NITROGEN PROCESSES IN CULTIVATED PEAT SOIL - USE OF STABLE NITROGEN ISOTOPES TO DETERMINE FACTORS CONTROLLING DENITRIFICATION AND DNRA AFTER SLUDGE APPLICATION

摘要

Nitrogen processes in peat soil and pure sand, as well as the environmental factors influencing these processes have been examined using batch studies. The following environmental factors will be studied: carbon-to-electron-acceptor ratio, oxygen content and temperature. So far the influence of different oxygen concentrations has been examined. The denitrification rate was high in both materials and increased with decreasing oxygen concentrations. Only peat soil had a substantial production of N_2O. Nitrification contributed to some extent to the production of N_2O. No enrichment of NH_4 - ~(15)N was found and hence no reduction of nitrate to ammonium had taken place. The effect of varying the C/N ratio on the DNRA process is further studied in on-going experiments.