Effects of Irrigation with Magnetized Saline Water on Soil Aggregate Size Distribution and Stability

Saline water irrigation is increasingly used in arid regions, but its influence on soil aggregate stability remains uncertain when combined with magnetization pretreatment. A two-year field-pit experiment was conducted during 2024–2025 with four magnetization intensities (0, 0.2, 0.4, and 0.6 T) and three irrigation water salinity levels (≤1, 3, and 6 g L−1). Mechanically stable and water-stable soil aggregates were analyzed in the 0–60 cm soil profile. Magnetization treatments changed aggregate-size distribution, but the dominant response differed between aggregate types. Mechanically stable aggregates mainly showed an increase in the >2 mm fraction and a decrease in the 0.053–0.25 mm fraction, whereas water-stable aggregates mainly showed an increase in the 0.25–1 mm fraction and a decrease in the <0.053 mm fraction. The percentage of aggregates > 0.25 mm (R0.25), mean weight diameter (MWD), and geometric mean diameter (GMD) varied with soil depth, salinity level, and year. Under S6, C4S6 increased the R0.25 of mechanically stable aggregates in both years, reaching 73.90% in 2025 compared with 61.60% under C0S6. Correlation and exploratory path analyses suggested that changes in aggregate stability were mainly associated with the redistribution of key aggregate-size fractions. Under the field-pit conditions of this study, some magnetization treatments, particularly 0.4 T, were often associated with higher stability indices than non-magnetized saline irrigation, but this pattern was not consistent across all depths, salinity levels, years, and indicators. Long-term open-field validation is still required.