Impact of Compound Organic Fertilizer–Plant Combined Remediation on Microbial Community Structure in Mine Tailings Substrates

Ecological restoration is increasingly applied as an effective strategy for mitigating environmental risks associated with tailings impoundments. However, plant establishment and ecological recovery in tailings substrates are often limited by unfavorable physicochemical properties and potential toxicity. This study investigated the changes in soil microbial community structure and diversity under the synergistic remediation of compound organic fertilizer and plants. Field plots subjected to combined organic fertilizer–plant remediation in a tailings impoundment in northern China were selected. The high-throughput sequencing of bacterial 16S rRNA genes and fungal ITS regions was performed alongside analyses of soil physicochemical properties. Compared to the untreated tailings soil, remediated soils showed pH values closer to neutrality, lower electrical conductivity, and significantly higher organic matter content, indicating an overall reduction in environmental stress and potential toxicity. The relative abundance of copiotrophic bacteria, such as Proteobacteria, increased, whereas that of stress-tolerant taxa adapted to extreme environments, such as Firmicutes , decreased. Although slight variations in dominant groups were observed among plots with different plant species, key microbial groups contributing to soil environmental improvement were largely consistent. These findings demonstrate that this combined remediation effectively improves the physicochemical properties and microbial community structure of tailings soil, providing a risk-oriented and ecologically sustainable strategy for the ecological restoration of similar sites.