Biochar as a mitigator of copper toxicity and phytoremediation potential of Swietenia macrophylla King.

Heavy metal contamination promotes soil degradation, reduces fertility, and affects crop growth. Therefore, the use of residues from the açaí (Euterpe oleracea Mart.) agroindustry for biochar production, associated with the cultivation of plants with potential to phytoremediate contaminated soils, such as Brazilian mahogany (Swietenia macrophylla King.), is a promising and sustainable strategy to mitigate the toxic effects of the metal. The study was conducted to evaluate the impact of BCA in mitigating excess Cu, exploring its effects on plant growth and levels, and to investigate the phytoremediation potential of the species exposed to Cu toxicity in the soil. The design was randomized blocks with five blocks, in a 4x3 factorial scheme, with the control treatment (without Cu) and three doses of copper (200, 400, and 600 mg kg-1) and three levels of BCA (0%, 5%, and 10%), totaling sixty experimental units. The application of 5% BCA attenuated Cu toxicity in soils up to 400 mg kg-1, with adequate Cu levels in the aerial part and accumulation in the roots, without compromising the biomass. In addition, Brazilian mahogany has a phytoremediation capacity of Cu up to 200 mg kg-1, and when associated with 5% BCA, it phytostabilized the metal up to a concentration of 400 mg kg-1. The selection of the species and the use of BCA can recover soils contaminated by Cu, being an excellent candidate in recovery programs of areas contaminated by metals in the Amazon.