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The Center for Native Grasslands Management

Title: Establishment and persistence of legumes in switchgrass (Panicum virgatum) biomass and forage/biomass production systems
Year: 2010
Author(s): Warwick, K., Allen, F., Keyser, P., Bates, G., Tyler, D., Lambdin, P., Harper, C.
Source Title:
Source Type: Proceedings
pages: 37
Original Publication:  
Abstract: Switchgrass is being used as a biofuel feedstock for ethanol production on marginal and crop land. Legumes may be interseeded into switchgrass to improve available N in the soil, reduce fertilizer costs, and enhance switchgrass yield and forage quality. The objective of this research is to develop legume management strategies for switchgrass production systems that are economically and ecologically sustainable for biomass and forage production. Seven cool- and warm-season legumes were examined for four years at the East Tennessee (Knoxville), Plateau (Crossville) and Milan Research and Education Centers. Cool-season legumes included alfalfa Medicago sativa cv “Evermore,” red clover Trifolium pretense cv “Cinnamon Plus,” crimson clover Trifolium incarnatum, common vetch Vicia sativa, and hairy vetch Vicia villosa. The warm-season legumes included Illinois bundleflower Desmanthus illinoensis and partridge pea Chamaechrista fasciculata. Legumes were interseeded into established switchgrass (cv. “Alamo”) and monitored for establishment, self-reseeding, and N contribution as determined by increases in yield. Nitrogen fixation rates of common vetch and hairy vetch were 13.94 kg/ha and 14.84 kg/ha respectively at ETREC for similar-sized plants. Preliminary results indicate alfalfa and Illinois bundleflower are not feasible for establishment in lowland types of switchgrass. Hairy and common vetch, crimson and red clover, and partridge pea look promising for establishment and self-reseeding in established stands of switchgrass. In the forage/biomass system, presence of legumes did not significantly alter ADF (37.4 g/kg % DM), NDF (68.7 g/kg % DM), NEL (0.61 g/kg % DM), TDN (59.1 g/kg % DM), and switchgrass height (29.6 inches). CP (8.72 g/kg % DM) of legume treatments was statistically similar, and red clover CP was not significantly different from 120 lbs N/acre treatment. Total DM yield of red clover, crimson clover, and partridge pea (1.87 tonnes/ha) were not different when compared to 60 lb N treatment, and hairy vetch DM (1.52 tonnes/ha) was not different from the other legume treatments (1.65 tonnes/ha) in 2009. In the biomass system, legume presence did not alter DM yield (2.42 tonnes/ha) in 2009 and switchgrass height (31.8 inches) in 2009-10 from 60 lbs N/ acre treatment.
Publisher: Proceedings of the Seventh Eastern Native Grass Symposium. Knoxville, TN, October 5-8, 2010
Editor(s): C. Harper