Effect of Organic Amendments on Micronutrients (Fe, Zn and Cu) Uptake by Tomato (<i>Lycopersicon Esculentum Miller</i>) Plant

This study explores the effectiveness of organic amendments animal manure, compost, and vermicompost in reducing the accumulation of trace heavy metals (Fe, Zn, and Cu) in tomatoes grown in contaminated soil collected from the Akaki River area. The experiment was conducted over two consecutive growing seasons (2019/2020 and 2020/2021), with organic materials applied at concentrations of 3%, 6%, and 9%. The results demonstrated that all three organic amendments significantly reduced heavy metal concentrations in both the soil and tomato fruits compared to the untreated control. Among the amendments, vermicompost proved to be the most effective in lowering the uptake of heavy metals, followed by compost and then animal manure. Specifically, the application of 9% vermicompost decreased iron concentrations in tomato fruits from 461.67 mg/kg to 196.82 mg/kg, zinc from 5.75 mg/kg to 3.30 mg/kg, and copper from 12.17 mg/kg to 4.27 mg/kg in the 2019 season. Similar trends were observed in the 2020 season, confirming the consistency of the treatment effects. These reductions brought metal levels closer to or within the permissible limits established by FAO/WHO guidelines for safe food consumption. The study highlights the potential of organic amendments particularly vermicompost as an effective and sustainable strategy for mitigating heavy metal contamination in agricultural soils. By enhancing soil quality and reducing metal bioavailability, these organic treatments contribute to improved crop safety and promote environmentally sound agricultural practices, especially in areas affected by industrial pollution and wastewater irrigation.