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Carl J. Bernacchi Steven E. Hollinger Illinois State Water Survey, Champaign, IL Tilden P. Meyers

Carbon Budget of Mature No-till Corn/Soybean Ecosystem in the North Central Region of the United States. Carl J. Bernacchi Steven E. Hollinger Illinois State Water Survey, Champaign, IL Tilden P. Meyers NOAA Atmospheric Turbulence Diffusion Division, Oak Ridge, Tennessee.

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Carl J. Bernacchi Steven E. Hollinger Illinois State Water Survey, Champaign, IL Tilden P. Meyers

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  1. Carbon Budget of Mature No-till Corn/Soybean Ecosystem in the North Central Region of the United States Carl J. Bernacchi Steven E. Hollinger Illinois State Water Survey, Champaign, IL Tilden P. Meyers NOAA Atmospheric Turbulence Diffusion Division, Oak Ridge, Tennessee

  2. Why Corn and Soybean?

  3. Agricultural Land and C-sequestration • Soils of native prairie were high in Soil Organic Carbon (SOC) • Only ~40% of SOC still remains • Can we increase SOC in the soils of Midwestern agriculture? Donigian, et al. (1994), U.S.EPA, Athens, GA Lal, R., 2004, Science, 304, 1623-1627

  4. Rising Atmospheric CO2 • Controlling atmospheric CO2 is the focus of domestic and international efforts • Improvements in energy • More efficient technology • Improved fuels • Kyoto protocol • Sequester C • Sell C-credits

  5. Focus on No-till • No-till farming has many benefits • Lower costs • Minimize erosion • Better soil moisture • More pest predators, earth worms • Higher SOC (?)

  6. Measuring SOC • Soil measurements and models are traditionally used, but: • Soil measurements are prone to uncertainties over time and space • Models require validation • Augment the wealth of soil measurements / models with a different technique

  7. Using Eddy Covariance to Estimate C Sequestration • Eddy Covariance is a method in which fluxes of CO2, water, and energy can be measured directly • Measurements represent a large area • Measurements are made continuously throughout the year

  8. CO2 fluxes to measure NEE • Net Ecosystem Exchange = net total amount of C transferred between the atmosphere and an ecosystem over a given period of time • Pn= Net photosynthesis • Ra = Autotrophic Respiration • Rh = Heterotrophic Respiration

  9. Bondville Ameriflux Tower

  10. Experimental Method • 6 years of continuous eddy covariance measurements • Corn/soybean rotation agro-ecosystem • 3 years of corn data • 3 years of soybean data • 3 complete rotation cycles • Data collected and back-filled (modeled) as needed

  11. Carbon Sequestration Potential • If the amount of CO2 ENTERING the ecosystem is greater than the amount of CO2 LEAVING the system, then carbon is being sequestered

  12. NEE over Six Years

  13. Local C Fluxes Carbon Sink

  14. Large C-Sink, however… • A large amount of C is removed from the field (yield) • 100% of grain C is consumed annually • Does yield explain all of this sink?

  15. How much C is removed from the no-tilled field? Grain C

  16. Regional C sink assessment • An Intensive Campaign (NACP) has been proposed to do the most comprehensive C budget ever for a certain region of the U.S. • Midwest defined as an ideal location • Relatively few urban areas • Single ecosystem type dominates • A Regional Intensive Campaign requires as much information as possible for each ecosystem type

  17. Regional C Budget • Here in the Midwest, a large amount of C is fixed into grain • The grain is removed from the field • 100% of grain harvest is utilized • Only ~20% of the total grain consumption occurs in the Midwest

  18. Have Three years of NEE data for corn, soybean Precise yield data for these years on the exact field Yield data for each state in the U.S. Grain consumption statistics Need NEE data for all states Assumptions Our field is representative of all fields Assessing the Regional C Budget

  19. Ecosystem Harvest Index (EHI) • Grain carbon (Cgr) was measured via combine yield monitors • Growing season NEE (NEEg) was measured using eddy covariance • EHI was then used as a proxy for NEE over the whole Midwest

  20. Midwestern Carbon Fluxes (MMT)

  21. Regional C sink assessment

  22. Conclusions • Locally, Midwestern corn/soybean ecosystem represents a large C-sink to the atmosphere • Globally, most of the C-sink is found in grain • Accounting for all Grain C, ecosystem is still a sink (C sequestration potential exists)

  23. Conclusions (cont’) • Regionally, a huge C sink exists • Most C stored in grain is consumed out of the region • Over 81 MMT of C is fixed in this region

  24. Acknowledgements • Office of Science (BER), U.S. Department of Energy, Grant No DE-FG02-03ER63685 • National Oceanic and Atmospheric Association (NOAA) • John Reifsteck

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