Simulating Crop Evapotranspiration Using Insentek Soil Moisture for Maize Plants on Lysimeters

Crop evapotranspiration (ETc) simulation is important to modeling hydrological process in agro-ecosystem. In this study, ETc was monitored using a large-scale weighing lysimeter system, along with Insentek soil moisture probes at Xuchang Irrigation Experiment Station in 2015 and 2016. Relationships among daily ETc, leaf area index (LAI) and soil water content (SWC) were determined using the Levenberg–Marquardt Algorithm. Our results showed that ETc was significantly correlated with SWC in 0-40 cm soil layers, but not correlated with SWC below 40 cm soil layer. ETc was related to SWC in an exponential function combined with a quadratic function. Effects of SWC in 0-30 cm soil layers accounted for 32-53% variations of ETc. Averaging SWC across the 0-30 cm soil depth, it contributed 46% variations of ETc. Moreover, ETc was correlated with LAI in a negative linear manner, but its correlation coefficient is not significant (P>0.05). We concluded that SWC at top soil layer can be adopted to calibrate Insentek ETc simulation for maize plants.