ABSTRACT
Plants growing directly in coal ash, without a cover layer of soil, might contain excessive concentrations of potentially toxic metals. A field study was initiated to evaluate metal contents of revegetated plants in coal ash and to determine the capabilities of the NH4HCO3-DTPA soil test to predict plant-availability of metals. A revegetation site was established in eastern Kansas near a coal-fired power plant which uses high-S eastern coal and low-S western coal. Plots were constructed with 90 cm of ash mixtures containing eastern scrubber sludge plus eastern bottom ash, western fly ash plus eastern scrubber sludge, or western bottom ash. Sorghum and soybean were seeded directly into the ash. Selected plots were amended with 5% composted manure or 5% composted manure plus 1% soil. Unamended ash consistently supported very poor yields. Addition of manure greatly increased plant dry matter, but there was no advantage to adding soil to the amended plots. Soybean plants in all treatments showed symptoms of severe B toxicity, but sorghum growing in amended ash exhibited no symptoms of stress. High concentrations of B, Mo, Zn, and Cd were observed in at least some treatments. All other metals were within normal concentration ranges. Metal concentrations extracted by the NH4HCO3-DTPA soil test were correlated with the concentrations of metals in plants (p<0.05) for nine elements, including Zn, Cu, Mo, Cd, B, and Pb.
