Environmental concern and awareness has encouraged all industries, including the livestock sector of food production, to assess their contributions to the greenhouse gases (GHG) emitted into the atmosphere. The main greenhouse gases associated with livestock and poultry include carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Methane has 24 times and nitrous oxide has 298 times the global warming potential, or “greenhouse effect,” of CO2. When discussing GHG emissions, CH4 and N2O are expressed as carbon dioxide equivalents (CO2e). Carbon footprint is often times used as a general reference to the amount of GHG emitted from the sum of activities.
While CO2 is the standard by which greenhouse gases are measured, CH4 from enteric digestion and manure storage and N2O related to the production of crops used for feed and also from manure storage make significant contributions to the total carbon footprint of livestock production.
Two livestock commodity groups have taken an active role in assessing their commodity’s carbon footprint. The Center for Agriculture and Rural Sustainability at the University of Arkansas has modeled the carbon footprint for the dairy industry, providing milk producers a baseline for their industry’s carbon footprint. This assessment was supported by Dairy Management, Inc. The National Pork Board supported the development of the Live Swine Carbon Footprint Calculator, a tool for estimating GHG emissions from individual farms which was written by Dr. Rick Ulrich and Dr. Greg Thoma, both faculty at the University of Arkansas. A previous MSU Extension News for Agriculture article discussed the use and availability of the swine footprint calculator. That article may be found at: http://news.msue.msu.edu/news/article/live_swine_carbon_footprint_calculator_is_now_available_for_pork_producers .
Dr. Marty Matlock from University of Arkansas’s Center for Agriculture and Rural Sustainability presented the Center’s findings on the dairy farm’s carbon footprint while speaking at the 2011 Michigan Agriculture’s Conference on the Environment. Enteric methane makes a large contribution to the carbon footprint on dairy farms due to rumen digestion. According to Dr. Matlock’s presentation, on average, 33% of the CO2e emissions from a dairy farm is the result of enteric digestion; manure management contributes another 33% of the farm CO2e emissions, feed is approximately 26% and on-farm energy use, 4%.