Estimation of Paddy Rice Crop Coefficients for Penman-Monteith and FAO Modified Penman Method

Abstract

In 1998, Food and Agriculture Organization addressed that FAO Modified Penmanmethod possibly overestimates consumptive use of water comparing to the measured reference cropevapotranspiration (PET) and Penman-Monteith method can be better choice for accurate PETestimation. Nevertheless it is still difficult to find research efforts about paddy rice crop coefficient forPenman-Monteith method in South Korea. This study aims to estimate paddy rice crop coefficientsfor Penman-Monteith and FAO modified Penman methods in the manner of comparing twoequations. To estimate the crop coefficients, measured evapotranspiration data during 1982-1986and 1995-1997 were used. The average Penman-Monteith crop coefficients for transplanted paddyrice were ranged in 0.78 ~ 1.58, and the average FAO Modified Penman crop coefficients fortransplanted paddy rice were ranged in 0.65 ~ 1.35. This study also compared paddy rice cropcoefficients from the analysis with FAO irrigation and drainage paper No. 33 and 56.