Location: Dairy Forage ResearchTitle: Ammonia Emissions from Dairy Production Systems in Wisconsin Author
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2008
Publication Date: 4/20/2009
Citation: Harper, L.A., Flesch, T.K., Powell, J.M., Coblentz, W.K., Jokela, W.E., Martin, N.P. 2009. Ammonia Emissions from Dairy Production Systems in Wisconsin. Journal of Dairy Science. 92:2326-2337. Interpretive Summary: Ammonia in the atmosphere is an environmental concern because it is the main basic gas that neutralizes atmospheric acid gases that are produced from the combustion of fossil fuels; this reaction produces an aerosol that is a component of atmospheric haze and is implicated as a potential human health hazard. Ammonia is emitted from dairy farms, but there has been little data showing the total amount and whether or not the amount varies from season to season or with different management options used on farms. We conducted studies to obtain representative and accurate ammonia emissions data from large dairy farms in Wisconsin. Ammonia concentrations and climatic measurements were made on three dairy farms (>800 cows) during the winter, summer, and autumn. Our results showed that ammonia emissions from Wisconsin dairy farms were considerably smaller than currently-used estimates of dairy ammonia emissions; and they were significantly smaller than measured emissions from other types of animal-feeding operations. This information can help dairy producers reduce ammonia emissions from their farms; and it provides other scientists and policy makers with more accurate, scientifically based information about dairy farming’s impact to the environment.
Technical Abstract: Ammonia (NH3) gas is reactive and is the major basic gas that neutralizes atmospheric acid gases produced from combustion of fossil fuels. This reaction produces an aerosol that is a component of atmospheric haze and is implicated in nitrogen (N) deposition and as a potential human health hazard. The objective of these studies was to obtain representative and accurate NH3 emissions data from large dairy farms (> 800 cows) in Wisconsin. Ammonia concentrations and climatic measurements were made on three dairy farms during winter, summer, and autumn to calculate emissions using an inverse-dispersion analysis technique. These study farms used freestall barn systems with nearby sand separators and lagoons for waste management. Emissions were calculated from the whole-farm, from the barns, and from the waste-management system components (lagoons and sand separators). During winter, the lagoons’ NH3 emissions were so small as to not be measurable. During autumn and summer, whole-farm emissions were significantly larger than winter with about two-thirds of the total emissions from the waste management systems. The mean whole-farm winter, autumn, and summer NH3 relative emissions were 1.5, 7.5, and 13.7% of feed N inputs, respectively. Average annual emissions comparisons between the three farms were similar at 7.0, 7.5, and 8.4% of input feed N emitted as NH3, with an annual average for all three farms of 7.6 ± 1.5%. These winter, summer, autumn, and average annual NH3 emissions are considerably smaller than currently-used estimates for dairy farms and smaller than emissions from other types of animal-feeding operations.