Ezequiel Miola1, Philippe Rochette2, Denis Angers3, Martin Chantigny4, Marc-Olivier Gasser5, David Pelster6, Normand Bertrand6 and Celso Aita1, (1)Federal University of Santa Maria, Santa Maria, Brazil (2)Soils and Crops Research and Development Centre, Agriculture & Agri-Food Canada, Quebec City, QC, CANADA (3)Quebec Research and Development Centre, Agriculture & Agri-Food Canada, Québec, QC, Canada (4)Soils and Crops Research and Development Centre, Agriculture & Agri-Food Canada, Quebec, QC, CANADA (5)Institut de recherche et de developpement en ago-environnement, Quebec City, QC, Canada (6)Agriculture & Agri-Food Canada, Quebec City, QC, Canada
Ammonia (NH3) volatilization was measured following soil-surface application of poultry manures obtained from contrasting handling and storage systems using wind tunnels and semi-open chambers. Our objectives were 1) to quantify NH3 losses from poultry manures typical of Eastern Canada poultry farms, 2) to relate emissions to manure properties, and 3) to compare volatilization estimates using wind tunnels and semi-open chambers. Broadcasting poultry manures resulted in NH3 losses accounting for 13 to 35% of total manure N. Compared to wind tunnels, the use of semi-open chambers for measuring volatilization losses results in two types of estimation biases. The instantaneous NH3 emission rates were strongly underestimated (70%) as a result of the slow diffusion-based gas exchange in the semi-open chamber headspace. This underestimation could be at least partially corrected by mechanical air mixing using fans. We also found that the more humid conditions inside the semi-open chambers enhanced the mineralization rate of manure nitrogen, thereby increasing the NH4-N concentration and the NH3 emissions. Therefore, the differences between the wind tunnel and chambers estimates varied depending on the manure properties (organic N content) and the length of the measurement period; stressing the importance of including contrasting manures and describing temporal volatilization dynamics in future studies comparing chamber methods. We conclude that land application of poultry manures can be a large source of NH3, that cumulated volatilization losses are proportional to their ammonium-N content and that semi-open chambers provide strongly biased estimates of NH3 losses.