Safe Production of Rice (Oryza sativa L.) in Arsenic-Contaminated Soil: a Remedial Strategy using Micro-Nanostructured Bone Biochar

This study investigated the effects of fine-sized pork bone biochar particles on remediating As-contaminated soil and alleviating associated phytotoxicity to rice in 50-day short-term and 120-day full-life-cycle pot experiments. The addition of micro-nanostructured pork bone biochar (BC) pyrolyzed at 400 and 600 °C (BC400 and BC600) significantly increased the As-treated shoot and root fresh weight by 24.4–77.6%, while simultaneously reducing tissue As accumulation by 26.7–64.1% and increasing soil As content by 17.1–27.1% as compared to As treatment. Microbial community analysis demonstrated that BC600 and BC400 treatments increased the proportion of plant growth-promoting microbes such as Ceratobasidium and Achromobacter by 33–81.6% in the roots and As adsorption-associated Bacillus by 1.15–1.59-fold in the rhizosphere soil. Metabolomic profiling suggests that BC and As coexposure triggered differentially expressed metabolites (DEMs) enriched in lipid, carbohydrate, and amino acid metabolic pathways, all of which could alleviate As-induced phytotoxicity and promote plant As tolerance. Importantly, the quality of As-treated rice grains was improved by the BC amendments. This study demonstrates the significant potential of BC for enhancing crop growth and minimizing the As-induced phytotoxicity to rice and provides a framework for a promising strategy for remediating heavy metal(loid)-contaminated soil while simultaneously promoting food safety.