Use of Fly Ash as Soil Amendment for Biofuel Feedstock Production with Concomitant Disposal of Waste Accumulations

Increasingly higher costs of disposal of fly ash (FA) on the one hand, and on the other, the current focus on bioenergy offer opportunities for using FA as soil amendment for producing biofuel feedstock while cleaning up accumulations of the product. Greenhouse pot experiments were conducted in a silt loam soil amended with 0%, 2.5% and 20% FA to determine boundary shoot and root biomass productivity by the cellulosic herbaceous perennials (CHPs) switchgrass (SG), eastern gamagrass (GG) and big bluestem (BB) grown at pH=4.5 and 6.5. After three months of growth at pH=4.5, shoot biomass productions was generally in the order SG>GG>BB. Root biomass was slightly different and it was in the order SG=GG>BB. Soil amendment with 2.5% FA did not affect biomass production either CHP; however, biomass production at 20% FA amendment declined in all cases. Results for SG and BB only evaluated at pH 6.5 were similar to those at pH 4.5. Needs were identified to define optimum levels of FA amendment to add to soil and combinations of FA and organic amendment that could enhance simultaneous utilization of FA and biofuel feedstock production.