Application of Coal Fly Ash in Agriculture: A Strategic Perspective

Fly ash is a major waste of coal-power generation and its management is a major environmental and economic challenge, and it will become even more critical with a projected increase in the reliance on coal for power generation. The authors discuss how the unique physicochemical properties of ash can be strategically employed to ameliorate acidity and sodicity, and physical and fertility constraints, in agricultural soils. They show that with careful selection of ash type and methods and rates of application, mutually compatible with the soil and crop type, the often reported phytotoxicity due to high concentrations of certain trace metals can be avoided while maintaining the quality of produce and minimizing risk to the environment. Specific examples are presented to demonstrate where it is economical to use fly ash as a low-cost alternative to certain fertilizers and liming materials on farms. The authors also propose criteria for the selection of ash and for regulatory parameters that would ensure the safe and routine utilization of ash in plant production systems.