Fertility Evaluation of Limed Brazilian Soil Polluted with Scrap Metal Residue

Abstract

The aim of this work was to characterize the main inorganic contaminants and evaluate the effect of lime addition, combined with soil dilution with uncontaminated soil, as a strategy for mitigation of these contaminants present in a soil polluted with auto scrap. The experiment was performed in a greenhouse at Campinas (São Paulo State, Brazil) in plastic pots (3 dm−3). Five soil mixtures, obtained by mixing an uncontaminated soil sample with contaminated soil (0, 25, 50, 75, and 100% contaminated soil), were evaluated for soil fertility, availability of inorganic contaminants, and corn development. In addition to the expected changes in soil chemistry due to the addition of lime, only the availability of Fe and Mn in the soil mixtures was affected, while the available contents of Cu, Zn, Cd, Cr, Ni, and Pb increased to some extent in the soil mixtures with higher proportion of contaminated soil. Liming of 10 t ha−1followed by soil dilution at any proportion studied was not successful for mitigation of the inorganic contaminants to a desired level of soil fertility, as demonstrated by the available amounts extracted by the DTPA method (Zn, Pb, Cu, Ni, Cr, Cd) and hot water (B) still present in the soil. This fact was also proved by the phytotoxicity observed and caused by high amounts of B and Zn accumulating in the plant tissue.