Corn and soil response to application of ash generated from gasified alfalfa stems

Electricity generation from biomass is becoming a more environmentally soun d option than nonrenewable fuels. Pilot studies have demonstrated that alfa lfa (Medicago sativa L,) stems are a suitable feedstock for energy generati on via gasification, Developing beneficial uses for ash produced as a bypro duct will enhance the economic viability of bioenergy, A greenhouse study w as conducted to evaluate the potential use of alfalfa ash as a fertilizer a nd/or liming agent using corn (Zea mays L.). Two soils, a Hubbard sand (low pH, low K, and high. P), and a Barnes clay loam (high pH, high K, and low P) were used. Treatments included a control, K and/or P fertilizers, and si x ash rates ranging from 0.2 to 6.4 g kg(-1) (450 to 15,000 kg ha(-1)). Ash application significantly increased K and decreased Mg concentrations in c orn. However, neither plant P nor trace elements were affected by ash appli cation. Elemental uptake by plants paralleled their respective concentratio ns. Soil pH increased linearly in the Hubbard soil with ash but was not aff ected in the Barnes soil. Ash application significantly increased salinity, Cl, extractable P, exchangeable K, Ca, Mg, and Na in both soils. Ash from gasified alfalfa stems seems to be a potential source of K and a potential liming agent for acid soils. When used at agronomically reasonable rates, a lfalfa ash did not pose any risk of excessive accumulation of metals rested in soil or plants.