Long-term integrated water-saving agricultural practices enhance soil health and sustain cotton yield on saline-alkali reclaimed lands

Reclamation and management of saline wastelands are crucial for enhancing soil quality and agricultural productivity. Integrated water-saving agricultural practices (IWAP) have shown positive effects on saline-alkali soil improvement. However, the long-term yield response mechanisms, particularly the causal relationships between integrated practices, holistic soil health (physical, chemical, and biological), and microbial drivers, remain poorly understood. This study compared fields reclaimed for 12, 17, 20, 22, and 27 years with adjacent uncultivated saline-alkaline wasteland as the control, focusing on the cumulative effects of IWAP. Soil physical, chemical, and biological properties were assessed alongside soil health scores (Cornell Soil Health Assessment, PCA) and seed cotton yield for the 2023 season. The results showed that after reclamation, the soil salt content (SSC) in the 0–20 cm layer decreased by 82.07 %93.19 %, and total carbon (TC), nitrogen (TN), and phosphorus (TP) content increased significantly. In the 20–60 cm layer, salinity decreased by 63.13 %89.19 %, and TC, TN, and TP also increased. Soil health scores (SHS) increased by 202.66 %322.11 % in the 0–20 cm layer and 155.09 %277.48 % in the 20–60 cm layer, with the topsoil showing greater improvement. Soil aggregate stability followed a "decrease-then-increase" trend, reaching the lowest values at 12 years and gradually recovering there-after. PLS-SEM analysis revealed that IWAP directly impacted WSA> 0.25, SSC, and soil organic carbon (SOC), driving improvements in SHS and seed cotton yield. Key soil attributes such as WSA>0.25, SOC, microbial biomass carbon (MBC), and phosphorus (MBP) played pivotal roles in enhancing soil health and boosting yield. However, inefficient salt leaching and fluctuating microbial activity in the subsoil indicate areas for improvement in current practices. These findings not only decipher the mechanisms behind yield enhancement on reclaimed lands but also provide a robust scientific for optimizing management strategies to advance sustainable agroecosystems in saline-alkaline regions globally.