Rationale saline-water irrigation also serves as enhancing soil aggregate stability, regulating carbon emissions, and improving water use efficiency in oasis cotton fields

Saline water irrigation has been applied in arid regions with abundant natural saline water resources to mitigate water scarcity. However, the impacts of saline water irrigation on soil aggregate stability—a pivotal factor for improving irrigation efficiency and crop yields—has not been sufficiently investigated. Therefore, three levels of saline water were used in the cotton field signifying as T1 (3 g·L −1 ), T2 (5 g·L −1 ), and T3 (8 g·L −1 ), with the freshwater as the controlled group (CK) in this study. The results uncovered that the escalating irrigation water salinity led to augmentations in soil surface salinity and pH value, accompanied by the decline in soil organic carbon (SOC), total nitrogen (TN), total potassium (TK), available nitrogen (AN), and available potassium (AK) contents. Conversely, the mean weight diameter (WMD) and geometric mean diameter (GMD) of large soil aggregates (R 0.25 ) exhibited an upward trend, peaking at T2. The concentrations of K + , Ca 2+ , Na + , Mg 2+ in aggregates of varying particle sizes rose in line with increased salinity, reaching the highest in T3, particularly in aggregates larger than 2 mm. Notably, the Ca 2+ /Mg 2+ ratio was higher in smaller particle sizes (< 0.25 mm), indicating a concentration of base cations in larger aggregates under saline water irrigation. Furthermore, soil respiration rate and cumulative CO 2 emissions declined significantly with rising salinity, with T3 showing a 27.79 % reduction in cumulative CO 2 emissions compared to CK. Moreover, cotton yield and irrigation water use efficiency initially rose before declining with increasing saline water levels, peaking at T1.Based on the above findings, an irrigation water salinity threshold of ≤ 3 g·L −1 is proposed for sustaining soil aggregate stability, cotton productivity, and water efficiency. Our research offers theoretical justification for policymakers to develop a practical and sustainable saline water application strategies in arid oasis regions. • Saline water irrigation affects the soil properties and base cation distributions. • Irrigation salinity below 5 g·L −1 can temporarily enhance the soil aggregates stability. • Salt base cations mainly concentrate in big soil aggregates. • Excessive saline water impedes soil respiration and carbon emissions in cotton fields. • Irrigation salinity of 3 g·L −1 is the threshold to maintain cotton yield and water use efficiency.