Gaseous emissions from outdoor concrete yards used by livestock

Measurements of ammonia (NH3), nitrous oxide (N2O) and methane (CH4) were m ade from 11 outdoor concrete yards used by livestock. Measurements of NH3 e mission were made using the equilibrium concentration technique while close d chambers were used to measure N2O and CH4 emissions, Outdoor yards used b y livestock proved to be an important source of NH3 emission. Greatest emis sion rates were measured from dairy cow feeding yards, with a mean of 690 m g NH3-N m(-2) h(-1). Smaller emission rates were measured from sheep handli ng areas, dairy cow collecting yards, beef feeding yards and a pig loading area, with respective mean emission rates of 440, 280, 220 and 140 mg NH3-N m(-2) h(-1) . Emission rates of N2O and CH4 were much smaller and for CH4, in particular, emission rates were influenced greatly by the presence or ab sence of dung on the measurement area. (C) 2001 Elsevier Science Ltd. All r ights reserved.