Dynamics of ammonia volatilisation measured by eddy covariance during slurry spreading in north Italy

During spring 2009 and 2011, dairy slurry was spread in two intensively managedagricultural fields in northern Italy. Ammonia (NH3) fluxes have been measured using the eddycovariance method during the slurry application and the following incorporation into the soil. Themeasurement system was equipped with a fast sensor for NH3 concentration measurements based onTunable Infrared Laser Differential Absorption Spectrometry. NH3 volatilisation has been monitored incontinuous until the end of the process for both experimental trials, confirming the rapidity of the NH3losses when slurry is spread on the field. Within 24 hours from the application the volatilisationsuddenly decreases, stopping after slurry incorporation. The maximum NH3 emission levels were138.3 and 245.5 ?g m-2 s-1 and the total losses of NH4+-N were 19.4% and 28.5% after 7 daysfollowing the spreading for the first and the second trial, respectively. To explain these observeddifferences, the relationship between NH3 losses and meteorological conditions has been investigated.In particular, rain during the 2009 trial caused a significant reduction in emissions with respect to the2011 one, which was characterised by higher air temperatures.