Magnetically-treated brackish water affects soil water-salt distribution and the growth of cotton with film mulch drip irrigation in Xinjiang, China

Magnetically-treated brackish water can physically improve the quality of water used for irrigation. When combined with drip irrigation and mulching, this strategy can be valuable for agricultural production in arid and semi-arid areas. To evaluate the effects of magnetically-treated brackish water on soil water-salt distribution and cotton growth in Xinjiang, field experiments were conducted in 2017 and 2018 with magnetically-treated brackish water of five magnetization intensities: 0 Gs (CK), 1000 Gs (G1), 2000 Gs (G2), 4000 Gs (G4), and 5000 Gs (G5). The results showed that magnetically-treated brackish water (2.7 g L-1 (EC: 0.6 dS m(-1))) could enhance soil water retention, promote root water absorption, and improve water productivity (WP). Magnetically-treated brackish water with 4000 Gs intensity showed the greatest improvement in water retention in the 0-100 cm soil layer. The average salt content in the soil irrigated with magnetically-treated brackish water of different intensities was in the order G4 < G2 < G5 < G1 < CK, indicating that magnetically-treated brackish water can effectively reduce the salt content and promote salt leaching. The desalinization rate, cotton yield, and WP were highest when the magnetization intensity was 4000 Gs, followed by 2000 Gs, which helped to alleviate the shortage of freshwater resources and reduce the risk of soil salinization. This study could provide a method for using brackish water safely and serve as a theoretical guide for water-saving and cotton yield increase in Xinjiang, China.