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Grazing Management Contributions to Net Global Warming Potential: A Long-term Evaluation in the Northern Great Plains

Permanent URL:
http://handle.nal.usda.gov/10113/42860
File:
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Abstract:
The role of grassland ecosystems as net sinks or sources of greenhouse gases (GHGs) is limited by a paucity of information regarding management impacts on the flux of nitrous oxide (N2O) and methane (CH4). Furthermore, no long-term evaluation of net global warming potential (GWP) for grassland ecosystems in the northern Great Plains (NGP) of North America has been reported. Given this need, we sought to determine net GWP for three grazing management systems located within the NGP. Grazing management systems included two native vegetation pastures (moderately grazed pasture [MGP], heavily grazed pasture [HGP]) and a heavily grazed crested wheatgrass [Agropyron desertorum (Fisch. ex. Link) Schult.] pasture (CWP) near Mandan, ND. Factors evaluated for their contribution to GWP included (i) CO2 emissions associated with N fertilizer production and application, (ii) literature-derived estimates of CH4 production for enteric fermentation, (iii) change in soil organic carbon (SOC) over 44 yr using archived soil samples, and (iv) soil–atmosphere N2O and CH4 fluxes over 3 yr using static chamber methodology. Analysis of SOC indicated all pastures to be significant sinks for SOC, with sequestration rates ranging from 0.39 to 0.46 Mg C ha–1 yr–1. All pastures were minor sinks for CH4 (<2.0 kg CH4–C ha–1 yr–1). Greater N inputs within CWP contributed to annual N2O emission nearly threefold greater than HGP and MGP. Due to differences in stocking rate, CH4 production from enteric fermentation was nearly threefold less in MGP than CWP and HGP. When factors contributing to net GWP were summed, HGP and MGP were found to serve as net CO2equiv. sinks, while CWP was a net CO2equiv. source. Values for GWP and GHG intensity, however, indicated net reductions in GHG emissions can be most effectively achieved through moderate stocking rates on native vegetation in the NGP.
Author(s):
Liebig, M.A. , Gross, J.R. , Kronberg, S.L. , Phillips, R.L.
Subject(s):
grasslands , grazing , livestock production , grazing management , global warming , greenhouse gases , nitrous oxide , methane , grazing intensity , pastures , Agropyron desertorum , rangelands , carbon dioxide , nitrogen fertilizers , cattle , soil organic carbon , gas emissions , soil respiration , carbon sequestration , indigenous species , botanical composition , pasture plants , North Dakota
Format:
p. 799-809.
Note:
Includes references
Source:
Journal of environmental quality 2010 May-June, v. 39, no. 3
Language:
English
Year:
2010
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.