Agriculture Organization (FAO-PM), is used to evaluate the three empirical methods. The obtained ET0 data were used to estimate crop water requirement (ET) of winter wheat using the crop coefficient (K-c) approach and results were compared with ET measured by the Eddy Covariance technique. The result showed that using the original empirical coefficients a, alpha and C-m in Hargreaves, Priestley-Taylor and Makkink equations, respectively, the Hargreaves method agreed fairly well with FAO-PM method at the test site. Conversely, the Priestley-Taylor and Makkink methods underestimate the ET by about 20 and 18 %. After adjustment of the original values of two parameters alpha and C-m coefficients in Priestley-Taylor and Makkink equations, the underestimation of ET was reduced to 9% and 4% for the Priestley Taylor and Makkink methods, respectively, which led to an improvement of 55% and 76% of the obtained values compared with the original values.
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Submitted on : Tuesday, April 24, 2012 - 5:09:38 PM
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S. Er-Raki, A. Chehbouni, J. Ezzahar, S. Khabba, E. K. Lakhal, et al.. Derived crop coefficients for winter wheat using different reference evpotranspiration estimates methods. Journal of Agricultural Science and Technology, 2011, 13 (2), pp.209-221. ⟨ird-00668728⟩



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