Ammonia emission from stored dairy manure and its local deposition

It is recognized that livestock facilities with exposed manure are hotspots of volatilized ammonia (NH3) and a significant point of entry for nitrogen (N) into the environment. The release of NH3 into air alters atmospheric chemistry, contributes to poor air quality and is of environmental concern as it is deposited to land and water down wind of the source. The objective of our study was to document NH3 emissions from a dairy lagoon, assess the influence of meteorology on emissions, and consider the local deposition of NH3. Ammonia emissions were determined using a backward Lagrangian Stochastic approach using WindTrax software, open-path lasers and sonic anemometers.

Results indicate that an average of 5.1 g NH₃ m^-2 d^-1 was released over the summer with emissions varying between 3.6 and 8.6 g NH₃ m^-2 d^-1.

The most significant meteorological parameters affecting NH3 emission were wind speed and surface temperature that accounted for 28 and 31%, respectively, of the variability in lagoon emissions. It is estimated that 18.6% of the released NH3 was deposited within 50 m of the lagoon. The main implication of this study is that NH3 losses are significant from dairy lagoons. However, it is speculated that local N deposition will not negatively impact agricultural land that is generally deficient in N for crop growth.