Multi-location measurements of greenhouse gases and emission rates of methane and ammonia from a naturally-ventilated barn for dairy cows

Measurements of the gaseous emissions in livestock buildings are important as these pollutants may affect the health of farmers and the surrounding environment. Emission monitoring enables judgements on the effectiveness of mitigation strategies and controls on emission targets. The concentrations of CH4, N2O, NH3 and CO2 were measured in a naturally-ventilated dairy cattle building using a photoacoustic multi-gas analyser 1412 and a multiplexer 1309 (Lumasense Technologies SA, Ballerup, Denmark). The building had 164–195 Holstein dairy cows. The milk production was 31–33 kg cow−1 d−1. Manure gutters beneath the partially slatted floor in the building were scraped twice a day. Measurements took place during the winter when the cows were permanently indoors and during 1 week in the spring when the cows were indoors at night and outside grazing during the daytime. The indoor concentrations were measured at nine evenly distributed locations, while outdoor concentrations were measured at two locations. The mean ventilation rate in winter was 250–265 m3 LU−1 h−1 and in spring, it was 401 m3 LU−1 h−1. The emissions of NH3 and CH4 were in the range of 0.89–1.13 and 9–13 g LU−1 h−1, respectively. A strong positive correlation was found between enhanced CO2 and CH4 concentrations.