Enhancing soil structure and water dynamics through long-term mulched drip irrigation in arid reclaimed saline soils

Soil salinization is a global environmental issue, and in the arid regions of Xinjiang, China, mulched drip irrigation (MDI) has been extensively implemented to combat drought and improve agricultural productivity on reclaimed saline wastelands. Despite its extensive use, the long-term impacts of MDI on soil physical properties and hydraulic characteristics remain underexplored. This study examines these long-term effects in cotton fields over 11, 16, 19, 21, and 26 years. Initial results showed significant improvements, including increases in soil moisture content (7.7 %–12.11 % to 8.1 %–14.58 %), a decrease in soil bulk density (1.66–1.79 g cm −3 to 1.34–1.49 g cm −3 ), and an increase in total soil porosity (34.80 %–38.49 % to 44.50 %–50.47 %). However, after 19 years of continuous MDI application, improvements in soil properties plateaued. The geometric mean diameter (GMD), macro-aggregate content, and mean weight diameter (MWD) initially decreased during the first 11 years but improved thereafter. The Soil Structural Stability Index (SI) significantly increased with ongoing MDI application. MDI also enhanced soil water retention and hydraulic conductivity, with saturated hydraulic conductivity (K s ) and saturated water content (θ s ) peaking during the initial and middle phases (11, 16, and 19 years), before diminishing in the later stages (21 and 26 years). Furthermore, MDI elevated soil organic carbon (SOC) levels and aggregate stability, bolstering soil resistance against degradation. Pearson correlation and principal component analyses underscored a positive relationship between SI, K s , θ s , SOC, and aggregate stability. This study confirms that MDI can effectively improve soil structure and dynamics, though its long-term sustainability requires periodic reassessment. These findings offer valuable insights into soil management strategies for achieving the UN's SDGs under similar environmental conditions.