Submitted to: Proceeding of Plains Nutrition Council Symposium
Publication Type: Proceedings
Publication Acceptance Date: 3/30/2004
Publication Date: 4/15/2004
Citation: Harper, L.A., Cole, N.A., Flesch, T.K., Sharpe, R.R., Todd, R.W., Wilson, J.D. 2004. Ammonia from livestock operations: Measurement technologies and emissions. Proceeding of Plains Nutrition Council Symposium. p. 27-50. Interpretive Summary: Ammonia is an air-quality gas emitted from animal feeding operations. It is a difficult gas to measure accurately because it sticks to measurement equipment. Because of its characteristics, its concentration and transport measurement require techniques that do not interfere with its chemical properties and the wind which moves it away from the source. The purpose of this report by scientists at the J.P. Campbell, Sr. Natural Resource Conservation Center, USDA-ARS, at Watkinsville, GA; the Conservation and Production Research Laboratory, USDA-ARS, Bushland, TX; and University of Alberta, Edmonton, is to review available transport technologies and discuss their strengths and weaknesses. Emissions were presented showing differences due to measurement techniques and time-of-year studies. Comparisons were made between ammonia and another gas emissions from a beef feedlot showing 1) the relationship between emissions of the two gases, 2) the relationship between source emissions and concentrations in the atmosphere, and 3) the importance of having good technology to evaluate emissions. The use of appropriate technologies will provide accurate air-quality gas emissions estimates for environmental protection agencies the animal industries, and designers to identify problem areas and to develop best-management practices for reducing emissions. Reduction of air-quality gas emissions by animal feeding operations will minimize environmental impact while continuing to provide a safe food supply.
Technical Abstract: Ammonia (NH3) is a difficult gas to measure and its chemical properties dictate the use of transport technologies that do not interfere with the source temperature, concentration, pH, and turbulent or diffusive transport. The purpose of this report is to review available atmospheric-exchange and transport technologies and discuss their strengths and weaknesses. Chamber techniques affect the microclimate of the site and should not be used for diffusive types of gases such as NH3. Flux-gradient and dispersion-analysis techniques are preferred for both air-quality and greenhouse gases; however, these techniques require large, relatively-homogenous sources for wind and concentration for vertical-profile development. Integrated horizontal flux techniques work well for small-area, homogenous source studies and mass-balance techniques work well for small-area, non-homogenous studies. Comparison of measurement techniques resulted in a five-fold difference in determined NH3 emissions between microclimate and tracer techniques. Emissions factors were presented showing differences due to measurement techniques, time-of-year, and unit-basis of comparisons. Comparison was made between NH3 and enteric CH4 emissions from a beef feedlot showing the relationship between types of emissions (biological vs. diffusive), the lack of relationship between atmospheric concentration of gases and emissions, and the importance of having good technology to evaluate emissions.