Utilizing ragweed and oyster shell derived biochar as an effective stabilizer for the restoring Cd and Pb- contaminated soil

Abstract

This study aimed to compare the effects of limestone and biochar amendments on heavy metal availability, soil fertility, and crop yield in cadmium (Cd) and lead (Pb) contaminated soil. A pot experiment with Chinese cabbage was conducted to evaluate two types of biochar derived from invasive plant (ragweed) and oyster shells for their potential in stabilizing Cd and Pb. The results showed that both biochar amendments significantly reduced the availability and uptake of Cd and Pb in soil and cabbage, comparable to the effects of limestone. Moreover, biochar amendment synergistically enhanced soil fertility, cabbage yield and quality. Application of ragweed-derived biochar at a 0.5% dosage consistently and most effectively promoted leaf biomass by 18% and 25% and increased vitamin C levels by 20% and 30% at harvest 1 and 2, respectively. Additionally, it led to a reduction in leaf content of nitrate by 26% and 37%, as well as a decline in Cd content by 41% and 21% and Pb content by 78% and 58%. Notably, despite the increased application cost, ragweed-derived biochar has far greater financial benefits than lime due to increased crop yield. These findings highlight the potential of employing natural and high-performance biochar with multiple functionalities, offering benefits not only in controlling invasive species and managing waste but also as a promising substitute for lime application, thereby contributing significantly to sustainable soil management.