Simulating Maize Production, Water and Surface Energy Balance, Canopy Temperature, and Water Stress under Full and Deficit Irrigation

Abstract

Abstract. Surface energy balance is critical to the understanding of crop evapotranspiration (ET) requirements and crop water stresses. The objective of this study was to evaluate the simulation of crop growth, water and surface energy balance components, canopy temperature, and water stress under fully irrigated and deficit-irrigated corn in eastern Colorado using a hybrid version of the Root Zone Water Quality Model (RZWQM) and the Simultaneous Heat and Water model (SHAW) (RZ-SHAW). The field experiment was conducted in 2010 under both full and deficit irrigation conditions with energy balance measured using the Bowen ratio method. The model simulated grain yield satisfactorily, with an error of less than 5%. Leaf area index, daily ET, soil water content, canopy temperature, and energy balance components, including net radiation (R n ), latent heat (LE), sensible heat (H), and ground heat flux (G), were simulated well, with coefficients of determination (R 2 ) ≥ 0.64 and model efficiencies (ME) ≥ 0.57 for both full and deficit irrigation fields. The RZ-SHAW model accurately predicted the responses of crop growth and ET to water stress, and the simulated water stress was in good agreement with measured elevated canopy temperature with deficit irrigation after silking. However, the model performance was not acceptable in predicting plant height for water-stressed corn, and the simulated increase in canopy temperature under deficit irrigation was about 30% of the observed temperature increase. This study suggests that while the RZ-SHAW model can be used to evaluate the response of corn yield and water and energy balances to water stress, the simulation of the effects of water deficit on plant height and canopy temperature need further improvement.