Spatial Variability of Ammonia Concentrations in an Open-Sided Dairy Barn

The variability of daily concentrations of ammonia (NH3) was assessed at different sampling locations (SLs), horizontally and vertically distributed at the centre of an open-sided dairy barn in Mediterranean climate. Concentrations of NH3 were continuously measured at 6 SLs in a cubicle free-stall dairy barn located in the province of Ragusa (Italy). Data acquired were organised in a dataset and statistical analyses were performed to delineate potential differences in gas concentration distribution. Application of a one-way analysis of variance (ANOVA) tested the equality of the mean values of gas concentrations for each group of the parameters analysed for groups of SLs. In the post-hoc analysis the mean values were separated by Tukey’s honestly significant difference at P < 0.05. NH3 concentrations changed in time and with SLs during the day inside the barn. There was a significant difference (P < 0.001) for NH3 concentrations at different SLs. In detail, the highest values of NH3 concentrations were recorded at 0.40 m from the floor where the trend of the gas showed the highest variability, whereas the lowest values of NH3 were measured at 1.55 m from the floor. At 0.40 m and 2.70 m from the floor, concentrations decreased in the prevailing air direction due to the dispersion and dilution effects. At 1.55 m from the floor, this was not confirmed due to the effect of the fans on the air flux.