Ammonia and methane emissions from two naturally ventilated dairy cattle buildings and the influence of climatic factors on ammonia emissions

Based on the requirement of the international conventions, there is a pressing need for inventory of NH3, CH4, CO2 and N2O emissions from livestock buildings. The main aim of this study was to quantify the gas emissions and investigate the influence of the climatic factors on ammonia emissions. The measurements were carried out in two naturally ventilated dairy cattle buildings with different layouts, floor types and manure management systems during three periods covering winter and summer time. Air temperature and the three dimensional air velocities inside and outside the buildings were recorded over the course of summer period. Emission rates were determined by CO2 production model. sults showed that the internal concentrations of NH3, CH4 and CO2 were increased or decreased simultaneously. Low concentration of N2O was measured outside and inside the buildings; the difference of the concentrations were also very low. The variation of CH4 and CO2 concentrations showed a strong correlation. The NH3 emission rates varied from 32 to 77 g HPU−1 d−1 in building 1 and varied from 18 to 30 g HPU−1 d−1 in building 2. The average emission of CH4 was 290 and 230 g HPU−1 d−1 from building 1 and 2, respectively. Diurnal pattern was found for NH3 and CH4 emission rates. From multiple linear regression models, there was a significant linear relationship between NH3 emission rates and climatic factors including the external wind speed as well as the air temperature (P < 0.001), but not with the external wind directions (P > 0.05).