IntroductionMining waste dumps in tropical regions suffer severe ecological degradation with plant growth inhibition, yet the synergistic limiting factors remain unclear.MethodsThis study systematically assessed a tropical mining waste dump (Democratic Republic of the Congo), analyzing soil physicochemical properties, total/bioavailable metals, and microbial community structure/function of four soil types (KE, PG, TS, YS), alongside on-site water quality.ResultsResults showed three core limiting factors for plant growth: (1) Severe metal phytotoxicity, with KE's bioavailable Cu (261.4667 mg/kg) exceeding the toxicity critical value and TS's total Cu/Co surpassing USEPA screening levels; (2) Deteriorated soil physiochemistry, including water content imbalance, severe salinization in PG, and extreme N/P/K deficiency in KE/TS/YS; (3) Microbial community dysfunction, featuring low α-diversity, dominance of metal-tolerant genera, scarce plant growth-promoting rhizobacteria, and weak nutrient cycling functions. These factors formed a "toxicity-deficiency-dysbiosis" vicious cycle. Notably, on-site water met WHO standards, suitable for restoration irrigation. Correlation analysis revealed bioavailable metals shaped microbial communities, and PG's salinization stemmed from abnormal K/S accumulation.Discussion and ConclusionTargeted restoration measures (metal immobilization, soil physicochemical improvement, microbial function enhancement) were proposed. This holistic study fills the gap in tropical mining waste dumps, providing scientific support for ecological risk assessment and restoration of similar regions globally.