SOME LIMITATIONS OF SLUICED FLY ASH AS A LIMING MATERIAL FOR ACIDIC SOILS

Innovative methods are currently being sought to safely utilize and reduce the amount of sluiced fly ash stored in on-site facilities at thermal electric power facilities in Ontario, Canada. The objective of this study was to investigate the possibility of utilizing sluiced fly ash as a liming material on acidic soils. A greenhouse experiment was established to examine the influence of the ash on soil pH values and the yield and chemical composition of corn, soybeans, wheat and alfalfa grown on amended soil. The sluiced ash had an initial pH value of 9.1 (1:1 H2O) and contained an equivalent CACO3content of 11.5 % (+0.2%) based on total content of Ca and Mg in the ash. Fly ash was applied at rates of up to 167 tonnes ha-1 to samples of the surface horizon (0-15 cm) of an acidic clay textured soil found local to the power plant. Application of fly ash increased soil pH values but a high concentration of boron in the added ash limited plant growth. Results indicated that the sluiced ash could be used as a liming material at application rates of up to 110 tonnes ha-1, on acidic, clay textured soils provided boron tolerant crops such as alfalfa were grown. Further research is required to establish the potential for leaching of boron to ground water and to determine the potential for plant uptake of other trace elements such as As and Se. Key Words-fly ash, coal ash, boron toxicity, soil pH, lime requirement, trac