Performance Assessment of the Fao Aquacrop Model for Maize Yield, Biomass and Water Productivity Along the River Nile, Egypt

Abstract

Different three maize field experiments represent the main agro ecological zones (Sakha, Giza and Qena), including full and deficit irrigation, were conducted in Egypt along the river Nile. The last updated version of AquaCrop model was evaluated with maize yield and water productivity under different irrigation water treatments (1.2, 1, 0.8 and 0.6 from actual evapotranspiration ET c ). The model was evaluated after parameterization using field observations relative to canopy cover (CC), total biomass and yield data as well as using conservative parameters. The treatments show highly agreement between measured and simulated values of CC except the highest severe irrigation treatment (I4). The determination coefficients are higher (R 2 >60), thus indicating that the CC model explains significantly the variance of observed CC values. Also, estimated errors are then small, with RMSE ranging between (0.3 to 13%), and d varying between 0.6 and 0.98. Also, the agreement between simulated and observed maize grain yield, final biomass and water productivity were good with R 2 , RMSE and d. Results cleared that the model is considered a good decision support tool for exploring irrigation management and maize production in Egypt. Nevertheless, the model showed slightly uncertainty specially under sever deficit irrigation. It is supposed that, AquaCrop would be useful if it included some calibrated parameters about root distribution system in soil, because it is a water driven model and relies mainly on soil water balance and uptake.

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“…A similar match between the observed and AquaCrop‐simulated yield and total biomass was reported in the other studies (e.g., nRMSE = 6%–12% and 6%–8% for rice yield and total, biomass, respectively, reported by Vahdati et al. ( 2020 ); NSE = 85%–98% and 80%–85% for maize yield and total biomass, respectively, reported by Kheir and Hassan ( 2016 ); nRMSE = 10.9%–13.9% and NSE = 96% for wheat yield, reported by Alvar‐Beltran et al. ( 2021 ); and nRMSE = 8.1% for barley yield, reported by Yawson and AduArmah ( 2020 )).”…”

“…A close match was obtained between the observed and simulated crop yield and total biomass during the validation process, with nRMSE, nMBE, and NSE, respectively, ranging from 5.4% to 6.9%, (−1.4%)-(−2.7%), and 91.8%-98.3% for crop's yield; and ranging from 5.1% to 6%, (−1.6%)-(−2.6%), and 95%-96.3% for total biomass. A similar match between the observed and AquaCrop-simulated yield and total biomass was reported in the other studies (e.g., nRMSE = 6%-12% and 6%-8% for rice yield and total, biomass, respectively, reported by Vahdati et al (2020); NSE = 85%-98% and 80%-85% for maize yield and total biomass, respectively, reported by Kheir and Hassan (2016); nRMSE = 10.9%-13.9% and NSE = 96% for wheat yield, reported by Alvar-Beltran et al (2021); and nRMSE = 8.1% for barley yield, reported by Yawson and AduArmah (2020)). "…”