LAUSR

Dairies contribute a major portion of agricultural ammonia emissions in the United States. Emissions were monitored over two years from an anaerobic lagoon receiving manure from cows in the milking parlor and holding area in Indiana (IN), USA and a storage basin receiving manure from cows in barns as well as the milking parlor and holding area in Wisconsin (WI), USA. Emissions were monitored using open-path tunable diode lasers, sonic anemometers, and two emission models. The mean annual daily emissions at the WI storage basins (30 µg m−2 s−1) was nearly equal to that at the IN lagoon (27 µg m−2 s−1). The mean annual daily ammonia (NH3) emissions on a per animal basis were greater at the WI basins (33 g NH3 hd−1 d−1; 26 g NH3 AU−1 d−1) (hd = animal; AU = 500 kg animal mass) than at the IN lagoon (9 g NH3 hd−1 d−1; 7 g NH3 AU−1 d−1). Emissions from both storage systems were highest in the summer, lowest in the winter, and similar during the spring and fall. Emissions were strongly correlated with air temperature and weakly correlated with wind conditions. Greater emissions at the WI basins appeared to be related primarily to the characteristics of the stored manure.