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ARS Home » Pacific West Area » Pullman, Washington » Northwest Sustainable Agroecosystems Research » Research » Publications at this Location » Publication #263321
Title: Response of Alamo switchgrass tissue chemistry and biomass to nitrogen fertilization in West Tennessee, USA

Author
item GARTEN, C - Oak Ridge National Laboratory
item BRICE, D - Oak Ridge National Laboratory
item CASTRO, H - Oak Ridge National Laboratory
item GRAHAM, R - Oak Ridge National Laboratory
item MAYES, M - Oak Ridge National Laboratory
item PHILLIPS, J - Oak Ridge National Laboratory
item POST, W - Oak Ridge National Laboratory
item SCHADT, C - Oak Ridge National Laboratory
item WULLSCHLEGER, S - Oak Ridge National Laboratory
item TYLER, D - University Of Tennessee
item JARDINE, P - University Of Tennessee
item JASTROW, J - Argonne National Laboratory
item MATAMALA, R - Argonne National Laboratory
item MILLER, R - Argonne National Laboratory
item MORAN, K - Argonne National Laboratory
item VUGTEVEEN, T - Argonne National Laboratory
item IZAURRALDE, R - Global Change Research Institute
item THOMSON, A - Global Change Research Institute
item WEST, T - Global Change Research Institute
item AMONETTE, J - Pacific Northwest National Laboratory
item BAILEY, V - Pacific Northwest National Laboratory
item METTING, F - Pacific Northwest National Laboratory
item Smith, Jeffrey

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2010
Publication Date: 1/7/2011
Citation: Garten, C.T., Brice, D.J., Castro, H.F., Graham, R.L., Mayes, M.A., Phillips, J.R., Post, W.M., Schadt, C.W., Wullschleger, S.D., Tyler, D.D., Jardine, P.M., Jastrow, J.D., Matamala, R., Miller, R.M., Moran, K.K., Vugteveen, T., Izaurralde, R.C., Thomson, A.M., West, T.O., Amonette, J.E., Bailey, V.L., Metting, F.B., Smith, J.L. 2011. Response of Alamo switchgrass tissue chemistry and biomass to nitrogen fertilization in West Tennessee, USA. Agriculture, Ecosystems and Environment. 140:289-297. doi:10.1016/j.agee.2010.12.016.

Interpretive Summary: Switchgrass is a perennial, warm-season grass that has been identified as a potential biofuel feedstock throughout a large part of North America. The purpose of this research was to examine above- and belowground responses to nitrogen fertilization in 5-year old “Alamo” switchgrass. Nitrogen fertilization impacted both above- and belowground biomass and tissue chemistry in a way that potentially affects soil carbon cycle processes; high fertilization could accelerate root decomposition and reduce soil carbon. The data from these experiments will be especially useful for scientists and producers of switchgrass to determine the nitrogen needed for high yield production of switchgrass for biofuel feedstock.

Technical Abstract: The purpose of this research was to examine above- and belowground responses to nitrogen fertilization in 5-year old “Alamo” switchgrass (Panicum virgatum). A fertilizer experiment included spring and fall sampling of switchgrass grown under annual applications of 0, 67, and 202 kg N ha-1. Nitrogen fertilization impacted both above- and belowground biomass and tissue chemistry in a way that potentially affects soil carbon cycle processes. Our first hypothesis, that nitrogen fertilization would significantly alter plant biomass or carbon allocation, was only partly supported because even though end-of-growing season mean (±SE) root:shoot ratios declined significantly (P =0.05) with fertilization (2.16 ±0.08, 2.02 ±0.18, and 0.88 ±0.14, respectively, at 0, 67, and 202 kg N ha-1) both above- and belowground biomass tended to increase in response to nitrogen fertilization. Results supported a second hypothesis that nitrogen fertilization would decrease root C:N ratios, primarily as a consequence of increasing tissue nitrogen concentrations. Nitrogen supply through fertilization appeared to most closely matched by plant nitrogen demand at the lowest fertilizer treatment where calculated annual nitrogen uptake was 6.6 g N m-2. Because of changes in root C:N ratios, high rates of nitrogen fertilization (>67 kg N ha-1) could accelerate root decomposition and result in reduced soil carbon inputs beneath switchgrass; however, this response depends on the interplay between processes leading to protection of soil carbon inputs and changing root decomposition rates as a function of changes in tissue chemistry.