Effects of Salinity of Magnetized Water on Water–Salt Transport and Infiltration Characteristics of Soil Under Drip Irrigation

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The shortage of fresh water resources and soil salinization restrict the sustainable development of oasis agriculture in Xinjiang, China. Magnetically treated brackish water can physically improve the quality of water used for irrigation, and this technology is being gradually applied in agricultural production. However, the infiltration characteristics of magnetized brackish water and its response to the distribution of soil water and salt are still unknown. We conducted infiltration tests using a one-dimensional soil column system, employing magnetized water at concentrations of 0.2, 1, 3, and 5 g·L⁻1, with a magnetization strength of 3000 gauss (GS), and explored the effects of salinity of magnetized water on water–salt transport and infiltration characteristics of soil under drip irrigation. The migration rate of the wetting front of magnetized water infiltration slowed, and the cumulative infiltration content increased. Specifically, compared to the unmagnetized control, the infiltration time at a depth of 40 cm for magnetized water concentrations of 0.2, 1, 3, and 5 g·L−1 increased by 17.42%, 42.16%, 47.02%, and 39.19%, respectively. Correspondingly, the cumulative infiltration volume increased by 7.88%, 8.09%, 10.60%, and 5.38%. Further, the infiltration of magnetized brackish water increased the water retention capacity of soil, effectively reduced the salt content of soil layers, and had a remarkable desalting effect. Salinity of the soil profile showed an L-shaped trend of salt accumulation in the lower layer and desalting in the upper layer. For water salinity of 3 g·L−1, soil desalting intensity was greatest. In addition, KShf, suction rate, empirical coefficient a, initial infiltration rate, and stable infiltration rate all decreased under magnetization treatment with the same salinity. Thus, this study provides a new way to alleviate the shortage of fresh water resources in arid areas, a guideline for safely using brackish water and also increasing productivity of saline–alkali land.