Simulation soil water-salt flux and irrigation quota for summer maize based on SWAP model in the Northwest China

Abstract Background and aims To investigate the effects of different water-saving irrigation quota on soil water and salt flux under the growth conditions of crop, providing a theoretical basis for the prevention of soil salinization and the efficient utilization of water resources in arid area. Methods The SWAP (Soil-Water-Atmosphere-Plant) model parameters were calibrated and validated based on field experiments data to simulate soil water-salt flux and soil water-salt cumulative flux under different scenarios in the Northwest China. Results Soil water flux, soil water cumulative flux, soil salt flux and soil salt cumulative flux decreased with the decrease on irrigation quota at the lower interface of crop root zone and storage zone under different scenarios. The soil water cumulative flux and soil salt cumulative flux changed small, when the irrigation quota was reduced to 70%IQ (Irrigation Quota) and 60% IQ. Soil water could be stably stored in 0-100 cm soil layer to meet the growth requirements of summer maize, which brought in by irrigation and rainfall. When the irrigation quota of summer maize was 70% IQ (3500 m 3 ·ha − 1 ), soil water-salt flux and soil water-salt cumulative flux were minimal at the lower interface of crop root zone and storage zone. The yield reduction of summer maize was only 10%. Conclusions 3500 m 3 ·ha − 1 was the optimal irrigation quota for summer maize from the perspective of soil water-salt balance and crop growth. It was to provide technical support for the efficient utilization of water resources and also guided agricultural production practice in the Northwest China.