Transactions of the ASABE Vol. 51(5): 1783-1790 E 2008 American Society of Agricultural and Biological Engineers ISSN 0001-2351 1783 TECHNICAL NOTE: COMPARISON OF THREE TECHNIQUES FOR DETERMINING AMMONIA EMISSION FLUXES FROM BROILER LITTER Z. Liu, L. Wang, D. B. Beasley ABSTRACT. This article reports an experimental study of three techniques in ammonia emission flux determination. Ammonia concentrations in a dynamic flow‐through chamber with broiler litter were measured simultaneously by a chemiluminescence ammonia analyzer and an acid scrubber. At the beginning and ending of each test, the litter samples were analyzed for conducting nitrogen mass balance. Ammonia emissions were estimated from the two concentration measurements and the mass balance approach. It was observed that the chemiluminescence analyzer measurements tended to overestimate ammonia concentration compared with the acid scrubber measurements, especially when litter moisture was high. Statistical results indicated that the effect of litter moisture content on the ratios of the average chemiluminescence analyzer measurements over the acid scrubber measurements was significant, and a p‐value of 0.0104 was obtained. Great uncertainties were observed for the mass balance approach, especially when the percentages of the total nitrogen losses in litter samples were small (less than 2%). In order to apply the mass balance approach to estimate ammonia emissions and to achieve acceptable accuracy, a substantially long testing period (more than 80 h) is needed under the observed ammonia emission level (104 to 1137 mg N h -1 m -2 ), and great efforts are needed to reduce the uncertainties associated with sampling and analyzing litter nitrogen content. Keywords. Acid scrubber, Air emission, Ammonia concentration, Ammonia fluxes, Chemiluminescence NH 3 analyzer, Nitrogen mass balance. nimal feeding operations (AFOs) have expanded greatly over the past few decades in the U.S. In the meantime, intensive production of poultry and livestock has raised serious environmental con‐ cerns with the public, and it is often perceived to be a signifi‐ cant source of pollutants that may pose threats to the health and welfare of surrounding communities. Among air emis‐ sions from AFOs, ammonia has become an increasing con‐ cern to both regulatory agencies and animal producers. High concentrations of ammonia inside the animal houses are det‐ rimental to the health and performance of animals (Brewer and Costello, 1999), and emissions of ammonia may cause damage to the ecosystems (van Breemen et al., 1982). The importance of ammonia emissions from AFOs has been well recognized (Wheeler et al., 2003; Gates et al., 2004). In the literature, wide variations have been found for am‐ monia emissions from AFOs among different studies. The re‐ ported ammonia emission fluxes from broiler houses under different conditions may differ by up to 55 times (Redwine et al., 2002). While such variations in ammonia emissions Submitted for review in July 2007 as manuscript number SE 7081; approved for publication by the Structures & Environment Division of ASABE in September 2008. Presented at the 2006 ASABE Annual Meeting as Paper No. 064189. The authors are Zifei Liu, ASABE Member Engineer, Graduate Student, Lingjuan Wang, ASABE Member Engineer, Assistant Professor, and David B. Beasley, ASABE Fellow, Professor, Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, North Carolina. Corresponding author: Lingjuan Wang, Campus Box 7625, North Carolina State University, Raleigh, NC 27695‐7625; phone: 919‐515‐6762; fax: 919‐515‐7760; e‐mail: Lwang5@ ncsu.edu. could mainly be attributed to the differences in management practices and seasonal or regional conditions, the uncertain‐ ties associated with the different methods used in measuring and computing ammonia emissions may also be one of the reasons. Accurate estimation of ammonia emission rates from individual operations is important and yet a challenging task. Hence, there is a need for studying different measure‐ ment techniques used in ammonia emission determination. Currently, there are no standard methods and protocols for measuring and estimating ammonia emissions from AFO fa‐ cilities. Some commonly used techniques for determining ammonia emissions include: (1) standard wet laboratory analysis with an acid scrubber system, which usually pro‐ vides measurement of average concentrations over a relative‐ ly long period of time (the common averaging time can be from several hours to several days); (2) instrumentation anal‐ ysis such as the chemiluminescence ammonia analyzer, which is able to measure ammonia concentrations continu‐ ously along with time; and (3) the nitrogen mass balance ap‐ proach, which is the basis for conducting “processing‐based” model analyses to determine gas emissions from AFO houses recommended by the National Academy of Sciences (NRC, 2003). In the first two techniques, ammonia emission fluxes can be calculated from measured concentrations and corre‐ sponding house ventilation rates. In the nitrogen mass bal‐ ance approach, the average ammonia emission fluxes can be estimated from total nitrogen losses of an emission source throughout a concerned period. The objective of this research was to investigate the differences in ammonia emission de‐ termination among these three techniques under various source conditions, and thus to address the limitations of these methods. A