FORAGE AND BIOMASS DUAL-PURPOSE HARVEST SYSTEM USING NATIVE WARM-SEASON GRASSES

There has been increasing interest in utilizing native warm-season grasses (NWSGs), especially switchgrass, as a biomass feedstock for cellulosic ethanol production. Millions of hectares of crop and pasture in the mid-South are forecast to potentially be planted with switchgrass for biomass feedstock production. This could have a substantial impact on the region’s cattle industry, reducing forage production hectares. This study was conducted to determine the effect of early season harvest timing on forage and biomass of NWSGs designed for use in cellulosic ethanol production. The over-all hypothesis was to determine if an early forage harvest can be included in a dual-purpose system along with a fall biomass harvest for cellulosic ethanol production without significantly reducing fall biomass yields. The NWSGs used in this study were switchgrass (Panicum virgatum L.) monoculture (SG), SG/big bluestem (Sorghastrum nutans L.) /indiangrass (Andropogon gerardii V.) mixture (SGBBIG), and big bluestem/indiangrass mixture (BBIG). These NWSGs were harvested at fall dormancy for biomass only (FD), early boot plus FD (EBFD), and early seedhead plus FD (ESHFD). Therefore, the objectives of this study were to determine the effect (i) early-season harvest timing on fall biomass yield, (ii) early season forage harvests yield and quality, and (iii) species mixtures on biomass quality in a dual-purpose system. Results from this study should provide information about dual-purpose systems using NWSGs in monoculture and mixtures for both forage and biomass.