© 2014 John Wiley & Sons Ltd
Edited By: Steve Long
Impact Factor: 4.248
ISI Journal Citation Reports © Ranking: 2013: 2/79 (Agronomy); 12/83 (Energy & Fuels)
Online ISSN: 1757-1707
Associated Title(s): Global Change Biology
Carbon fluxes following land conversion
The concentration of carbon in the form of CO2 is rising in the atmosphere and contributing to climate change. Bioenergy delivers CO2 and other greenhouse gas savings when it replaces fossil-based energy that releases large amounts of greenhouse gasses and other pollutants. However, the expansion of agricultural land for bioenergy crop production will require agricultural and natural land to be converted to bioenergy cropland. The land use change associated with expansion of agricultural production for bioenergy crops can result in reduced carbon uptake and/or carbon emissions, and has significant impact on the global carbon budget. The net effect of bioenergy on carbon remains under debate because the carbon savings of fossil fuel replacement and emissions from land use change have yet to be resolved.
Zenone and coauthors quantified carbon exchange during the first year of land conversion to bioenergy crops. Carbon flux (uptake or emissions) was measured at sites that were converted from grasslands or conventional agricultural fields to soybean. The authors found that the extent of emissions is subject to the type of land that is converted for bioenergy crop production. Conversion of grassland to soybean resulted in large carbon losses. Most of this loss occurred after herbicide application when photosynthetic assimilation of carbon ceased and carbon stored in the plants and roots was released. The grassland that was left unaltered continued to gain carbon. In contrast, conversion of conventional agricultural fields to soybean resulted in both carbon loss and gain.
More research is needed to determine if the enhanced CO2 emission of conversion from grassland to soybean continues past the first year and if this loss is negated by the carbon savings of fossil fuel replacement.
Zenone, T., Chen, J., Deal, M. W., Wilske, B., Jasrotia, P., Xu, J., Bhardwaj, A. K., Hamilton, S. K. And Philip Robertson, G. (2011), CO2 fluxes of transitional bioenergy crops: effect of land conversion during the first year of cultivation. GCB Bioenergy. doi: 10.1111/j.1757-1707.2011.01098.x