Actual Evapotranspiration for Sugarcane Based on Bowen Ratio-Energy Balance and Soil Water Balance Models with Optimized Crop Coefficients

Abstract

Evapotranspiration is an important parameter to evaluate soil water deficit and water use efficiency, especially at places with irregularly distributed precipitation. The aim of this study was to assess the daily actual evapotranspiration (ETa) estimated by the Thornthwaite and Mather soil water balance method adapted for crops (ThM) and by the dual Kc approach with the crop coefficients optimized from inversing modeling and by the adjustment procedure suggested in FAO-56. The models comparison and optimization were performed with actual evapotranspiration determined by the Bowen ratio -energy balance method (ETβ) for sugarcane at full canopy closure grown in Alagoas State, Northeastern Brazil. The objective function of the inverse problem was defined in terms of ETβ and ETa estimated by the ThM and dual Kc method by optimizing single crop coefficient (Kc) and the basal coefficient Kcb, respectively. Both optimized Kc and Kcb were lower than the adjusted Kc FAO56, with optimized Kc only 3% less than the Kc obtained experimentally. ETa estimated by ThM and dual Kc models with optimized crop coefficients (Kc = 1.05 or Kcb = 1.00) had similar high precision (r² > 0.79) and accuracy (dm > 0.93 and RMSE < 0.30 mm d -1 ), whereas using the coefficients derived from FAO 56 overestimated ETa in both models.

Interannual dynamics and controlling factors of the ratio of actual to potential evapotranspiration across typical ecosystems within the Heihe River Basin

“…Several methods have been utilized for this purpose. The water balance method (Harrison et al, 1993; Jarvis & McNaughton, 1986), lysimeter method (Davis et al, 2012), Bowen ratio‐energy balance method (da Costa Faria Martins et al, 2022; Zhang et al, 2008), and eddy covariance method (Baldocchi, 2003) are commonly used in this regard. Additionally, the isotopic tracer method has been employed to partition AET into transpiration (AT) and soil evaporation (AE) (Wen et al, 2016).…”

Effects of plant spacing on evapotranspiration for estimating crop coefficient of Japonica rice

“…Experimental data from across Asia indicate that, on average, about 2,500 litres of water need to be supplied (by rainfall and/or irrigation) to a rice field to produce 1 kg of paddy rice [40,43] but this can vary depending on various factors such as crop management, weather conditions, and soil properties. To ensure sustainable production of rice, accurate estimation of crop evapotranspiration ET is important for irrigation planning and scheduling [1,2,3,4,13,53,54]. Researchers have focused on improving the accuracy of various methods for estimating evapotranspiration over the last century.…”