Loss of nitrogen through ammonia volatilisation during and following the application of pig or cattle slurry to grassland

Abstract

AbstractThe micrometeorological mass balance method was used to determine ammonia (NH3) volatilisation following the application of pig or cattle slurry to grassland at sites in the UK and The Netherlands. This method involved the measurement of wind speed and the concentration of NH3 in air at 5 or 6 heights above a treated area; the results were compared with those from a simpler method, which required measurements at only one height. In addition, measurements were made of the amounts of NH3 lost from slurry whilst it was being spread on land with a conventional tractor‐drawn vacuum tanker. Some of the factors influencing volatilisation were examined. Losses of NH3N after spreading were equivalent to between 5 and 27% of the total nitrogen (TV) applied in pig slurry and to 23% for a single experiment with cattle slurry. Despite smaller application rates, losses were greater in The Netherlands than in the UK, apparently because of differences in slurry composition. Losses during spreading represented less than 1% of the total over a 3‐day period. Up to 85% of the total loss of NH3‐N occurred within 12 h of application, the highest rate of loss (12.1 kg NH3‐N ha−1 h−1 being recorded immediately after the application of pig slurry in The Netherlands. Results from the single height method were not significantly different from those obtained by the mass balance method.