Vertical Profile of Noxious Gas Concentrations in an Open Dairy Barn in Mediterranean Area

The aim of the study was to investigate the vertical profile of ammonia (NH3), methane (CH4) and carbon dioxide (CO2) at different sampling locations (SLs) at the centre of an open dairy barn located in the Mediterranean area. The experiment was carried out in a cubicle free-stall dairy barn equipped with fans, located in Sicily (Italy). The photo-acoustic spectroscopy was applied to record NH3, CH4 and CO2 at three sampling locations. The SLs were vertically distributed at the centre of the barn. Gas concentrations at different heights (i.e. sampling location A, sampling locations B and sampling locations C at 0.40 m, 1.50 m and 2.70 m, respectively) from the floor were organised in a dataset and statistical analyses were carried out to identify differences in gas concentration profiles among the considered gases. Data were examined by using the one-way analysis of variance (ANOVA), correlation analysis, and regression analysis. The vertical profile of gas concentrations showed significant differences between gases (P < 0.001). The highest values for NH3 and CH4 were recorded at 0.40 m and 2.70 m from the floor, respectively. The correlation coefficient between NH3 at SLB and NH3 at SLC, CH4 at SLC and CO2 at SLC, and CH4 at SLC and NH3 at SLC ranged between 0.46 and 0.71, with the lowest values for NH3 and CH4 correlations at the lower SLs. Based on the regression analysis, the R-squared adj between NH3 at SLB and NH3 at SLC as well as CO2 at SLC and CH4 at SLC was higher than 40% with P < 0.05.