The Effect of Microclimatic Conditions on Ammonia Emissions from an Open-Sided Dairy Barn During Spring

The aim of the study was to assess the influence of microclimatic conditions on ammonia (NH3) emissions in an open dairy barn during spring in Mediterranean climate. Measurements were carried out in a cubicle free-stall dairy barn located in the province of Ragusa (Italy) from 7th to 21st June 2016. Concentrations of NH3 as well as carbon dioxide (CO2) were continuously measured by a photo-acoustic analyser. Measurements of microclimatic variables (i.e., temperature, relative humidity, wind speed, and wind direction) were acquired by sensors installed inside the barn. The CO2 mass balance method was applied in order to estimate NH3 emissions. Data collected were organised in a dataset to carry out statistical analyses on gas emissions for groups of days characterised by different climatic parameters. The first group (G1) was characterised by higher values of the parameters compared to the second group (G2). The one-way analysis of variance (ANOVA) and correlation analyses were applied in order to identify significant differences for tested groups and relations among them. In the post-hoc analysis the mean values were separated by Tukey's honestly significant difference at P < 0.05. NH3 emissions in G1 were significantly different from those in G2 with higher NH3 emissions in G2. An almost constant trend was found for NH3 emissions in G1. During G2, the correlation between emissions and air temperature was equal to −0.67 (p < 0.001), whereas NH3 emissions showed a different trend based on air velocity. The results of this study highlighted that NH3 emissions in open structures were influenced by both microclimatic variables and barn management.