Manure ammonia and hydrogen sulfide emissions from a Western dairy storage basin.

The reporting of ammonia (NH) and hydrogen sulfide (HS) emissions from dairies to the federal government depends on the magnitude of the emissions. However, little is known about their daily NH and HS emissions and what influences those emissions. Emissions of NH and HS from two manure storage basins at a 4400-head western free-stall dairy were measured intermittently over 2 yr. Each basin went through stages of filling, drying, and then removal of the manure during the study period. Emissions were determined using backward Lagrangian Stochastic and vertical radial plume methods. Ammonia emissions ranged from 35 to 59 kg d in one basin and from 86 to 90 kg d in a second basin, corresponding to a range of 7 to 19 g d head. Basin NH emissions were highest during initial filling and when the manure was removed. Mean HS emissions ranged from 5 to 22 kg d (1.1-4.6 g d head). Basin HS emissions were highest when the basin was filling. Crusting of the basin surface reduced NH but not HS emissions. The cessation of basin filling reduced HS but not NH emissions. Air temperature and wind conditions were correlated with NH emissions. Barometric pressure decreases were correlated with episodic HS emissions. The variability in emissions with stage of manure handling and storage and meteorological conditions indicates that determining the maximum daily emissions and the annual emissions from such waste basins requires consideration of each stage in conjunction with the climatic conditions during the stage.