DENITRIFICATION AND THE EVOLUTION OF NITROUS-OXIDE AFTER THE APPLICATION OF CATTLE SLURRY TO A PEAT SOIL

The impact of cattle slurry on denitrification losses and nitrous oxide emission was determined on a peat soil in the Netherlands. As well as measuring losses on a day-to-day basis after three different methods of slurry application, two methods for estimating denitrification and nitrous oxide emissions were compared, i.e. coring/incubation and enclosure techniques. Slurry was applied either in a conventional way, diluted 1:3 or acidified with nitric acid. There was much variation with time, method of assessment and method of slurry application in both apparent denitrification rates and N2O fluxes: it was not always possible to provide adequate explanation for all of the effects demonstrated. Major proportions of the variation in denitrification and N2O emission could be accounted for by variation in soil moisture, soil temperature and NH4+ (but not NO3-) content. It was suggested that nitrification was playing a key role in maintaining an adequate substrate supply (NO) for denitrification and perhaps contributing directly to an unknown extent to N2O emissions. There were overall differences in the extent of losses with the different methods of slurry application but these were highly dependent upon interactions with current soil and weather conditions.