AMENDMENT-ASSISTED PHYTOMANAGEMENT OF HEAVY METAL CONTAMINATED AGRICULTURAL SOIL USING MARIGOLD AND VETIVER

Abstract

Industrial activities can introduce multiple heavy metals into agricultural soils, requiring management strategies that improve soil quality while limiting metal exposure. A pot-culture experiment was conducted using industrially contaminated agricultural soil from Perambalur district, Tamil Nadu, to assess various amendment treatments in combination with marigold (Tagetes erecta L.) and vetiver (Chrysopogon zizanioides (L.) Roberty). The experiment was arranged in a two-factor factorial completely randomised design with three replications. Amendment treatments significantly influenced soil properties, biological activity, residual metal concentrations and plant metal uptake. Biochar was the most effective amendment for reducing total soil metal concentrations, achieving reductions of 52.9% for Cr, 54.7% for Pb, 82.4% for Ni and 92.0% for Cd. Vermicompost produced the greatest improvement in soil microbial populations. Root and shoot metal concentrations generally declined under amendment treatments, with vetiver exhibiting greater root accumulation and higher removal efficiency than marigold. Bioconcentration factors remained below unity for all metals, while translocation factors indicated predominant retention of Cr, Pb and Ni in roots, suggesting phytostabilisation as the principal mechanism. Cadmium showed comparatively greater translocation to shoots. The results demonstrated that biochar was the most effective for reducing residual metal concentrations, whereas vermicompost was more effective in restoring soil biological activity. Overall, the biochar-vetiver combination showed the greatest potential for the phytomanagement of industrially contaminated agricultural soils.