|Todd, Richard - Rick|
|RHOADES, MARTY - West Texas A & M University|
Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 2/27/2011
Publication Date: 8/1/2011
Citation: Cole, N.A., Todd, R.W., Parker, D.B., Rhoades, M., Mason, A.M. 2011. Ammonia emissions from a commercial feedyard measured using passive samplers and a box model [abstract]. Journal of Animal Science. 89, E-Suppl.1:757.
Technical Abstract: Animal feeding operations are a major source of ammonia gas emitted to the atmosphere. Ammonia emissions can potentially affect air quality and sensitive ecosystems. Measuring ammonia emissions from open lots is difficult; therefore, few studies have investigated ammonia losses from beef cattle feedyards. Our objective was to measure ammonia emissions from a 77-ha, 45,000-head beef cattle feedyard on the Southern High Plains. Profiles of ammonia concentration, wind speed, and air temperature were measured downwind (5 d in summer) or in the middle (6 d in winter) of the feedyard. In addition, ammonia concentrations were measured at seven locations downwind (summer) or in the middle (winter) of the yard using a combination of active and passive samplers. Ammonia flux was estimated using a box model. Samples of rations, fresh feces, pen manure, and compost were obtained for chemical analyses (DM, N, P). Dietary N concentrations averaged 2.14% during the summer and 2.51% during the winter. Hourly ammonia-N flux averaged 365+/-49 mg/m**2 in the summer and 212+/-92 mg/m**2 in the winter. Ammonia N emission rates averaged 5,453+/-741 kg/d in the summer (63% of N intake), and 3,170+/-1,383 kg/d in the winter (31% of N intake), with an annualized average of 4,311+/-1,612 kg/d (47% of N intake). Nitrogen volatilization losses, estimated from the changes in the N:P ratio of rations and dry pen manure, averaged 42% of N intake. The annualized emission factor was 15.4+/-2.2 kg ammonia-N/head fed. Nitrogen volatilization losses from the compost windrows, estimated from changes in the N:P ratio of manure and compost, averaged 3.4+/-1.4% of N placed in the windrows during winter and 13.3+/-1.3% in summer. Ammonia-N volatilization losses from the retention pond, estimated using an empirical model averaged 5.5+/-4.4 kg/ha daily or 166+/-130 kg/d. These values agree well with emissions estimated using an inverse dispersion model and demonstrate that the pen surfaces is the primary source of feedlot ammonia, and that emissions are greater in summer than winter. This research was partially supported by grant #TS2006-06009 from the USDA-CSREES.