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The Center for Native Grasslands Management




Title: Managing switchgrass as biofuels feedstock
Year: 2000
Author(s): Parrish, D. J., Wolf, D. D., Peterson, P. R., Daniels, W. L.
Source Title: Proceedings of the 2nd Eastern Native Grass Symposium
Source Type: Proceedings
pages: 236
Original Publication:  
Abstract: Switchgrass, a native perennial, is being studied as a model species for a system in which herbaceous plants would be grown for conversion into liquid fuels or for direct combustion. We are in the eighth year of an eight location, five state (KY, NC, TN, VA, WV) trial with six varieties or lines of switchgrass. The plants are receiving varying rates of N and two different cutting managements --once or twice per year. The first harvest of the two-cut management comes in late June, and the fall harvest with either one- or two-cut management comes near the end of October. These studies have focused on biomass yields and nutrients removed in the biomass. Parallel studies have looked at C and N fluxes within the biomass. The findings to date indicate the switchgrass productivity varies greatly with location and variety, and to a lesser degree with N and cutting management. The lowland varieties used (’Alamo’ and ’Kanlow’ and two breeder’s lines) showed little or no yield increase with two cuttings. The two upland types (’Indian’ and ’Shelter’) yielded 20 to 30% more when they were cut twice. With that boost in yield, they approached the lowland types in productivity. Parallel studies detected standing biomass declines of about 10% between August and late October. During that interval, tissue N concentrations decline in the aboveground portions of the plants and increase in belowground portions. It appears that the plants translocate significant amounts of biomass below ground at the end of the growing season. This would appear to be a strategy that conserves N and promotes growth in the following season. Cutting twice (with one cut taken in June, when the plants are relatively rich in N) appears to deplete the plants’ N reserves. A response to N fertilization was evident primarily when the plots were harvested twice a year, i.e., there was no yield benefit of adding 100 kg N/ha to plots that were harvested only after the end of the growing season. The parallel studies also suggest that switchgrass has the potential to sequester significant amounts of C within its roots and the soil.
Publisher: Agricultural Research Service and Natural Resource Conservation Service, Beltsville, MD
Editor(s): J. R. Ritchie
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