Ammonia emissions from anaerobic treatment lagoons at sow and finishing farms in Oklahoma

Ammonia emissions were measured periodically for two years at manure treatment lagoons at sow and finishing facilities in Oklahoma. Path-integrated ammonia concentrations were measured around both lagoons using tunable diode lasers. Emissions were calculated from these concentrations and measured air turbulence statistics using a backward Lagrangian stochastic model. The maximum summer emissions were approximately 16 g m−2 s−1 (135 g d−1 hd−1) (hd = head or 1 animal) at the sow lagoon and 5 g m−2 s−1 (39 g d−1 hd−1) at the swine finishing lagoon. Winter emissions were non-zero and likely a result of barn effluent entering the lagoon on top of the frozen surfaces. Average daily emissions from the two lagoons were similar when normalized by animal mass, with annual average daily mean emissions of 130 g d−1 AU−1 ± 72 g d−1 AU−1 (1 animal unit, AU = 500 kg) and mean summer average daily mean emissions of 285 ± 71 g d−1 AU−1. A semi-empirical model based on daily mean air temperature and daily mean wind speed accounted for 75% of the daily emission variability at the two lagoons.