Biofuels from crop residue can reduce soil carbon and increase CO₂ emissions

Authors

Adam J. Liska, University of Nebraska-LincolnFollow
Haishun Yang, University of Nebraska - LincolnFollow
Maribeth Milner, University of Nebraska-LincolnFollow
Steve Goddard, University of Nebraska-LincolnFollow
Humberto Blanco-Canqui, University of Nebraska-LincolnFollow
Matthew P. Pelton, University of Nebraska-Lincoln
Xiao X. Fang, University of Nebraska-Lincoln
Haitao Zhu, University of Nebraska - LincolnFollow
Andrew E. Suyker, University of Nebraska-LincolnFollow

Date of this Version

4-2014

Citation

Published in Nature Climate Change 4 (May 2014), pp. 398–401; doi: 10.1038/NCLIMATE2187 http://www.nature.com/natureclimatechange

Comments

Copyright © 2014 Macmillan Publishers Limited. Used by permission.

Abstract

Removal of corn residue for biofuels can decrease soil organic carbon(SOC) and increase CO₂ emissions because residue C in biofuels is oxidized to CO₂ at a faster rate than when added to soil. Net CO2 emissions from residue removal are not adequately characterized in biofuel life cycle assessment (LCA). Here we used a model to estimate CO₂ emissions from corn residue removal across the US Corn Belt at 580 million geospatial cells. To test the SOC model, we compared estimated daily CO₂ emissions from corn residue and soil with CO₂ emissions measured using eddy covariance, with 12% average error over nine years. The model estimated residue removal of 6 Mg per ha^–1 yr^–1 over five to ten years could decrease regional net SOC by an average of 0.47–0.66 Mg C ha^–1 yr^–1. These emissions add an average of 50–70 g CO₂ per megajoule of biofuel (range 30–90) and are insensitive to the fraction of residue removed. Unless lost C is replaced, life cycle emissions will probably exceed the US legislative mandate of 60% reduction in greenhouse gas (GHG) emissions compared with gasoline.

Supplementary information is attached below as an additional (pdf) file.