Title: Methane and ammonia emmissions from beef feeding in a U.S. southern High Plains region Authors
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 23, 2013
Publication Date: June 24, 2013
Citation: Flesch, T.K., Todd, R.W., Cole, N.A., Wilson, J.D. 2013. Methane and ammonia emmissions from beef feeding in a U.S. southern High Plains region. 5th Greenhouse Gases and Animal Agriculture Conference, June 23-26, 2013, Dublin, Ireland. Advances in Animal Biosciences, Cambridge University Press, 4(2):469. Interpretive Summary: Large amounts of the gases methane and ammonia can escape from cattle feedyards into the atmosphere. We used a method that did not interfere with the usual conditions at a commercial beef feedyard to measure how much methane and ammonia was lost from the feedyard. Data were collected during summer, winter and spring, from 2004 to 2005. Ammonia loss was greatest during midday, when temperature and air movement was greatest. On the other hand, methane loss was not related to these variables, but rather to the time of day when cattle were fed. Greatest ammonia loss was during summer and spring; winter losses were 51% of those in summer. From 0.76 to 0.15 kilograms of ammonia per animal per day were lost. Half of the nitrogen contained in cattle feed was lost in the form of ammonia. Methane was lost at the rate of 0.86 to 0.183 kilograms per animal per day. On average, 1.6% of the cattle feed dry matter was lost as methane. Ammonia loss responded strongly to temperature, while methane loss responded more to animal behavior and stress.
Technical Abstract: Concentrated animal feeding operations (CAFO) are significant sources of methane and ammonia that escape into the atmosphere. Non-interfering micrometeorological methods are especially useful to quantify emissions from CAFO. The objective of this study was to simultaneously evaluate the emissions of methane (CH4) and ammonia (NH3) from a cattle-feeding CAFO. The study was conducted at a commercial feedyard on the semi-arid High Plains of Texas during winter and summer, 2004, and spring, 2005. Emissions were quantified using open path laser spectroscopy and inverse dispersion analysis. Other collected data included animal population, total feed and diet composition. Ammonia emissions peaked during midday, responding to greater source concentration, temperature and atmospheric turbulence. Methane emissions were not correlated with time of day, but rather with cattle time-of-feeding. Per capita NH3 emissions were 0.076, 0.150 and 0.149 kg NH3/animal/day in winter, spring and summer, respectively. On average, 52% of fed nitrogen was lost as NH3. Per capita CH4 emissions were 0.183, 0.086 and 0.112 kg CH4/animal/day in winter, spring and summer, respectively. Methane emissions averaged 1.6% of input feed dry matter. Ammonia emissions were seasonal with greater emissions during warmer periods. Methane emissions were less during reduced stress periods compared with greater heat/cold weather conditions.