Changes in soil quality during different ecological restoration years in the abandoned coal mine area of southern China

Understanding the effects of abandoned coal mine ecological restoration on soil quality and function is important to protect the regional ecological environment. This study aims to evaluate the ecological restoration effects of soil quality in abandoned coal mine area. Taking Fengcheng County, a typical coal-rich area in southern China, as a case, this study took 120 soil samples to investigate the influence of restoration years on soil quality by using an integrated soil quality index (SQI). Results indicated that restoration years had significant effects on the saturated hydraulic conductivity (Ks) by affecting the soil bulk density, clay content, and soil water content. Furthermore, clay, soil organic matter, Ks, and pH were selected to assess the effect of ecological restoration years on soil quality. It was found that the ecological restoration 8 years (ER8) site had higher SQI value, indicating ecological restoration years showed a positive correlation with SQI in abandoned coal mine area. Since there was a 4-year gap between ecological restoration 4 years site and ER8 site, the ecological restoration may be effective between 5 and 8 years. The results of this study are of great significance for improving the effects of ecological restoration and management in abandoned coal mine area.