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United States Department of Agriculture

Agricultural Research Service

Title: Rate and Frequency of Urease Inhibitor Application for Minimizing Ammonia Emissions from Beef Cattle Feedyards

Authors
item Parker, D. - WTAMU
item Pandrangi, S. - WTAMU
item Greene, L. - TAES
item Almas, L. - WTAMU
item Cole, Noel
item Rhoades, M. - WTAMU
item Koziel, J. - TAES

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 18, 2005
Publication Date: February 5, 2005
Citation: Parker, D.B., Pandrangi, S., Greene, L.W., Almas, L.K., Cole, N.A., Rhoades, M.B., Koziel, J.A. 2005. Rate and frequency of urease inhibitor application for minimizing ammonia emissions from beef cattle feedyards. Transactions of the ASAE. 48(2):787-793.

Interpretive Summary: Ammonia is often emitted from livestock manures. The effects of animal feeding operations on the environment is a concern of producers, regulators, and the general public. Decreasing emissions of ammonia from beef cattle feedlots may have beneficial effects on air quality downwind of the feedlot as well as retain nitrogen in the manure and make if more valuable as a fertilizer. Most ammonia is apparently generated by the action of enzymes, called ureases on urea present in animal urine. Therefore, a laboratory study was conducted to evaluate how the rate and timing of urease inhibitor application affect ammonia emissions from simulated beef cattle feedyard manure surfaces. The urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT) was applied at rates of 0, 1 and 2 kg/ha, at 8, 16, and 32 day frequencies, and with or without simulated rainfall. Synthetic urine was added every 2 days to the manure surface. Gaseous ammonia was trapped using a vacuum system. Applying NBPT applied every 8 days was most effective in reducing ammonia losses: reductions in ammonia emissions were 49% and 66% with the 1 and 2 kg/ha NBPT treatments, respectively. The 8-day, 1 kg/ha NBPT treatment had the most promising cost/benefit ratio of 0.48. Simulated rainfall reduced the ammonia emission rates slightly. The use of NBPT for reducing ammonia emissions looks promising, however, the buildup of urea in the pen surface may require that the NBPT additions increase with time.

Technical Abstract: Reduction of ammonia emissions from animal feeding operations is important from the perspective of environmental policy and its impact on agriculture. A laboratory study was conducted to evaluate how rate and timing of urease inhibitor application affect ammonia emissions from simulated beef cattle feedyard manure surfaces. The urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT) was applied at rates of 0, 1 and 2 kg/ha, at 8, 16, and 32 day frequencies, and with or without simulated rainfall. Synthetic urine was added every 2 days to the manure surface. Gaseous ammonia was trapped in a sulfuric acid solution using a vacuum system and analyzed for nitrogen using automated procedures. NBPT applied every 8 days was most effective, with the 1 and 2 kg/ha NBPT treatments resulting in 49 and 66% reduction in ammonia emission rates, respectively. The 8-day, 1 kg/ha NBPT treatment had the most promising cost/benefit ratio of 0.48. Simulated rainfall reduced the ammonia emission rates slightly as compared to the non-rainfall treatments, though the differences were not statistically different. The use of NBPT for reducing ammonia emissions looks promising, however, the buildup of urea may require an increased amount of added NBPT with time.

Last Modified: 7/25/2014
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