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United States Department of Agriculture

Agricultural Research Service

Research Project: MANAGING DAIRY FARMS FOR ENVIRONMENTAL STEWARDSHIP AND PROFIT Title: Carbon dioxide and water fluxes from switchgrass managed for bioenergy production

Authors
item Skinner, Robert
item Adler, Paul

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 21, 2010
Publication Date: June 18, 2010
Citation: Skinner, R.H., Adler, P.R. 2010. Carbon dioxide and water fluxes from switchgrass managed for bioenergy production. Agriculture, Ecosystems and Environment. 138:257-264.

Interpretive Summary: Switchgrass is an important bioenergy crop with the potential to provide a reliable supply of renewable energy while also removing carbon dioxide from the atmosphere and sequestering it in the soil. The purpose of this study was to determine the carbon sequestration potential of a young switchgrass stand in the northeastern USA. ‘Cave-N-Rock’ switchgrass was established in June, 2004, and carbon dioxide uptake and loss were measured daily from 1 October 2004 to 30 September 2008. Biomass produced each summer was allowed to overwinter in the field and was harvested just before new growth began the next spring. The amount of biomass produced increased over time even though carbon dioxide uptake through photosynthesis was nearly identical each year of the study. Carbon dioxide losses from plant and soil respiration decreased over time as the soil cooled due to increased shading. The switchgrass field accumulated carbon for the first three years, but lost carbon the final year due to the high removal of carbon as harvested biomass. This study suggests that in addition to their primary function as a source of renewable energy, switchgrass bioenergy crops in the northeastern USA can sequester carbon dioxide for the first few years following establishment.

Technical Abstract: Switchgrass (Panicum virgatum L.) is an important bioenergy crop with the potential to provide a reliable supply of renewable energy while also removing CO2 from the atmosphere and sequestering it in the soil. The purpose of this study was to use micrometeorological techniques to quantify CO2 fluxes during the establishment and early production years of a young switchgrass stand in the northeastern USA. ‘Cave-N-Rock’ switchgrass was established in June, 2004, and daily carbon dioxide fluxes were measured from 1 October 2004 to 30 September 2008. Biomass produced each summer was allowed to overwinter in the field and was harvested just before new growth began the next spring. Gross primary productivity (GPP) varied little among years, ranging from -3355 to -3451 g CO2 m-2 yr-1. However, ecosystem respiration (Re) decreased over time from 3339 g CO2 m-2 yr-1 in 2004-2005 to 2661 g CO2 m-2 yr-1 in 2007-2008. The ecosystem generally began to take up CO2 in Mid-May and continued until early-October, and was a net sink during a 98-day period from late-May through early-September. The rest of the year experienced a net loss of CO2 to the atmosphere. Harvested biomass increased each year and was not correlated with GPP. The system was a net CO2 sink for the first three years, but became a source the final year due to increased removal of C as harvested biomass. This study suggests that in addition to their primary function as a source of renewable energy, switchgrass bioenergy crops in the northeastern USA can sequester CO2 for the first few years following establishment.

Last Modified: 12/22/2014
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