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143 Impacts of soil carbon sequestration on life cycle greenhouse gas emissions in midwestern USA beef finishing systems

Authors
  • Rowntree, Jason1
  • Stanley, Paige2
  • Beede, David1
  • DeLonge, Marcia3
  • Hamm, Michael1
  • 1 Michigan State University
  • 2 University of California, Berkeley
  • 3 Union of Concerned Scientists
Type
Published Article
Journal
Journal of Animal Science
Publisher
Oxford University Press
Publication Date
Dec 05, 2019
Volume
97
Issue
Suppl 3
Pages
147–148
Identifiers
DOI: 10.1093/jas/skz258.302
PMCID: PMC6898136
Source
PubMed Central
Keywords
Disciplines
  • ORAL PRESENTATIONS
  • Production, Management and Environment
License
Unknown

Abstract

Using life cycle analysis (LCA), several studies have concluded that grass-finished beef systems have greater GHG intensities than feedlot-finished (FL) beef systems. These studies evaluated only one grazing management system– continuous grazing – and assumed steady-state soil carbon (C), to model the grass-finishing environmental impact. However, by managing for more optimal forage growth and recovery, adaptive multi-paddock (AMP) grazing can improve animal and forage productivity, potentially sequestering more soil organic carbon (SOC) than continuous grazing. To examine impacts of AMP grazing and related SOC sequestration on net GHG emissions, a comparative LCA was performed of two different beef finishing systems in the Upper Midwest, USA: AMP grazing and FL. We used on-farm data collected from the Michigan State University Lake City AgBioResearch Center for AMP grazing. Impact scope included GHG emissions from enteric methane, feed production and mineral supplement manufacture, manure, and on-farm energy use and transportation, as well as the potential C sink arising from SOC sequestration. Across-farm SOC data showed a 4-year C sequestration rate of 3.59 Mg C ha−1 yr−1 in AMP grazed pastures. After including SOC in the GHG footprint estimates, finishing emissions from the AMP system were reduced from 9.62 to −6.65 kg CO2-e kg carcass weight (CW)−1, whereas FL emissions increased slightly from 6.09 to 6.12 kg CO2-e kg CW−1 due to soil erosion. This indicates that AMP grazing has the potential to offset GHG emissions through soil C sequestration, and therefore the finishing phase could be a net C sink. However, FL production required only half as much land as AMP grazing. This research suggests that AMP grazing can contribute to climate change mitigation through SOC sequestration and challenges existing conclusions that only feedlot-intensification reduces the overall beef GHG footprint through greater productivity.

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