Abstract
Soil pollution by heavy metals is a significant issue impacting food security and human health. Cadmium, a toxic metal, contaminates soils via industrial and agricultural activities, posing risks to the food chain. This study aimed to evaluate methods for reducing cadmium bioavailability in bread wheat and durum wheat, crucial crops for human nutrition grown on contaminated soils. A greenhouse experiment was conducted in which soil samples were treated with 3-6% natural bentonite and sodium-enriched bentonite and contaminated with 5 and 10 ppm cadmium. Compared to controls, cadmium bioavailability in bread wheat decreased by 55% with 5 ppm of Cd and by 66% with 10 ppm of Cd when treated with 6% sodium-enriched bentonite. Similarly, in durum wheat, cadmium bioavailability decreased by 55% and 48% at 5 and 10 mg Cd kg(-1), respectively. Additionally, 6% natural and enriched bentonite applications increased biomass production in both wheat varieties. Bread wheat dry matter increased by 43.69% with 5 ppm of Cd and natural bentonite, while durum wheat showed an increase of 88.66% with 10 ppm of Cd and enriched bentonite. In bread wheat, the highest B concentration was obtained with 6% NB at 5 and 10 ppm of Cd, with increases of 15.5%, 39.53%, and 16.56% compared to controls; similar increases were seen in durum wheat. Ca concentrations increased with Cd application in control samples, whereas Mn concentrations decreased with Cd and bentonite treatments. The highest Na concentrations in both wheat varieties were recorded at 6% EB, resulting in significant increases (bread wheat: 2434%-4126%; durum wheat: 2763%-3592%) compared to controls. Nutrient stability for Fe, Cu, K, Mg, P, and Zn varied according to Cd dose and bentonite type. The addition of natural and sodium-enriched bentonite effectively reduced cadmium bioavailability in bread and durum wheat, while promoting increased biomass production. These findings suggest that bentonite amendments have potential applications for enhancing crop yields and ensuring food safety in cadmium-contaminated environments.