Bernacchi, Carl (Illinois State Water Survey, 2204 Griffith Drive, Champaign, IL, 61820; Phone: 217-333-8048; Fax: 217-244-0220; Email: bernacch@uiuc.edu)

Carbon Budget of Mature No-till Ecosystem in North Central Region of the United States

C. J. Bernacchi*, S.G. Hollinger, T. Meyers

Continuous measurements of carbon flux data from 1997 through 2002 were used to evaluate the carbon budget for a no-till maize (Zea mays L.) and soybean (Glycine max (L.) Merr.) rotation agricultural ecosystem using the eddy covariance technique. These measurements were used to determine the Net Ecosystem Exchange of carbon (NEE) at the local and regional scales.  Results show that on the local and regional scales, the maize/soybean no-till ecosystem is a carbon sink; however, corn is the dominant sink in the ecosystem. Locally, the sink is mostly explained by the carbon stored in the grain, which is removed from the field during harvest. On a regional scale, the sink is proportionally lower than that of the local scale, which is attributed to regional consumption of the grain. Nearly 100% of both maize and soybean yields are consumed annually, e.g., all carbon stored in grain is consumed somewhere in the world. The grain consumption results in a much lower carbon sink, but the results imply that long-term carbon-sequestration potential of this no-till ecosystem exists.