Switchgrass Ash Content Response to Harvest Timing and Two Harvest/Storage Methods of a Bioenergy Cropping System in the Great Lakes Region

Abstract

Energy production from the cofiring of plant residue is optimized when ash content of the biomass is minimized. Combustion of bioenergy crop material to produce energy may provide a transition market as cellulosic bioethanol production systems are being developed. A study was conducted to quantify the ash content of switchgrass biomass at a whole-plant scale under four harvest timings and two general harvest/storage methods in the Northern Corn Belt/Great Lakes Region. Results showed that switchgrass ash content was significantly reduced when the biomass was left to overwinter in the field. Although overwintering maximized mineral nutrient retention in the field and produced the best quality biomass for cofiring, it was at the expense of harvest yield. Ash content was largely not significantly influenced by harvest timing during the fall. This suggested increased harvest timing flexibility that was not at the expense of soil nutrient retention. This would allow farmers a wider harvest window to maximize harvest yields. Results showed that harvest/storage method did not have a significant effect on ash content. This further suggested flexibility and adaptability to farmers and the bioethanol industry. This would give the flexibility to choose an appropriate storage method in the context of region-specific conditions without compromising on ash content and the potential for cofiring the biomass or lignocellulosic ethanol production byproducts.