Coal gangue substitution reshapes soil–plant interactions to regulate vegetable growth: implications for recycling industrial waste in sustainable agriculture

BACKGROUND: Excessive reliance on chemical fertilizers has led to soil degradation and environmental risks, highlighting the need for sustainable nutrient management strategies and resource-efficient alternatives. Coal gangue, a major industrial solid waste generated during coal mining, contains various mineral nutrients and has recently attracted attention as a potential fertilizer resource. However, the mechanisms through which coal gangue substitution influences vegetable growth, particularly via soil–plant interactions, remain insufficiently understood. RESULTS: Coal gangue substitution significantly modified soil physicochemical properties, particularly soil pH, organic matter and nutrient availability. Moderate substitution levels enhanced nitrogen and phosphorus uptake, stimulated photosynthetic performance and promoted root growth, ultimately improving plant biomass. Changes in rhizosphere microbial communities further contributed to nutrient cycling and mineral weathering processes. However, excessive substitution levels reduced photosynthetic efficiency despite relatively high soil nutrient levels, suggesting potential physiological constraints under high inputs. Structural equation modeling further revealed that coal gangue influenced plant growth primarily through indirect pathways mediated by soil properties and plant nutrient status. CONCLUSIONS: Overall, moderate coal gangue substitution (25%-50%) provided the most favorable agronomic effects by improving soil fertility, enhancing nutrient utilization and reducing nitrate accumulation in edible tissues. These findings demonstrate that coal gangue fertilization regulates vegetable growth by reshaping soil–plant interactions and provide evidence for its potential application as a sustainable fertilizer alternative. The agricultural utilization of coal gangue offers a promising pathway for transforming industrial solid waste into valuable agricultural resources, thereby supporting circular agriculture and environmentally friendly vegetable production systems.