Shuai Chen, Zunqiu Xu, Chunying Wang, Songhao Shang
Water flow, solute transport, and crop responses are essential physical and biological processes in cropland, which become more complicated under film mulched drip irrigation. To simulate these interactive processes, we developed a new model by coupling a two-dimensional water flow and solute transport model with a crop growth model (WSP-2D). The WSP-2D considered infiltration/evaporation flux through planting holes of mulched film to replace the commonly adopted no flux condition. Two-dimensional root growth was quantified with the crop growth day and coupled to the root water uptake distribution model to strengthen the interaction in depicting the soil-plant system. The developed model was calibrated and verified by measured data from a two-year field experiment under film mulched drip irrigation in Northwest China. The field soil water and salt dynamics, leaf area index, biomass, and crop yield were well captured by the coupled model, with the coefficient of determination of greater than 0.90, 0.48, 0.90, and 0.98, respectively. Scenario simulations indicate that the simulated soil water content and salt concentration matched better with measurements when evaporation and precipitation rates were considered for film mulched zone. The simulations with a fixed root distribution overestimate soil water content up to 21.8 % and underestimate salt concentration up to 43.5 % in the top layer of the root zone, while underestimate the soil water content and overestimate salt concentration in the lower layer of the root zone. Salt mainly accumulated in the upper loam layer with an underlying sand layer and in the soil beneath the plant row due to transpiration. In conclusion, the WSP-2D considers more interactive processes in the soil-plant system under film mulched drip irrigation condition and better simulate these processes.