COMET-Global : Greenhouse gas accounting system

Land use affects the release of soil gases like carbon dioxide, nitrous oxide and methane to the atmosphere, which contribute to global warming. A farm-level greenhouse gas (GHG) accounting system will allow farmers and decision makers worldwide to quantify the impact of planned land use and management changes on GHG emissions from agricultural soils.

  • Background (completed research project)

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    Previous research has thoroughly investigated effects of land use and management changes on GHG emissions, but these findings have hardly been implemented in practice as a GHG reduction strategy.

  • Aim

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    The primary aim was to evaluate long-term effects of a range of management practices and their combinations on crop yields and GHG emissions from agricultural soils at the site and regional scales in Switzerland.

    Secondary aim was to develop COMET-Global, a decision support tool that will allow GHG emissions assessments from individual farms based on COMET-Farm operational in the US.

  • Results

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    Soils under conventional practices were a net source of soil GHG emissions. Application of partially decomposed organic fertilizers in combination with reduced tillage and winter vetch cover cropping showed the highest mitigation potential, however it reduced mean crop yields by up to 36%. In contrast, an application of organic manure with high decomposability in combination with reduced tillage and cover cropping substantially reduced GHG emissions and increased crop yields. Increases in soil organic carbon accounted for 86–100% of GHG mitigation potentials.

  • Implication for research

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    We quantified GHG mitigation potentials associated with the long-term adoption of a range of management practices at site and regional scales. The results improved our understanding of the effects of management practices on soil GHG emissions at longer temporal and larger spatial scales. Insights from our analyses can guide designing future GHG field experiments. DayCent model parameterization can be applicable to other modeling studies.

  • Implication for practice

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    Estimates of GHG mitigation potentials and yields for a range of management practices might promote adoption of practices that effectively mitigate GHG emissions without a commensurate decrease in crop yields, and thus are relevant to farmers, land managers, and extension officers. The regional scale estimates provide policy and decision makers with information to set up a feasible target for climate change mitigation strategies in Switzerland. The COMET-Global provides an improved methodology for a full GHG emissions assessment from agricultural resources, universally accessible to farmers and decision makers.

  • Original title

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    COMET-Global: Whole-farm GHG estimation and environmental diagnostic platform