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Grazing management contributions to net global warming potential: a long-term evaluation in the Northern Great Plains.

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 (N(2)O) and methane (CH(4)). 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) CO(2) emissions associated with N fertilizer production and application, (ii) literature-derived estimates of CH(4) production for enteric fermentation, (iii) change in soil organic carbon (SOC) over 44 yr using archived soil samples, and (iv) soil-atmosphere N(2)O and CH(4) 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 CH(4) (<2.0 kg CH(4)-C ha(-1) yr(-1)). Greater N inputs within CWP contributed to annual N(2)O emission nearly threefold greater than HGP and MGP. Due to differences in stocking rate, CH(4) 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 CO(2equiv.) sinks, while CWP was a net CO(2equiv.) 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.

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  • Authors+Show Affiliations

    ,

    USDA-ARS, Northern Great Plains Research Lab., Mandan, ND 58554-0459, USA. mark.liebig@ars.usda.gov

    , , ,

    Source

    MeSH

    Animal Husbandry
    Animals
    Carbon
    Carbon Dioxide
    Cattle
    Ecosystem
    Environmental Monitoring
    Global Warming
    Methanol
    Nitrogen
    Nitrous Oxide
    Poaceae
    Rain
    Soil
    Sunlight
    Temperature
    Time Factors

    Pub Type(s)

    Journal Article
    Research Support, U.S. Gov't, Non-P.H.S.

    Language

    eng

    PubMed ID

    20400576

    Citation

    TY - JOUR T1 - Grazing management contributions to net global warming potential: a long-term evaluation in the Northern Great Plains. AU - Liebig,M A, AU - Gross,J R, AU - Kronberg,S L, AU - Phillips,R L, AU - Hanson,J D, Y1 - 2010/04/13/ PY - 2010/4/20/entrez PY - 2010/4/20/pubmed PY - 2010/5/26/medline SP - 799 EP - 809 JF - Journal of environmental quality JO - J. Environ. Qual. VL - 39 IS - 3 N2 - 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 (N(2)O) and methane (CH(4)). 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) CO(2) emissions associated with N fertilizer production and application, (ii) literature-derived estimates of CH(4) production for enteric fermentation, (iii) change in soil organic carbon (SOC) over 44 yr using archived soil samples, and (iv) soil-atmosphere N(2)O and CH(4) 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 CH(4) (<2.0 kg CH(4)-C ha(-1) yr(-1)). Greater N inputs within CWP contributed to annual N(2)O emission nearly threefold greater than HGP and MGP. Due to differences in stocking rate, CH(4) 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 CO(2equiv.) sinks, while CWP was a net CO(2equiv.) 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. SN - 0047-2425 UR - https://www.unboundmedicine.com/medline/citation/20400576/Grazing_management_contributions_to_net_global_warming_potential:_a_long_term_evaluation_in_the_Northern_Great_Plains_ L2 - http://dl.sciencesocieties.org/publications/jeq/articles/39/3/799 ER -