A novel strategy employing lignin biochar to simultaneously promote remediation and safe crop production in Cd-contaminated soil

Abstract

The scarcity of arable land and the problem of food security urgently called for a strategy of Remediation-by-Production (RBP). Biochar is a promising method for addressing Cd-contaminated soils, but the time required for remediation and the variability of long-term performance have a direct impact on the realization of the RBP strategy. We have developed a novel approach for remediating cadmium-contaminated flooded soil by utilizing lignin biochar (LBC) in combination with safe rice cultivation. The addition of 1 % LBC achieves efficient Cd passivation (CP: 90.89 %) before rice Cd uptake peaks. Meanwhile, LBC can increase soil organic matter and alter microbial community structure, decreasing the relative abundance of soil pathogenic bacteria from 5.12 % to 4.03 % while raising nutritional bacteria from 15.18 % to 28.82 %. Furthermore, LBC successfully reduced the accumulation of Cd in rice grains by 31.3 % ∼ 54.6 %, making rice dwarf, sturdy, and greener, and lowering the health risk coefficients of Cd across various age groups by Monte Carlo simulations. This study elucidated the critical role of humic substances of LBC in remediation time and performance and laid a solid theoretical foundation for promoting the application of biochar in soil contamination remediation and simultaneously realizing the safe production of crops.