Effect of the mineral-microbial complexes on the quality, soil nutrients, and microbial community of tailing substrates for growing potted Rorippa

With China's industrialization and a rapidly developing coal industry, tailings have become one of the most widely distributed solid wastes, responsible for degrading available land and damaging the surrounding ecological environment. This study investigated the effect of adding mineral-microbial complexes to tailing substrates for the improvement of plant growth and substrate microbial community. The results revealed that compared with other treatments, the growth of Rorippa was considerably better after the addition of mineral-microbial complexes to the substrate, indicating that the mineral-microbial complexes promoted plant growth. After the addition of mineral-microbial complexes, the fertility indicators of the substrate showed a substantial improvement, in addition to the pH and organic matter (OM). The addition of fertilizers to the substrate plays a key role in plant growth, whereas the addition of microbial supplements to the substrate alone has little effect on plant growth. The results of high-throughput sequencing showed that the main microbial communities present in the substrate were Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, and Nitrospirae. The results of the microbial community α-diversity analysis showed that the addition of the mineral-microbial complexes improved the abundance and diversity of the substrate microbial community. Results of the microbial community β-diversity analysis indicated that the experimental group showed a higher correlation with the microbial community relative to the background group. Network analysis revealed similar correlations between microbial communities and environmental factors, and total phosphorous (TP)-pH-available potassium (AK)-available nitrogen (AN) and TP-electronic conductivity (EC)-AK-AN were the main drivers of microbial communities in the background and experimental groups, respectively. The findings of this study provide a theoretical basis for the resource utilization of tailings and vegetation restoration using tailings.