Novel multi-interface regulation of acetochlor fate in a soil-plant system using N-doped biochar-modified zero-valent iron nanocomposites for enhanced degradation and protective root iron plaque formation

Agricultural herbicide contamination in soil poses a significant challenge to global food security and ecosystem health. However, conventional remediation strategies often neglect the co-control of parent compounds and their more mobile transformation products, thereby increasing the risks of crop uptake and incomplete detoxification. Here, we have developed a novel nitrogen-doped biochar-modified zero-valent iron nanocomposite (NC-ZVI) that enables multi-interface regulation of pollutants in soil–plant systems, simultaneously promoting soil remediation and safeguarding crop health. Engineering of atomic Fe–C and Fe–N coordination along with N-doped active sites modulated the electronic structure of ZVI, enhancing the surface reactivity and electron capability in NC-ZVI. This enabled rapid removal of approximately 90% of acetochlor in soil within 7 d by reinforced interfacial catalytic degradation. NC-ZVI also promoted the release of iron ions, driving the formation of iron plaques on maize root surfaces. These plaques established a dynamic protective barrier that reduced the total concentrations of acetochlor and its degradation products in maize by 81.2% while maintaining iron nutrient uptake. The multi-interface interaction strategy not only restored maize productivity, increasing its aboveground biomass by 208.4%, but also preserved soil microbial diversity, all at a cost-competitive level. Overall, this work advances the understanding of the interactions between biochar-based materials and pollutants in soil–plant systems, providing a powerful tool to tackle soil pollution and enhance food safety.