Preliminary results on the influence of emptying slurry pits on the emission of ammonia and odours from fattening buildings

The aim of this study was to determine the influence of emptying slurry pits on odour and ammonia emissions from fattening buildings. The experiment was conducted at the ITP experimental station at Romillé. Three identical finishing rooms were used in this study : the first one acted as the reference, where slurry was stored throughout finishing period, in the second room, slurry was removed every 15 d, while in the third room slurry was removed once during the fattening period.Chemical and olfactometric analyses were performed on air extracted from the finishing rooms and ambient ammonia concentrations were measured. Growth performance was identical in the three rooms. Odours emitted by the two rooms where slurry was removed, was not reduced in comparison with the reference room. However, emptying slurry every 15 days had an effect on ammonia emitted (-20%) compared to the room where the pits were not emptied. This effect could be explained by the greater volume of air under the slatted floor in the room where the pits were emptied frequently, which may have limited the contact between slurry and the air evacuated from the room. This would reduce the volatilisation of ammonia. The finding that odour emission was not reduced is probably linked to the observation that part of the solid fraction of slurry remains in the pit even after emptying.