Effects of Chlorophytum comosum Combined with Pteroceltis tatarinowii Biochar on Farmland Soil Remediation in Cu-Pb Mining Areas and Lettuce Growth

Abstract

Plant-biochar remediation is a promising strategy for heavy metal-contaminated farmland, but its practical value should be evaluated by considering both residual soil risk and the response of subsequently planted crops. In this study, waste-derived Pteroceltis tatarinowii Maxim. (PTM) biochar was combined with the non-food accumulator Chlorophytum comosum (C. comosum) to remediate field-collected Cu-Pb-contaminated soil. Lactuca sativa (L. sativa) was subsequently planted as a sensitive indicator crop. Among the treatments, the combined application of 5% PTM biochar and C. comosum (BC5) produced the strongest overall remediation effect. BC5 improved the growth of L. sativa, increased leaf chlorophyll content, decreased malondialdehyde content and antioxidant-enzyme activities, and reduced Cu and Pb uptake and translocation (P < 0.05). BC5 also reduced the bioavailable fractions of Cu and Pb in soil and was associated with shifts in bacterial community structure, increased relative abundances of Bryobacter and Vibrionimonas, and changes in predicted metabolic pathways related to nutrient cycling and stress regulation. These microbial responses may help explain the improvement in soil ecological function and the reduced metal stress in L. sativa, although further functional validation is needed. Overall, sequential remediation using PTM biochar and C. comosum provides a potential low-cost and eco-friendly approach for reducing residual phytotoxicity and crop metal-uptake risk in Cu-Pb-contaminated farmland.