Modifying Soil Plasticity Using Biochar to Prevent Soil Erosion

Soil erosion has been increasing dramatically across the US, with an estimated loss of 2 billion tons of farmland soil and coastal recession rates ranging from 8 to 15 m per year. Traditional stabilizers, such as lime and cement, are commonly used to reduce soil erodibility but contribute significantly to greenhouse gas (GHG) emissions. In this study, biochar, a low-emission alternative, was used to modify soil plasticity to reduce erodibility. Soil samples consisted of sand and commercial bentonite mixed at varying weight percentages to simulate different plasticity. Biochar was added at a dosage of 2% by weight of the dry soil mixture. Two types of biochar were adopted including raw biochar and calcium-treated (engineered) biochar. Atterberg limits tests were performed to assess the effectiveness of biochar in reducing erodibility. Results showed that engineered biochar significantly enhanced soil plasticity compared to commercial biochar, particularly when the initial plasticity index was below 25. However, improvements were insignificant when the soil plasticity index was greater than 40.