SEWAGE-SLUDGE LAND APPLICATION PROGRAM IN WEST-VIRGINIA

Municipal sewage sludge can be used as a fertilizer for crops but may also introduce undesirable metals into the food chain, especially when used on acid minesoils. In this study, sewage sludge from Morgantown, WV was surface applied to two acid minesoils and a neutral undisturbed soil to evaluate sludge application rates on forage production, nutrient loadings, and on heavy metal accumulation in soils and vegetation. On a reclaimed surface mine at Westover, 0, 15, 31, and 64 dry Mg aha-1 of sewage sludge were applied in March 1986 and monitored annually through 1989. These rates of sludge were three to 12 times greater than recommended N rates for pasture on this site. Grass biomass increased and legume biomass decreased with increased sludge application. Weed biomass was increased only during 1986. Minesoil pH was not significantly affected while soil organic carbon four years after treatment increased from 15 to 22 g kg-1 with sludge. Minesoil DTPA-extractable Cu, Zn, and heavy metal concentrations also increased with sludge application. Sludge was also applied at up to 27.6 Mg ha-1 at Dellslow (reclaimed surface mine) and Pentress (undisturbed). Vegetative production was 1.5 to 2.8 times greater on sludge-treated versus control plots during 1989 and 1990 at both sites, but soil pH was unaffected by sludge treatment. No significant differences were found for DTPA-extractable Cu, Pb, and Zn in the upper 15 cm (6 in) of soil. Forage tissue analyses revealed greater crude protein, but no differences in Cu, Pb, and Zn concentrations in treated compared to control plants. Guidelines for land application of sludge in West Virginia have been refined accordingly, and from 1988 to 1990, land applied sludge doubled from 4,150 to 8,520 Mg (4,570 to 9,430 tons).