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Long-term impacts of manure amendments on carbon and greenhouse gas dynamics of rangelands.

Abstract

Livestock manure is applied to rangelands as an organic fertilizer to stimulate forage production, but the long-term impacts of this practice on soil carbon (C) and greenhouse gas (GHG) dynamics are poorly known. We collected soil samples from manured and nonmanured fields on commercial dairies and found that manure amendments increased soil C stocks by 19.0 ± 7.3 Mg C ha(-1) and N stocks by 1.94 ± 0.63 Mg N ha(-1) compared to nonmanured fields (0-20 cm depth). Long-term historical (1700-present) and future (present-2100) impacts of management on soil C and N dynamics, net primary productivity (NPP), and GHG emissions were modeled with DayCent. Modeled total soil C and N stocks increased with the onset of dairying. Nitrous oxide (N2 O) emissions also increased by ~2 kg N2 O-N ha(-1)  yr(-1) . These emissions were proportional to total N additions and offset 75-100% of soil C sequestration. All fields were small net methane (CH4 ) sinks, averaging -4.7 ± 1.2 kg CH4 -C ha(-1)  yr(-1) . Overall, manured fields were net GHG sinks between 1954 and 2011 (-0.74 ± 0.73 Mg CO2 e ha(-1)  yr(-1) , CO2 e are carbon dioxide equivalents), whereas nonmanured fields varied around zero. Future soil C pools stabilized 40-60 years faster in manured fields than nonmanured fields, at which point manured fields were significantly larger sources than nonmanured fields (1.45 ± 0.52 Mg CO2 e ha(-1)  yr(-1) and 0.51 ± 0.60 Mg CO2 e ha(-1)  yr(-1) , respectively). Modeling also revealed a large background loss of soil C from the passive soil pool associated with the shift from perennial to annual grasses, equivalent to 29.4 ± 1.47 Tg CO2 e in California between 1820 and 2011. Manure applications increased NPP and soil C storage, but plant community changes and GHG emissions decreased, and eventually eliminated, the net climate benefit of this practice.

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  • Authors+Show Affiliations

    ,

    Department of Environmental Science, Policy & Management, University of California, 137 Mulford Hall #3114, Berkeley, CA, 94720, USA.

    ,

    Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80523, USA.

    Department of Environmental Science, Policy & Management, University of California, 137 Mulford Hall #3114, Berkeley, CA, 94720, USA.

    Source

    Global change biology 21:12 2015 Dec pg 4533-47

    MeSH

    Air Pollutants
    California
    Carbon
    Carbon Dioxide
    Dairying
    Gases
    Global Warming
    Greenhouse Effect
    Manure
    Methane
    Models, Theoretical
    Nitrous Oxide
    Seasons
    Soil
    Time

    Pub Type(s)

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

    Language

    eng

    PubMed ID

    26183573

    Citation

    TY - JOUR T1 - Long-term impacts of manure amendments on carbon and greenhouse gas dynamics of rangelands. AU - Owen,Justine J, AU - Parton,William J, AU - Silver,Whendee L, Y1 - 2015/09/22/ PY - 2015/3/5/received PY - 2015/7/2/accepted PY - 2015/9/22/aheadofprint PY - 2015/7/18/entrez PY - 2015/7/18/pubmed PY - 2016/8/17/medline KW - DayCent KW - carbon sequestration KW - greenhouse gas emissions KW - manure KW - pasture KW - rangelands KW - soil SP - 4533 EP - 47 JF - Global change biology JO - Glob Chang Biol VL - 21 IS - 12 N2 - Livestock manure is applied to rangelands as an organic fertilizer to stimulate forage production, but the long-term impacts of this practice on soil carbon (C) and greenhouse gas (GHG) dynamics are poorly known. We collected soil samples from manured and nonmanured fields on commercial dairies and found that manure amendments increased soil C stocks by 19.0 ± 7.3 Mg C ha(-1) and N stocks by 1.94 ± 0.63 Mg N ha(-1) compared to nonmanured fields (0-20 cm depth). Long-term historical (1700-present) and future (present-2100) impacts of management on soil C and N dynamics, net primary productivity (NPP), and GHG emissions were modeled with DayCent. Modeled total soil C and N stocks increased with the onset of dairying. Nitrous oxide (N2 O) emissions also increased by ~2 kg N2 O-N ha(-1)  yr(-1) . These emissions were proportional to total N additions and offset 75-100% of soil C sequestration. All fields were small net methane (CH4 ) sinks, averaging -4.7 ± 1.2 kg CH4 -C ha(-1)  yr(-1) . Overall, manured fields were net GHG sinks between 1954 and 2011 (-0.74 ± 0.73 Mg CO2 e ha(-1)  yr(-1) , CO2 e are carbon dioxide equivalents), whereas nonmanured fields varied around zero. Future soil C pools stabilized 40-60 years faster in manured fields than nonmanured fields, at which point manured fields were significantly larger sources than nonmanured fields (1.45 ± 0.52 Mg CO2 e ha(-1)  yr(-1) and 0.51 ± 0.60 Mg CO2 e ha(-1)  yr(-1) , respectively). Modeling also revealed a large background loss of soil C from the passive soil pool associated with the shift from perennial to annual grasses, equivalent to 29.4 ± 1.47 Tg CO2 e in California between 1820 and 2011. Manure applications increased NPP and soil C storage, but plant community changes and GHG emissions decreased, and eventually eliminated, the net climate benefit of this practice. SN - 1365-2486 UR - https://www.unboundmedicine.com/medline/citation/26183573/Long_term_impacts_of_manure_amendments_on_carbon_and greenhouse_gas_dynamics_of_rangelands_ L2 - http://dx.doi.org/10.1111/gcb.13044 ER -