Zinc shields against copper phytotoxicity in a contaminated soil.

While zinc protects plants from copper in hydroponics, its behavior in soil remains unclear. We investigated the potential of zinc sulfate to protect ryegrass from copper toxicity in contaminated soil. Twelve soil treatments combined varying levels of copper oxide (CuO) and zinc sulfate (ZnSO ₄ ). Increasing CuO significantly stunted ryegrass, but adding ZnSO ₄ mitigated the effects at each CuO level. ZnSO ₄ had no effect in unpolluted conditions. These results, supported by the Terrestrial Biotic Ligand Model, indicate that zinc competes with copper for binding sites, reducing copper uptake by ryegrass and mitigating its toxicity. Application of zinc sulfate to copper-contaminated soils appears promising for ryegrass growth, although field studies are critical to confirm real-world efficacy.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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