There is a need for a robust and accurate technique to measure ammonia (NH_3) emissions from animal feeding operations (AFOs) to obtain emission inventories and to develop abatement strategies. Two consecutive seasonal studies were conducted to measure NH_3 emissions from an open-lot dairy in central Texas in July and December of 2005. Data including NH_3 concentrations were collected and NH_3 emission fluxes (EFIs), emission rates (ERs), and emission factors (EFs) were calculated for the open-lot dairy. A protocol using flux chambers (FCs) was used to determine these NH_3 emissions from the open-lot dairy. NH_3 concentration measurements were made using chemiluminescence-based analyzers. The ground-level area sources (GLAS) including open lots (cows on earthen corrals), separated solids, primary and secondary lagoons, and milking parlors were sampled to estimate NH_3 emissions. The seasonal NH_3 EFs were 11.6 ± 7.1 kg-NH_3 yr~(-1)head~(-1) for the summer and 6.2 ± 3.7 kg-NH_3 yr~(-1)head~(-1) for the winter season. The estimated annual NH_3 EF was 9.4 ±5.7 kg-NH_3 yr~(-1)head~(-1) for this open-lot dairy. The estimated NH_3 EF for winter was nearly 47% lower than summer EF. Primary and secondary lagoons (～37) and open-lot corrals (～63%) in summer, and open-lot corrals (～95%) in winter were the highest contributors to NH_3 emissions for the open-lot dairy. These EF estimates using the FC protocol and real-time analyzer were lower than many previously reported EFs estimated based on nitrogen mass balance and nitrogen content in manure. The difference between the overall emissions from each season was due to ambient temperature variations and loading rates of manure on GLAS. There was spatialrnvariation of NH_3 emission from the open-lot earthen corrals due to variable animal density within feeding and shaded and dry divisions of the open lot. This spatial variability was attributed to dispirit manure loading within these areas.
展开▼
