Objective In recent decades, rapid mineral resource exploitation in China has severely disrupted surface vegetation, altered hydrogeological structures, and degraded local ecosystems. In mountainous plateau regions such as Yunnan province, extensive bare rock slopes—often in high-rainfall zones—have emerged. These disturbed slopes are highly susceptible to landslides, rockfalls, and severe soil erosion, posing long-term threats to both ecological integrity and human safety. There is an urgent need for eco-friendly, cost-effective restoration materials that can enhance slope stability while promoting ecological recovery. Cassava starch, a renewable biopolymer, and peat, an organic-rich substrate with high water and nutrient retention, show potential for such applications. However, their synergistic effects, particularly in improving residual lateritic soils in high-altitude environments, remain poorly understood. To address the problems of fragile ecological environment, poor stability, and insufficient soil and water conservation capacity of abandoned rock slopes in mining areas of Yunnan province, a specialized ecological restoration substrate is developed through laboratory tests, aiming to improve the mechanical and ecological performance of slopes after restoration and enhance slope soil and water conservation and vegetation restoration capacity.

Methods In this study, residual lateritic soil from a mining site in Yunnan was amended with cassava starch, peat, wheat straw, sawdust, and compound fertilizer. Laboratory tests—including direct shear, permeability, water retention, erosion resistance, and plant growth experiments—were conducted to systematically evaluate the mechanical and ecological performance of various amendment mixtures. The entropy weight method was applied to integrate multiple evaluation indicators and determine the optimal amendment ratio.

Results Experimental results indicated that cassava starch significantly increased soil shear strength, with the highest increase of 18.9% observed at a 3% content; however, in the composite substrate containing all amendments, the most significant effect was achieved at a cassava content of 1%. Cassava starch also notably decreased soil erosion rates, achieving a reduction from 77.53% in untreated soil to 4.82% at the highest content tested. Water retention was enhanced, reaching a maximum rate of 28.04% at a cassava content of 3%. In terms of permeability, the addition of various materials reduced the permeability coefficient by nearly an order of magnitude compared to the untreated residual lateritic soil. Plant growth trials demonstrated that while increased peat content slightly suppressed seed germination, it greatly increased plant biomass, reaching a peak biomass of 12.18 g. According to the entropy weight analysis, formulation B1 (1% cassava starch and 5% peat) achieved the highest comprehensive performance score.

Conclusions The proposed amended substrate effectively enhances the mechanical strength, water-holding capacity, erosion resistance, and revegetation performance of mine slopes. Moreover, it provides an optimal formulation for practical engineering applications, demonstrating significant potential and ecological value for mine slope revegetation and soil and water conservation.