Una nueva biochar de paja de maíz modificada con hierro mejoró la inmovilización de Cd en el suelo y redujo la...

Cadmium (Cd) contamination poses significant risks to agricultural productivity and ecosystems, necessitating effective remediation strategies. This study evaluated the efficacy of iron (Fe)-modified corn straw biochar (FB) in immobilizing Cd and reducing its uptake in lettuce, compared to raw biochar (B). FB was synthesized by pyrolyzing Fe(NO₃)₃-treated corn straw, and its physicochemical properties were analyzed. Pot experiments were conducted to test Cd immobilization at 0, 1, and 2 mg kg⁻¹ Cd levels with B or FB doses of 0%, 1%, and 3% (w/w) B or FB. FB exhibited higher specific surface area, pore volume, and oxygen-containing functional groups than B. It, enhanced Cd adsorption via mechanisms including surface complexation (-OH, Fe-O), precipitation (CdCO₃), and π-π interactions. Furthermore, FB reduced bioavailable Cd content in soil by 15-28% and shifted Cd speciation from exchangeable forms to Fe/Mn oxide-bound fractions, outperforming B even at lower doses. Additionally, FB improved soil fertility, enzyme activities, and enriched Cd-immobilizing bacteria in the soil, promoting lettuce growth and reducing Cd content in roots (25-40%) and leaves (33-47%). The findings highlighted FB as a cost-effective and sustainable amendment for Cd-contaminated soils, which enhanced adsorption, microbial modulation, and reduced application rates. This study provides critical insights into the dual role of Fe-modified biochar in soil remediation and crop safety, supporting its practical application in sustainable agriculture.