Addition of Vermicompost to Heavy Metal-Contaminated Soil Increases the Ability of Black Oat (Avena strigosa Schreb) Plants to Remove Cd, Cr, and Pb

Abstract

The contamination of soil with heavy metals is a serious agricultural issue. The presence of foods contaminated with heavy metals in the human diet can cause health damages. Metal phytoextraction processes remove soil contaminants through plant absorption; however, plants display different responses to the metal contamination of the soil. Thus, the purposes of this paper were to determine cadmium (Cd), chromium (Cr), and lead (Pb) immobilization in soil mixed with different amounts of stabilized vermicompost (obtained by earthworm composting) and verify if this vermicompost helps in the removal of heavy metal through the phytoextraction technique with black oat (Avena strigosa Schreb cv IAPAR 61) plants. The addition of a high quantity of vermicompost (50, 75, and 100%) to the soil presents similar results to the immobilization of Cd, Cr, and Pb, and a similar trend was observed in lower quantities (0 and 25%) of vermicompost. The addition of vermicompost improves the growth of black oat plants, but only the treatment with 25% of vermicompost showed promising results in the absorption of Cr and Pb, and the treatment with 50% in the absorption of Cd. Finally, we suggest that “IAPAR 61” black oat cultivar is efficient Cd, Cr, and Pb accumulators. However, heavy metal remained mostly in the root, indicating that root-to-shoot translocation was not efficient, hindering its application for phytoremediation strategies.