Evaluation of Evapotranspiration in Different Paddy Soils Using Weighable Lysimeter Before Flooding Stage

Water is closely linked to agricultural productivity and is an essential resource for agriculture.Climate change and drought are causing water scarcity, and that has an enormous impact on agricultural productivity.Efficient water management methods are needed to prepare for water shortages.The lysimeter is well known as a facility for precisely measuring water and nutrient movement in the soil.Therefore, this study was conducted to investigate the evapotranspiration of different paddy soils using weighable lysimeter and to evaluate the relationship between the evapotranspiration estimated by weighable lysimeter and the reference evapotranspiration estimated by FAO Penman-Monteith equation and Hargreaves equation.This study was performed in lysimeter facility located at the National Institute of Agricultural Sciences, Rural Development Administration, and used lysimeter weight values and meteorological data measured from 1st January to 30th April in 2018.The daily evapotranspiration estimated by the lysimeter was ET LY , the reference evapotranspiration estimated by FAO Penman-Monteith equation was ET PM , and the reference evapotranspiration estimated by Hargreaves equation was ET HS .ET LY showed that loam (L) was higher than that of sandy loam (SL) and silty clay loam (SiCL).The accumulated evapotranspiration from 1st January to 30th April in 2018 was in the order of L (235 mm) > SL (231 mm) > SiCL (192 mm).Solar radiation showed a higher coefficient of determination (R 2 ) than mean temperature in the correlation between the meteorological data and ET LY .The relationship between ET LY and ET HS showed a relatively low coefficient of determination, whereas the coefficient of determination in the relationship between ET LY and ET PM showed relatively high fitness for SiCL (0.631), L (0.860) and SL (0.884).Precise measurement and management of soil moisture using lysimeter are expected to be possible.