|Rotz, Clarence - Al|
Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2009
Publication Date: 6/11/2009
Citation: Chianese, D.S., Rotz, C.A., Richard, T.L. 2009. WHOLE FARM GREENHOUSE GAS EMISSIONS: A REVIEW WITH APPLICATION TO A PENNSYLVANIA DAIRY FARM. Applied Engineering in Agriculture. 25(3):431-442. Interpretive Summary: The control of greenhouse gas (GHG) emissions has become an important international issue. Although farmland can serve as a sink or storage for carbon sequestered from atmospheric carbon dioxide, agriculture is also an important source of emissions. As a sector, agriculture is reported to be the greatest contributor of nitrous oxide and the third greatest contributor of methane in the U.S. Thus, strategies must be developed to reduce or eliminate net emissions of greenhouse gases. Before these strategies can be developed, we must first understand typical emission ranges from each source on the farm in order to focus research and governmental policies on the processes with the greatest emissions. Potential sources on dairy farms include the soil, growing crops, animals, and manure during storage and handling. An extensive review of published GHG emission data shows that typical dairy farms in the Northeast are normally a net sink for carbon dioxide, but a source for methane and nitrous oxide emissions. Considering the global warming potential of these three gases, there is a net annual GHG emission from a 100-cow dairy farm equivalent to 504 to 1120 Mg of carbon dioxide. Further research is needed to more accurately quantify these emissions and to develop management strategies for reducing these emissions while maintaining profitable farms. Preserving viable and environmentally friendly farming systems is important to our national food supply and economy.
Technical Abstract: Greenhouse gas (GHG) emissions to the atmosphere and their potential impact on global climate change have become important concerns world-wide. Livestock production systems, such as dairy farms, provide both sinks and sources for GHG emissions. Farmland can serve as a carbon sink by providing a long-term storage for CO2 sequestered from the atmosphere through crop growth. Sources of GHG emissions on dairy farms include the soil, growing crops, animals, and the manure in animal housing facilities, during storage, and following field application. An extensive literature review was conducted to quantify typical emissions from the major GHG sources on dairy farms. From these typical levels, emissions were estimated for a representative, 100-cow dairy farm in Pennsylvania. Emissions from animal facilities primarily consisted of animal respiration (523 Mg CO2e/year) and enteric fermentation (2.2 Mg CH4/year) giving a total annual emission of 858 Mg CO2e. Manure storage emissions included CO2, CH4, and N2O for a total annual emission of 272 Mg CO2e. Cropland provided a net flux of -626 to -10 Mg CO2e /year depending upon the amount of manure carbon sequestered in the soil. For this representative farm, the estimated overall annual GHG emission was 504 to 1120 Mg CO2e. This review and farm analysis helps direct modeling efforts by determining the important physical processes that drive emissions of carbon dioxide, methane, and nitrous oxide in dairy production and providing expected ranges for these emissions. The review also expands the knowledge base of researchers, farm planners, and policymakers as they work to develop and maintain sustainable farming systems.