Characterization of ammonia emissions from ground level area sources at central texas dairies

There is a need for a robust and accurate technique to measure ammonia (NH3) emissions from animal feeding operations (AFOs) to obtain emission inventories and to develop abatement strategies. Seasonal studies were conducted to measure NH3 emissions from open-lot and free-stall dairies in central Texas since summer of 2003. Ammonia emission flux (EFl) was measured using an isolation flux chambers (FC) protocol from ground level area sources (GLAS) and converted to emission factor (EF) to potentially develop source specific NH3 emission control strategies. The GLAS including open-lots, free-stall barns, separated solids, primary and secondary lagoons and milking parlor were sampled to estimate NH3 emissions. In the first study, assessment of summer and winter data from the open-lot dairy indicated that overall NH3 EFs were 11.6 ?7.1 kg NH3 year-1 head-1 for the summer and 6.2 ?3.7 kg NH3 year-1 head-1 for the winter season. The estimated annual NH3 EF was 9.4 ?5.7 kg NH3 year-1 head-1 for this open-lot dairy. The estimated NH3 emission factor for winter was nearly 47% lower than summer EF. Open-lot corrals (~63%) in summer and (~95%) in winter were the highest contributors to NH3 emissions for the open-lot dairy. In the second study, the EFs for the free-stall dairy were determined to be 11.1 ?4.9 kg NH3 year-1 head-1 for summer season and 4.7? 4.9 kg NH3 year-1 head-1 for winter season. The estimated annual NH3 EF was 8.4 ?4.9 kg NH3 year-1 head-1 for this free-stall dairy. In winter, composted manure and free-stalls contributed nearly 73% to the total NH3 emissions for the dairy. However in summer, approximately 65% of overall NH3 emissions were contributed by two lagoons at the dairy. The overall differences between winter and summer NH3 emissions from the dairies were due to ambient temperature variations and loading rates of manure on GLAS. There was spatial variation of NH3 emissions from the open-lot earthen corrals due to variable animal density within different divisions of the open-lot. This spatial variability was attributed to dispirit manure loading within these areas.