ABSTRACT
Emissions of ammonia were measured from livestock excreta and fertilisers applied to grass swards, from grazed paddocks, from decomposing grass herbage and from an animal house containing dairy cows. Emissions from urine, dung, slurry and fertilisers were determined using a system of wind tunnels with each tunnel covering an area of 1 m(2). Emissions from grazed swards were determined using a micrometeorological mass balance method. From the results of these measurements, together with other published information, an inventory for ammonia emissions has been calculated for grassland and livestock production systems over the UK as a whole. It is estimated that emissions from grassland and cattle and sheep production amount to about 230 kt NH(3)-N annually, while emissions from pig and poultry production amount to about 40 kt and 80 kt NH(3)-N, respectively.
ABSTRACT
Emission of NO(x) from urine-treated pasture was determined using a system of enclosures coupled to a chemiluminescence NO(x) analyser. Rates of emission ranged from 0 to 190 microg NO(x) - Nm(-2)h(-1), with a mean of 43 microg N m(-2) h(-1). The lowest rates were associated with periods of heavy or persistent rain. On average, NO comprised 68% of the NO(x) produced. Emissions of NO(x) were apparently associated with the nitrification of ammonium N derived from hydrolysis of organic N constituents in the urine applied. Emissions from untreated pasture occurred at a mean rate of 1.7 microg NO(x) -N m(-2) h(-1). NO(x) comprised only a small proportion (<0.1%) of the emission of other nitrogenous gases (NH(3), N(2) and N(2)O) following application of urine. The mean rate of NO(x) emission suggested a total release to the atmosphere of 2.3 x 10(-8) g N year(-1) from urine returned to pasture in the UK. This loss is not significant in agronomic terms and is equivalent to only 0.04% of the estimated anthropogenic emissions for the UK.
