AquaCrop model evaluation to estimate of Maize yield and soil salinity under different agriculture managements and irrigation with saline water

Recently, FAO has proposed the version 4 of AquaCrop model that can simulate the effect of irrigation with saline water on yields and soil salinity. In this study, the AquaCrop model was evaluated under different agriculture managements and irrigation with saline water for Maize (SC.704). Field experiments of this study were done in the agriculture farm of Shahid Chamran University. Different crop managements included without crop residues, use of crop residues on soil surface as mulch and mix of crop residues with surface soil layer to 30 cm depth and water irrigation salinity at three level included water salinity of Karoun river ( On average 2ds/m), 4.5 and 7 ds/m. After model calibration to offset some input parameters, model validation was performed. The amount of determination coefficient (R2), relative error (RE), coefficient of residual mass (CRM) and Normalize root mean square error (NRMSE) in validation for soil salinity were respectively 0.83, 10.6%, 0.04 and 11.64, for yield were respectively 0.93, 5.2%, 0.01 and 5.58, for biomass were respectively 0.99, 4.2%, -0.02 and 4.48 and for canopy cover were respectively 0.97, 16%, 0.08 and 14.71. The average error in use and not use of Wheat residues for soil salinity was respectively 9.6% and 12.7%, for yield was respectively 6% and 3.5%, for biomass was respectively 4.8% and 3.1% and for canopy cover was respectively 14.6% and 18.8%. The results showed that soil salinity, yield, biomass and canopy cover were simulated well. However, the model accuracy was lower to estimate of soil salinity and canopy cover and it was decreased with salinity increase. Also, the model accuracy was increased in soil salinity and canopy cover estimation and was decreased in yield and biomass estimation under agriculture managements application condition.