Nature-based Solutions for the Remediation of Sulfentrazone-contaminated Soils: Integrating Macaúba Biochar, Microbial Inoculation, and Canavalia ensiformis

Abstract

Persistent herbicide contamination of soils represents a challenge for sustainable agricultural systems, necessitating efficient remediation strategies. This study evaluated the effectiveness of Canavalia ensiformis associated with macaúba (Acrocomia aculeata) biochar and microbial inoculation for the phytoremediation of the herbicide sulfentrazone. The experiment was conducted under field conditions using a randomized complete block design (RCBD) with a 3 × 3 × 2 factorial arrangement, consisting of three sulfentrazone doses (0, 375, and 625 g a.i. ha⁻1), three remediation strategies (control, biochar, and biochar combined with microbial inoculation), and the presence or absence of C. ensiformis, with four replicates. Gas exchange, chlorophyll fluorescence, photosynthetic pigments, biomass production, and sulfentrazone residues in the soil were evaluated. Herbicide exposure reduced anthocyanin content by up to 44.6% and negatively affected photosynthetic and photochemical parameters at 40 days after sowing. However, physiological recovery was observed at 60 days, demonstrating the tolerance of C. ensiformis to the contaminant. The presence of the species reduced sulfentrazone residues by 74.56%, 80.14%, and 52.38% in the control, biochar, and biochar combined with microbial inoculation treatments, respectively. Considering herbicide doses, residue reductions reached 66.56% and 76.19% at 375 and 625 g a.i. ha⁻1, respectively. These results demonstrate that integrating plants, biochar, and microbial inoculation represents a promising strategy for the sustainable remediation of sulfentrazone-contaminated soils while promoting the valorization of residues from the macaúba production chain within a circular bioeconomy framework.