A new study by Saeed et al. published in the journal Environmental Sciences Europe presents a promising strategy to combat the pervasive problem of arsenic (As) pollution in agricultural soils, a concern that has been escalating globally due to the reuse of untreated industrial wastewater for crop cultivation. The research focuses on the combined application of iron-biochar nanocomposites (Fe-BCNC) and a plant growth-promoting rhizobacteria (PGPR), Bacillus sp. (strain MN-54), to detoxify arsenite [As(III)] in soil and mitigate its harmful effects on barley (Hordeum vulgare), a globally important crop. The findings offer a pathway to safeguard both food quality and human health, directly supporting Sustainable Development Goals of zero hunger and life on land.

The researchers observed that arsenic applied to the soil at doses of 25 and 50 mg kg⁻¹ caused significant phytotoxicity in barley, severely restricting growth and worsening key physiological and biochemical indicators. However, the application of Fe-BCNC and PGPR dramatically countered these effects. The synergistic action of the two amendments proved superior to individual treatments. Specifically, the combined treatment resulted in substantial improvements in plant growth parameters even under high arsenic stress. For example, in soil contaminated with 50 mg kg⁻¹ As, the combination of Fe-BCNC and PGPR increased plant height by 52% and root length by 91%. Critically, the treatment boosted the essential quality of the harvest, increasing grain weight by up to 76% and crude protein in the grains by up to 59% compared to contaminated control groups. This suggests that the treatment not only helps the plant survive the stress but enables it to thrive and produce a more nutritious yield.

The core mechanism involves the successful reduction of arsenic’s bioavailability and translocation within the soil-plant system. The combined Fe-BCNC and PGPR treatment enhanced arsenic immobilization in the soil by up to 47%. The most significant shift was observed in the arsenic fractionation profile, where the metal was preferentially bound to the iron, aluminum, and manganese oxide fraction, effectively locking it into a less mobile and non-bioavailable form. This immobilization is partly facilitated by the Fe-BCNC, which, as confirmed by X-ray diffraction and Fourier-transform infrared spectroscopy, successfully coats the biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More surface with iron. The PGPR, Bacillus sp., contributes by converting the more mobile and toxic arsenite (As(III)) into the less mobile arsenate (As(V)), which is then readily adsorbed by the iron-rich nanocomposite.

The physiological response of the barley plants further underscores the protective effect. Arsenic stress typically causes a surge in plant stress markers reflecting severe oxidative stress and cellular damage. The combined Fe-BCNC and PGPR application significantly reduced the activity of these antioxidant enzymes, decreasing POD activity by up to 30%, indicating a substantial mitigation of oxidative stress. The treatment also improved physiological attributes like relative water content and chlorophyll contents, suggesting a healthier, more functional plant overall.

Most importantly, the intervention yielded profound benefits for end-consumer health. The combined application reduced arsenic accumulation in the barley grain, shoot, and root tissues. This decrease in arsenic levels translated directly into a drastic reduction in associated health risks. The treatment lowered the Health Risk Index (HRI) by up to 94% and the Integrated Lifetime Cancer Risk (ILTCR) by 94 times compared to contaminated but untreated soil. With ILTCR values dropping for the two contamination levels, the combined use of Fe-BCNC and PGPR offers a sustainable, cost-effective, and effective approach for phytostabilizing arsenic-polluted agricultural soils, ensuring the safety and nutritional quality of the food produced.

Source: Saeed, R. A., Naveed, M., Ghafoor, A., Munir, M., Alqahtani, N., Ali-Dinar, H., Mustafa, A., & Núñez-Delgado, A. (2025). Mitigation of arsenite toxicity in barley using iron-biochar nanocomposites and Bacillus sp.: impacts on soil immobilization, plant stress, and health risk. Environmental Sciences Europe, 37(220).