Tuesday, November 6, 2007
142-8
Field Performance and Biogasification of Switchgrass.
Tawainga Katsvairo and Pratap Pullammanappallil. University of Florida, 155 Research Rd., Quincy, FL 32351
Switchgrass can be used as a feedstock for biofuels for producing either ethanol or methane. While switchgrass is a potentially important bioenergy crop, little is known on its performance in Florida . Florida has an ideal climate of long growing season and warm temperatures, furthermore switchgrass can overwinter in Florida , leaching out nutrients. We determined yield and nutrient concentration in spring of 2006 for four switchgrass varieties, Alamo, DeFuniak, Miami , Stuart and Wabasso. The switchgrass had been grown without any inputs such as fertilizer and mowed for 8 years prior to the 2006 harvest. Dry matter yield for the crop, grown with no input ranged from 13 to 30 Mg ha-1, with Stuart yielding the greatest. N concentration ranged from 3.88 to 5.0 g kg-1, P from 0.29 to 0.54 g kg-1 and K ranged from 0.94 to 1.35 g kg-1. Even greater yields would be expected with Fertilization. Coarsely shredded (particle size greater than 3”), dry switchgrass was biogasified in a high-solids, single stage anaerobic digester. Preliminary experiments produced ~ 180 L of CH4 at STP/ kg dry matter within two weeks. This yield is comparable to that obtained from other energy crops and organic residues (and wastes).