Soil Salt Accumulation, Physiological Responses, and Yield Simulation of Winter Wheat to Alternate Saline and Fresh Water Irrigation in the North China Plain

Large amounts of shallow underground water typically with salt content at around 4.7 dS m⁻¹ are available in the North Chain Plain (NCP), which requires managing and thus can be properly used in irrigated agriculture to relieve the increasing pressure on fresh water in this region for supplementary irrigation. Field experiments were conducted to investigate the soil salt accumulation, responses, and yield simulation of winter wheat to the alternate irrigation strategies during 2017–2019. Five irrigation strategies included rain-fed cultivation (NI), fresh and saline water irrigation (FS), fresh water irrigation (FF), saline water irrigation (SS), and saline and fresh water irrigation (SF) during the growth stages. Irrigation with saline water increased soil salinity level and could be balanced annually; however, the leaf gas exchange of winter wheat was almost not significantly affected. The salinity caused by saline water irrigation negatively influenced the vegetative growth. The grain yield was increased by 24% and 32% under the FS and SF treatments compared to NI, while a minor reduction by 12% and 5% in yield under these treatments was recorded compared with the FF treatment. The SALTMED model was calibrated and validated to predict yield, and the high value of the R² reflected a good agreement between modeled and observed values, indicating that the SALTMED model was able to simulate grain yield under the alternate irrigation strategies in the regional climate condition. Supplementary irrigation using saline water at the stem elongation stage and fresh water at the flowering stage is a practical solution to achieve comparable yields with low risk of salt accumulation for winter wheat particularly in the NCP.