Effects of Different Fertilization Treatments on Soil Nutrient Availability and Microbial Response Mechanisms in the Baiyinhua Open-Pit Mining Area

• • Microbial fertilizer (MF) significantly increased soil total carbon (TC) from 8.47 to 10.17 g·kg⁻¹ and total nitrogen (TN) from 0.37 to 0.56 g·kg⁻¹, representing a 20.1% and 51.4% increase, respectively, which is critical for establishing a carbon and nitrogen pool in nutrient-poor mine soils. • • High-phosphorus inorganic fertilizer (H) raised available phosphorus (AP) from 9.78 to 26.28 mg·kg⁻¹, a 168.7% increase, directly addressing severe phosphorus limitation (initial AP < 10 mg·kg⁻¹) that constrains plant establishment. • • Both MF and H treatments significantly altered fungal community structure, notably increasing the relative abundance of Gibberella and Alternaria, indicating that nutrient-driven shifts in microbial communities are key mechanisms for enhancing nutrient availability. • • MF treatment achieved these improvements without the ecological risks associated with high inorganic P application (e.g., soil acidification, pathogen proliferation), positioning it as a sustainable bio-based strategy for mine reclamation.