Submitted to: International Ash Utilization Symposium
Publication Type: Proceedings
Publication Acceptance Date: 11/18/1999
Publication Date: N/A
Technical Abstract: Appalachian pastures and woodlands are often acidic and low in Ca and Mg. Limestone supplies Ca and insolubilizes toxic Al and Mn, but incorporation below the surface 15-cm layer is impractical. Addition of coal combustion scrubber products rich in CaSO4 allows Ca leaching into subsurface layers to reduce limitations to root growth. The top 15 cm of columns of a Typic Hapludult (Lily) loam soil were treated with dolomitic limestone (aglime), flue gas desulfurization (FGD) gypsum, aglime + FGD gypsum, FGD gypsum + 6% Mg(OH)2, and a fluidized bed combustion residue (FBC). The 105 cm tall columns were leached with the equivalent of approximately one year of rainfall. From 11% to 16% of the Ca in the gypsum treatments leached out of the columns. In the Aglime + FGD gypsum treatment 38% of the total Mg, an important plant nutrient, was lost as leachate. Percentage retention of Mg of the FGD gypsum + 6% Mg(OH)2 treatment was even lower. Soil Al decreased, partly due to Al leaching from the column. Leachate Al concentrations reached 11 mg/L. This study indicates that applying gypsum effectively increases subsurface Ca levels, and concomitant application of dolomitic limestone helps maintain Mg concentrations at levels adequate for plant growth.