Estimates of Ammonia Emission from Dairy Cow Collecting Yards

Abstract

Two approaches were used to estimate ammonia (NH3) emission from dairy cow collecting yards. In the first, a system of small wind tunnels was used to estimate emission from urine spread on small concreted areas dirtied with faeces and to identify some of the factors controlling the extent of the loss. In the second, a hood was used to measure emission per unit area from a collecting yard on a commercial dairy farm. Mean emission from urine applied to concrete in the wind tunnel experiments was 49% of the applied urea-N. Cleaning concreted areas reduced emission, with mean emission of applied urea-N of 25 and 36% if concrete areas were scraped at 2 or 6 h, respectively. Hosing the concrete was more effective at reducing emission, but considered to be less typical of practice on UK dairy farms. Mean emissions from the collecting yard on the commercial dairy farm accounted for 93 and 40% of urea-N input to the yard for summer and winter, respectively, the lower winter emissions possibly being due to a combination of lower urea-N input to the yard and lower temperature. An average emission factor estimated from the hood measurements was 8·3 g N/cow d. Inclusion of this emission factor in a recent inventory of NH3emission from UK agriculture, increased the estimate of annual emission per dairy cow by 11%, showing it to be a significant source which may not have previously been accounted.