Comment on “Carbon budget of mature no-till ecosystem in North Central Region of the United States”

Authors

Achim R. Dobermann, University of Nebraska-LincolnFollow
Daniel T. Walters, University of Nebraska-LincolnFollow
John M. Baker, University of Minnesota, St. Paul, MNFollow

Document Type

Article

Date of this Version

March 2006

Comments

Published in Agricultural and Forest Meteorology 136 (2006) 83–84.

Abstract

Following a 6-year study of net ecosystem exchange of carbon (NEE) in a maize–soybean system, Hollinger et al. (2005) concluded that the system was a net sink of 90 g C m^-2 year^-1. This estimate was erroneous because a wrong equation for computing grain carbon removal (Eq. 1) was used and because the authors computed average annual values for each of the two crops (average C gain under maize: 184 g C m^-2; average C loss under soybean: -94 g C m^-2), then added them together, as if both crops were present each year. Hollinger et al. (2006) have recently corrected those calculation errors, now suggesting that (1) maize acted as a C-sink of 184 g C m^-2, (2) soybean was a C-source of 124 g C m^-2, and (3) the system was a net sink of 30 g C m^-2 year^-1. Although we agree with the corrections of the major calculation errors, we disagree with the authors’ conclusions about the carbon sequestration potential of the maize–soybean rotation.