Reclamation of Iron Extraction Site with Organic Residues and Phytocapping with Sesbania sesban and Its Impacts on Microbial Ecology

Mining soils often suffer from low biodiversity, poor organic matter, and environmental disturbances, which hinder seed germination and plant growth. This study utilized composting and phytocapping approaches to reclaim Fe tailing soil at field scale through addition of different organic residues and Sesbania sesban plant. The improvement of soil quality parameters including pH, soil organic matter (SOM), electrical conductivity (EC), cation exchange capacity (CEC), total N, total P, total microbial count, organically bound Fe, total Fe in soil, and in different parts of the plant were analyzed for 90 days. Organically bound iron was analyzed through Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and microbial community dynamics through 16S rRNA genome sequencing. All treatments showed highly significant difference (p < 0.05) in the pH values compared to C, while within treatments negligible changes in the pH was observed. In case of SOM, organically and plant treated samples showed significant increase as compared to C sample, similarly N, P content, EC, CEC and microbial count, total Fe and organically bound Fe were also significantly increased. The shift of microbial community from lithotrophs to organotrophs was observed compared to control which showed higher abundance of chemolithotrophs. It is concluded that the addition of organic matter enhanced the iron tailing properties along with iron mineralization, while S. sesban has further improved this process and uptake iron efficiently. These findings suggest treatment strategies applicable not only to iron mining sites but also to other extraction sites, including Cu and Pb.