EVALUATION OF FLY-ASH AS A SOIL AMENDMENT FOR THE ATLANTIC COASTAL-PLAIN .1. SOIL HYDRAULIC-PROPERTIES AND ELEMENTAL LEACHING

A major limitation to crop yields in the Atlantic Coastal Plain is drought stress caused by the low moisture-holding capacities of the coarse-textured soils common to the area. Because coal fly ash is comprised primarily of silt and clay-sized particles, it has the potential, if applied at high enough rates, to permanently change soil texture and increase moisture holding capacity. A series of soil column studies were conducted to evaluate the effects of high rates of fly ash on soil hydraulic properties and elemental leaching of trace metals and boron, Fly ash from two Delaware power plants (EM=Edgemoor and IR=Indian River) was incorporated in a Hammonton loamy sand (fine-loamy, siliceous, mesic, Typic Hapludults) at six rates (0, 5, 10, 20, 30, and 40%, by weight). The effect of fly ash on soil moisture holding capacity, hydraulic conductivity, and wetting front velocity was determined. Leachates from columns amended with 30% fly ash were analyzed for B, Cd, Ni, Pb, Cu, and Zn. Soil moisture holding capacity was increased from 12% in the soil alone to 25% in the soil amended with 30% fly ash. Boron and soluble salts leached rapidly from ash amended soils while only trace quantities of Cd, Ni, Pb, Cu, and Zn were detected in column leachates.