Mitigation of Karst Soil Erosion by Optimizing a Biostimulation Strategy to Induce Mineralization

Abstract Karst soil erosion has long been regarded as a major environmental problem in many regions around the world, especially in Southwest China. Based on biomineralization, a biostimulation strategy optimized by the Plackett–Burman (PB) central composite design (CCD) method was proposed to improve the erosion resistance of a red karst clay soil. First, the key components of the stimulation solution were selected by the PB design. Then, a CCD was used to obtain the optimal ratio for each component of the stimulation solution. Finally, surface strength tests, calcium carbonate content tests, infiltration tests, wind erosion tests, and rainfall erosion tests were conducted to evaluate the effect of the biostimulation strategy on red clay erosion resistance and on the mechanical properties of the soil. The influence of cementation solution concentrations and treatment cycles were further analyzed based on test results. The microstructural features of the samples were also analyzed to elucidate the mechanisms of surface erosion control. The results showed that the proposed biostimulation strategy mitigated red clay erosion. Even at a wind speed of 30 m/s, the weight loss of all the biostimulation strategy-treated samples was almost negligible. After 10 cycles of biostimulation treatment, the maximum amount of soil erosion in the rainfall erosion test was reduced by a factor of 10.82. The crust formed on the surface of the samples treated with the biostimulation treatment had higher strength and lower permeability, and it effectively resisted soil erosion. The crust was formed because of binding of the biomineralization product calcium carbonate to soil particles. The higher the calcium carbonate content was, the stronger the erosion resistance of the samples. A comprehensive assessment of the treatment effect, efficiency, and cost showed that 7 cycles of biostimulation treatment with a 1.0 M cementation solution was optimal for the mitigation of red clay erosion.