A DIRECT INCORPORATION OF N-15 LABELED AMMONIUM-SULFATE INTO A PIG SLURRY - A LABORATORY EXPERIMENT ON NH3 VOLATILIZATION

The addition of exogenous ammoniacal nitrogen to slurry can be used to study the influence of ammoniacal nitrogen concentration or the prese nce of different ions on ammonia emissions. This preliminary study aim ed to test the validity of such a direct incorporation of ammonium sal ts to slurries in relation to ammonia volatilization. It was conducted using cylindrical glass volatilization chambers and N-15-labelling te chniques. Labelled pig slurry was prepared by direct addition of N-15- (NH4)2SO4 (N-15-AS). The fate of total ammoniacal nitrogen was followe d for 48 h from surface application to soil. The analysis of isotopic excess (E%) of volatilized ammonia 0.25, 2, 6, 12, 24 and 48 h after l abelled slurry application suggested that the added N4+ behaved as the endogenous NH4+ initially present in the slurry. An average TAN-N-15 (total ammoniacal nitrogen) recovery of 97.5% (CV 2%) was obtained. Du ring this study, no immobilization or nitrification of slurry-derived nitrogen was noticed.