|Todd, Richard - Rick|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2010
Publication Date: 12/1/2010
Citation: Rhoades, M.B., Parker, D.B., Cole, N.A., Todd, R.W., Caraway, E.A., Auvermann, B.W., Topliff, D.R., Schuster, G.L. 2010. Continuous ammonia emission measurements from a commercial beef feedyard in Texas. Transactions of the ASABE. 53(6):1823-1831. Interpretive Summary: Ammonia is a nitrogen-containing gas that is emitted from the urine of animals. At beef feedyards, urine is deposited directly on the open feedlot pen surface, and a considerable portion of the ammonia is volatilized into the atmosphere. The quantify of ammonia volatilized is dependent on many factors including weather and type of feed. Ammonia can combine with other compounds to form fine dust particles that can affect health and degrade air quality. In the past, beef feedyard owners have been required to report the amount of ammonia that is emitted from their feedyards. Thus, it is important that emission estimates are accurate and representative of the atmospheric conditions within the region. Ammonia emissions were monitored continuously for a year at a commercial beef feedyard in the Southern High Plains. On a daily basis, ammonia concentrations were highest during the afternoon and lowest at night. On an annual basis, the ammonia concentration measured near the center of the feedyard averaged 0.57 parts per million, and 50 percent of the nitrogen fed to the animals was eventually excreted and volatilized as ammonia gas. On a per animal basis, 83 grams of ammonia nitrogen was volatilized for every beef animal produced at the feedyard.
Technical Abstract: Ambient NH3 concentrations were measured continuously at a beef cattle feedyard for 12 months beginning in March 2007. Concentrations were measured every five minutes, 24 hours per day, at a sample intake height of 3.3 m using a chemiluminescence analyzer. On-site weather data was collected concurrently. Modeled emissions of NH3 were compared to the mass balance of N for the feedyard. Mean annual NH3 concentrations were 0.57 ppm, with a monthly average low of 0.37 ppm in December 2007 and a monthly average high of 0.77 ppm in August 2007. Flux densities were calculated using a backward Lagrangian stochastic model (WindTrax 22.214.171.124). Mean annual flux density was 70.7 µg m**-**2s**-**1. Mean monthly flux density ranged from 42.7 to 123.1 µg m**-**2s**-**1 in November and April 2007, respectively. Both concentration and flux density had a diel distribution with minima during the nighttime hours and maxima during the early afternoon. On an annual basis, 50.0% of fed N was volatilized as NH3. A per-head production-based pen emission coefficient was calculated as 83.0 g NH3-N (head fed)**-**1 day**-**1.