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

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.