Integrating Plant Growth-Promoting Rhizobacteria with Coal-Preparation Waste for Mine Soil Reclamation

This study evaluated coal-enrichment plant refuse (CEPR) as an amendment combined with plant growth-promoting rhizobacteria (PGPR). Einkorn wheat was grown in a 5 × 2 factorial experiment comprising five CEPR application rates (0%, 5%, 10%, 20%, and 40%) and two PGPR treatments (PGPR− and PGPR+). In addition to plant growth parameters, growing-medium pH and salinity, as well as plant macronutrient, micronutrient, and potentially toxic trace-element concentrations, were evaluated. PGPR increased plant height, fresh biomass, and dry biomass by 285%, 200%, and 270%, respectively, while increasing K, Zn, and Mn concentrations by 132%, 337%, and 53%, respectively; total uptake of these elements was also higher under PGPR treatment. CEPR increased growing-medium pH from 7.54 to 8.03 without increasing salinity risk. Moderate CEPR rates (5%–10%) produced the most favorable growth responses, whereas higher rates (20%–40%) were associated with reduced growth and increased growing-medium pH. Ni and Cd concentrations in plant tissues varied across treatments; these measurements alone do not establish the long-term environmental safety of CEPR application. Under the conditions of this short-term pot experiment, the 5%–10% CEPR treatments showed the most favorable plant-growth responses when combined with PGPR. These findings identify a treatment range for further investigation; its suitability for mine-soil reclamation requires longer-term field testing across different soils and CEPR sources, including assessment under weathering, rainfall, and seasonal variation.