Grasslands disturbed by mining activities in alpine regions exhibit slow recovery under natural conditions. Although organic amendments have been demonstrated to improve soil structure and water retention， their medium- to long-term effects on soil nutrient dynamics and microbial community composition remain unclear. This study investigated the regulatory effects of an organic amendment on the physicochemical properties and microbial community structure of grassland soils in high-altitude mining areas. The results showed that the organic amendment significantly enhanced soil moisture retention and nutrient accumulation. After three years of restoration， soil water content， particulate organic carbon （POC）， and total nitrogen （TN） at a depth of 25 cm increased by 17.07%， 22.86%， and 24.72%， respectively. Despite the gradual decomposition of the organic amendment in surface soil over time， its beneficial effects persisted in deeper layers. Additionally， the organic amendment improved bacterial community composition by increasing the relative abundances of Proteobacteria， Actinobacteria， and Acidobacteria. Mantel tests and redundancy analysis （RDA） further revealed that the organic amendment enhanced the positive correlations between soil nutrient parameters and microbial community structure， thereby facilitating microbial succession and ecological functional recovery.

Alpine grassland degradation  /  Mining disturbance  /  Organic amendment  /  Soil nutrients  /  Microbial community