Fly Ash and Lime Amendment of Acidic Coal Spoil to Aid Revegetation

Abstract

AbstractA greenhouse study was conducted to evaluate the effect of fly ash (0, 10, 20, 30, and 40 g kg−1 of spoil) and agricultural lime (0, 10, 20, 40, and 80 g kg−1 of spoil) on ameliorating the low pH of acidic coal mine spoils. Topsoil depths of 0, 10, and 20 cm placed over the spoil were also evaluated. Two crops of barley (Hordeum vulgare L.) were grown to evaluate effects of the amendments and topsoil on aboveground plant biomass, root biomass and distribution, and element content of the vegetation. All levels of lime and fly ash significantly increased the spoil pH, aboveground plant biomass, and root biomass. Topsoil placement over the spoil also generally increased plant biomass. Root growth in untreated spoil was limited to the depth of topsoil. However, when the spoil was amended with either fly ash or lime root growth occurred throughout the material. Fly ash and lime did not cause elemental toxicities to the plants, except for B. Although visual B toxicity symptoms and elevated levels of plant B were evident, no reduction in plant biomass occurred. The results indicate that fly ash is a feasible alternative to lime for treating acidic coal spoils in the region.