Beef cattle are the largest source of greenhouse gas (GHG) emissions in the livestock sector and the broader agri-food system. Adaptive multipaddock (AMP) grazing, an intensive form of rotational grazing aimed at improving forage and animal productivity, has been proposed as a rare, low-input, low-cost strategy to potentially offset beef emissions by boosting soil carbon (C) sequestration. However, the long-term (>10 years) impact of AMP on soil C sequestration in grazinglands and net GHG emissions in the entire cow-calf to finish beef production system, using longitudinal soil C monitoring, remains highly uncertain. To study these impacts, we conducted a life cycle assessment (LCA) using eleven years of on-farm input data and soil C measurements from the Lake City AgBioResearch Center in the Upper Midwest. We compared two beef production systems: AMP-only and AMP+FL (where FL stands for feedlot). Both systems employed AMP grazing during the cow-calf and stocker phases, differing only in the finishing strategy: grass-finishing under AMP for AMP-only and FL-finishing for AMP+FL. Our impact scope included emissions from enteric methane, manure management, feed production, on-farm energy use and transportation, and potential soil C sequestration. Soil C sequestration in AMP-managed pastures averaged 1.70 Mg C ha-1 yr-1 over eleven years. Including soil C into the GHG balance, AMP-only emissions were reduced from 29.80 to -10.04 kg CO2-e/kg CW (133%), and AMP+FL emissions from 25.85 to -2.41 kg CO2-e/kg CW (109%). These data indicate that both systems could become net C sinks over the eleven years. However, the observed drop in soil C sequestration from years 4 to 11 in the top 30 cm suggests that the sequestration rate is slowing, thus impacting offsetting potential. Despite this, AMP grazing may already offer a solution for significant long-term (>10 years) climate benefits while maintaining beef production and farm resilience in current beef grazing systems in the Upper Midwest.
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