Life cycle assessment of contrasting grazing systems within a yearling stocker stage of beef cattle production

Life cycle assessment (LCA) was used to compare the environmental impacts of three grazing systems for beef cattle backgrounding in North Florida. The systems were grass + clover (GL), grass + clover + rhizoma peanut (GLRP), and grass + nitrogen fertilizer (GN). Our hypothesis was that incorporating legumes into grazing systems decreases reliance on fossil fuels and inorganic fertilizers and reduces the environmental impact of beef production systems. The LCA assessed five environmental impact categories: global warming potential, freshwater eutrophication, marine eutrophication, fossil fuel scarcity, and acidification potential. A cradle-to-farm gate system boundary encompassed the processes within the backgrounding stage. The functional unit adopted was 1 kg of liveweight gain. Results indicated that the GN system had the greatest environmental impacts, driven primarily by elevated nitrous oxide (N 2 O) emissions from synthetic N fertilizer use and methane (CH 4 ) emissions from enteric fermentation, along with greater fossil fuel consumption associated with fertilizer production and application. In contrast, GLRP impacted the environment less across all categories. This was attributed to legume biological N fixation, which reduced the need for synthetic fertilizers and, consequently, decreased greenhouse gas emissions, eutrophication potential, and acidification. This study highlights the potential of legume integration into grazing systems, particularly GLRP, as an alternative to N-fertilized grass systems. By reducing reliance on synthetic fertilizers and mitigating environmental impacts, GLRP enhanced the sustainability of beef production in North Florida. These findings document the value of legumes for improving the environmental performance of livestock systems, particularly as global demand for sustainable food production intensifies. • Life cycle assessment compared legume-integrated and nitrogen-fertilized grazing systems for beef cattle. • Legume-based systems reduced environmental impacts across all categories, especially greenhouse gas emissions and nutrient runoff. • Conventional grass-nitrogen systems had higher emissions and fossil fuel use due to synthetic fertilizer dependence. • Results support legume integration as a strategy for sustainable beef production in the southeastern U.S.