Mimicked In-Situ Stabilization of Metals in a Cropped Soil: Bioavailability and Chemical Form of Zinc

Abstract

Agricultural lime, natural zeolite (clinoptilolite), hydroxyapatite, and an iron oxide waste byproduct (Fe-rich, a trademark name of E. I. du Pont de Nemours) were added to an artificially contaminated Appling silt loam soil to stabilize and limit the uptake of Zn by crops. A greenhouse pot study involved spiking the soil with flue dust (FD) at 0, 150, 300, 600, 1200, and 2400 mg of Zn kg - 1 . As much as 40% of the total Zn occurred in an exchangeable form, the form considered most bioavailable to plants, when the pH of the FD-spiked soil was below 6.0. The ameliorants (lime, zeolite, apatite, and Fe-rich) decreased the concentration of the exchangeable form of Zn at each level of FD in soil; however, the largest decrease occurred with the lowest dose. Maize ( Zea mays ), barley ( Hordeum vulgare ), and radish ( Raphanus sativus ) were grown to determine the effects of Zn on the plant growth and its uptake. The addition of ameliorants to soil enhanced the growth and yield of maize and barley, but only Fe-rich enhanced the growth of radish at all FD rates. Lime, zeolite, and apatite significantly reduced the Zn concentration in tissues of the 3-week-old maize, in mature maize tissues (roots, young leaves, old leaves, stems, grain), and in barley. The largest reduction (over 80%) in Zn uptake by all crops was effected by Fe-rich, which is consistent with the greatest reduction in soil-exchangeable Zn by this ameliorant.