Performance assessment of the DSSAT-CERES-Wheat model under different irrigation strategies in the semi-arid region of Marrakesh

Water scarcity is a major problem in the arid and semi-arid areas of Morocco, where irrigation is essential for agriculture. Crop growth models can enhance water use efficiency, thus providing an economic benefit while reducing pressure on water resources. In this study, we evaluated the modeling performance of the DSSAT-CERES-Wheat model in estimating Evapotranspiration (ETa), Total soil water (TSW), Grain yield, Tops weight and phenological stages of winter wheat in the semi-arid region of Tensift Al Haouz, Marrakech. The simulation was performed at a daily time step during two successive growing seasons 2002/2003 and 2003/2004. The model calibration was done firstly on two fields and ETa, TSW phenological stages, and productive variables were calibrated after the comparison of the simulated and observed data. Afterward, the validation was performed on four fields during the two growing seasons. The results showed that the model simulates reasonably good Grain yield, Tops weight and phenological stages. Moreover, The average values of  RMSE  between observed and measured ETa, TSW, Grain yield and Tops weight were respectively, 0.70mm/day, 25mm, 0.6 t/ha and 2 t/ha for the validation fields. Statistical parameters like R2, d, and NRMSE were additionally used and showed that the model simulates acceptably the above-mentioned parameters. Furthermore, The Penman-Monteith FAO56 and Priestley and Taylor Evapotranspiration simulation methods were compared, the average values of d  and R2 were respectively 0.85, 0.70 for the Penman-Monteith method, and 0.80, 0.65 for the Priestley and Taylor method. Thus, the DSSAT model can be considered a useful tool for monitoring the management of wheat in arid and semi-arid regions.

Keywords: DSSAT, wheat, irrigation, water scarcity, crop model