Verma, Shashi. B. (Univ. of NE-Lincoln, School of Nat Resources, 243 LW, Chase Hall, Lincoln, NE, 68583-0728; Phone: 402- 472-6702; Fax: 402- 472-6614; Email:


Annual CO2 Exchange in Irrigated and Rainfed Maize-Based Agro ecosystems


S.B.Verma *, Andrew E. Suyker, George G. Burba, Timothy J. Arkebauer, Daniel T. Walters, Achim Dobermann, Kenneth G. Cassman, Brigid Amos, Haishun Yang, Kenneth G. Hubbard, Anatoly A. Gitelson, Elizabeth A. Walter-Shea, Daniel Ginting


Carbon dioxide exchange was quantified in the dominant maize-soybean cropping systems of the USA Corn Belt employing year-round tower eddy covariance flux systems during 2001-2004.  Flux tower measurements were made in production-scale fields for three cropping systems:  (a) irrigated continuous maize, (b) irrigated maize-soybean rotation, and (c) rainfed maize-soybean rotation.  We will present results on net ecosystem exchange (NEE) for the initial three years of this study to address the following questions:  (1) how does the seasonal and annual carbon dioxide exchange of maize compare with that of soybean?  (2) What is the impact of irrigation, versus dryland farming, on the carbon dioxide exchange of these crops? (3) How does the annual carbon dioxide exchange of continuous maize system compare with a maize-soybean rotation?  Crop and soil management in each of these systems followed progressive, best management practices and our results provide relevant information on C sequestration of these systems.