Establishment and Persistence of Legumes in Switchgrass

1. Establishment and Persistence of Legumes in Switchgrass Biomass and Forage/Biomass Production Systems Hairy Vetch • K. Warwick1, F. Allen1, P. Keyser2, G. Bates1, D. Tyler3, P. Lambdin4, C. Harper2 • Department of Plant Sciences (2) Department of Forestry, Wildlife, & Fisheries • (3)Biosystems Engineering and Soil Science (4)Entomology and Plant Pathology • University of Tennessee Crimson Clover Partridge Pea Abstract ExpTwo:Two-Cut Forage (Summer)/ Biomass (Fall) Harvest ETREC & PREC Switchgrass is being used as a biofuel feedstock for ethanol production on marginal, as well as, 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. A total of seven cool and warm-season legumes were examined for two years at the research and education centers East Tennessee (Knoxville), Plateau (Crossville) and Milan. The cool-season legumes were 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 in the study were Illinois bundle flower, Desmanthus illinoensis; and partridge pea, Chamaechrista fasciculata. The legumes were interseeded into established 2 y old switchgrass (cv. ‘Alamo’) and monitored for establishment, self-reseeding, and N contribution as determined by increases in yield. • Nitrogen Treatments • 67 + 67 kg/ha N • 67 kg/ha N • 0 kg/ha N (control) • Legume Treatments • Same as Experiment One Exp Three:N Fixation in Common & Hairy Vetch ETREC • Quantify Nitrogen Fixation Rates • N2 fixed= (Vetch N) – (Wheat N) • Plant N= (Plant DM) x (%N) • 100 • (Danso, 1995; Peoples et al., 2009) • Common Vetch • Hairy Vetch • 0+0 kg/ha N • Wheat- Control plant Results Figure 5. Yield of 1st and 2nd cut in the forage/biomass harvest system across both locations (ETREC, PREC) for 2009. There was no significant difference among legume treatments. Summary • ALF and IBF germinated but did not persist in competition with • switchgrass (Fig. 1) • 0 N vs 67 N treatments across locations, years, and experiments • were not significantly different (Fig. 2, 3, & 5) • In the forage/biomass system, presence of legumes did not • significantly alter forage quality among legumes treatments. Data • not shown. • Presence of legumes in 1-cut biomass system did not significantly • alter SG yield from 67 N treatments except for RC (Fig. 2). • In the forage system, there were no significant differences in SG • yields among the legume treatments and 67 kg ha-1 N when • averaged across both locations for two years (Fig. 3). • In the forage/biomass system, total SG yield (forage + biomass) • did not differ among legume treatments; however , HV and PP • treatments were significantly lower than 67 and 135 kg ha-1 N when • averaged across two locations in 2009 (Fig. 5). • Insufficient time to determine reseeding and persistence of • crimson and red clover, hairy vetch, and partridge pea in lowland • switchgrass types such as ‘Alamo’. • N fixation rates were similar for common and hairy vetch (2.1 & • 2.2 kg ha-1, respectively) based on seeding rates and plant • populations of this study. • Given above N fixations rates and plant densities, we estimate • that seeding rates of common and hairy vetch would need to be • 14.5 & 13.6 kg ha-1, respectively to achieve 33.5 kg ha-1 N fixation • rates. Objectives Figure 1. Legume count and plant heights across locations. Switchgrass height was not significantly different among treatments. Heights and counts taken on 13May09 & 24May10 at ETREC, 14May09 &25May10 at PREC, and 19May2009-10 at RECM. • Identify selected cool- & warm-season legumes that can be grown with switchgrass (SG) for biomass/forage systems • To determine switchgrass/legume forage quality for the two-cut integrated forage/ biomass approach. • Determine nitrogen contribution of common and hairy vetch grown with switchgrass and its affect on yield. Materials/Methods • Exp Design: Randomized Complete Block • Replications: 3 per location • Locations: East TN Research & Education Center (ETREC) • Plateau Research & Education Center (PREC) Research and Education Center at Milan (RECM) • See Fig. 4 Figure 2. Yield for single cut in biomass harvest system across all locations (ETREC, PREC, RECM) for 2009. There is no significant difference among legume treatments. • N applications: • 1-cut system: Spring applied at SG green-up • 2-cut system: Spring applied at green-up & • Approx. 2wks after 1st cut Characteristics Measured Future Research • Stand densities (Vogel and Masters, 2001) & plant hts on count dates • Forage yields and quality (2-cut system) 2009-10 • Biomass yields (1&2-cut systems) 2009 • N fixation rates of Common and Hairy Vetch • (Danso, 1995; Peoples et al., 2009) • New study of 1x,1.5x, 2x of arrowleaf, ladino, and red clover; • hairy vetch, and partridge pea has been initiated in 2010. Literature Cited • Danso, S. K. A. 1995. Assessment of biological nitrogen fixation. • Fertility Research 42: 33–41. • Peoples, M.B., M.J. Unkovich, and D.F. Herridge. 2009. Measuring • symbiotic nitrogen fixation by legumes. In D.W. Emerich and H.B. • Krishnan (Ed.) Nitrogen Fixation in Crop Production. Agronomy • Monograph 52:125-170. • Vogel K.P. and R.A. Masters. 2001. Frequency grid–a simple tool for • measuring grassland establishment. Journal of Range Management • 54: 653–655. Figure 3. Yield for 1st cut in the forage/biomass harvest system across both locations (ETREC, PREC) for 2009-10. There was no significant difference among legume and 67 kg N treatments. Experiment Descriptions Exp One: One Cut (Biomass) Harvest (Fall) ETREC, PREC, RECM • Legume Treatments • Alfalfa (ALF) (13.46 kg seed ha-1) • Crimson Clover (CC) (6.73 kg seed ha-1 ) • Hairy Vetch (HV) (6.73 kg seed ha-1 ) • Illinois Bundle Flower (IBF) • (8.97 kg seed ha-1 ) • Red Clover (RC) (8.97 kg seed ha-1 ) • Partridge Pea (PP) (13.46 kg seed ha -1) Nitrogen Treatments • 60 lbs/ac N • 0 lbs/ac N (control) • Alf + 67 kg/ha N • RC + 67 kg/ha N • CC + 67 kg/ha N* • HV + 67 kg/ha N* • IBF + 67 kg/ha N* • PP + 67 kg/ha N* • 135 kg/ha N* This project funded by: Figure 4. Tennessee research and education center. Indicated centers read left to right are RECM, PREC, ETREC. http://www.taes.utk.edu/centers/ *Treatments only at RECM