Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 4, 2004
Publication Date: October 31, 2004
Citation: Harper, L.A., Flesch, T.K., Todd, R.W., Cole, N.A. 2004. Air-quality and global-change gas emissions in a beef feeding operation [abstract]. American Society of Agronomy Meetings. Paper No. 3805. CDROM. Technical Abstract: A significant percentage of fed cattle are in large commercial operations in the semi-arid/arid western Great Plains, mostly in areas with sparse human populations. However, the high density of animals in these confined operations can lead to air quality concerns both locally and regionally. There is a lack of appropriate factors to estimate trace-gas emissions from these types of operations. These studies were conducted to obtain appropriate estimates of ammonia and methane emissions from beef feeding operations and determine meteorological factors that affect emissions. Gas concentrations of ammonia and methane were measured using open-path laser spectrometry and micrometeorological data were taken to calculate trace-gas emissions using the backward Lagrangian stochastic analysis procedure. Both ammonia and methane (primarily enteric) emissions varied on a daily basis with the variability for ammonia much larger than methane. Wintertime ammonia emissions from the feedlot were about 29% and summertime emissions about 53% of feed nitrogen input. Water runoff retention pond ammonia emissions were less than 1% in winter and about 3% of feed nitrogen in summer. Feedlot methane emissions in wintertime were higher than summer with emissions of 0.18 and 0.11 kg CH4 per animal per day, respectively. Total ammonia emissions were less than published estimates and methane emissions were similar to previously-published measurements.