Effects of sprinkler irrigation intensity with brackish water on water–salt transport in the soil profile and yield of winter wheat: A field experiment and HYDRUS-1D simulation

To clarify how sprinkler irrigation intensity affects water–salt transport in the soil profile and winter wheat yield under brackish-water irrigation, a field experiment was combined with HYDRUS-1D simulations under an equal irrigation amount. Two irrigation water salinity levels (3 and 5 g L⁻¹) and five sprinkler irrigation intensities (1.8, 3.2, 4.8, 6.5, and 8.2 mm h⁻¹) were evaluated. Irrigation water salinity, sprinkler irrigation intensity, growth stage, and soil depth significantly affected soil water content and electrical conductivity (EC), with treatment differences concentrated mainly in the 0–40 cm soil layer. HYDRUS-1D reproduced the main features of soil water–salt dynamics. Calibration and validation produced R values of 0.78–0.89 and Nash–Sutcliffe efficiency values of 0.48–0.75. Under 3 g L⁻¹ , yield at 4.8 mm h⁻¹ was 9886.34 kg ha⁻¹ and did not differ significantly from the fresh-water control. Under 5 g L⁻¹ , yield reductions were smaller at 4.8 and 6.5 mm h⁻¹ than at the other intensities. Under the soil, climatic, and sprinkler-configuration conditions of this experiment, with each irrigation event consisting of 18 mm of brackish water immediately followed by 18 mm of freshwater, 4.8 mm h⁻¹ provided relatively good overall performance with 3 g L⁻¹ brackish water, whereas 4.8 and 6.5 mm h⁻¹ performed relatively better at 5 g L⁻¹ . These intensities may serve as starting parameters for field trials under similar conditions and should be adjusted according to soil water–salt monitoring, freshwater leaching conditions, and crop yield responses.