Biochar amendment of soil has positive effects on soil physical properties, on the C-sequestration potential and the N-cycle as it changes the nitrification and denitrification dynamics. These changes could affect the N2O emissions. This is particularly important as N2O is a climate relevant greenhouse. Understanding the dynamics of N2O production in soil and its adaptations due to the incorporation of biochar is crucial. Stable isotope techniques using 15N and 18O were recently found to be essential in determining these N2O dynamics and new laser based cavity ring down spectrometric (CRDS) methods have become available. This enables us to systematically investigate the different processes behind N2O production. Therefore, in a laboratory based experiment we investigated the sources of N2O emissions using soils from a field experiment where biochar had been incorporated five years prior to the laboratory experiment. Soil samples of different biochar treatments were analysed by stable isotope analysis. Isotope ratio mass spectrometry (IRMS) was performed on 15N labelled soil samples and N2O fluxes were measured with a LGR (CRDS) Isotopic N2O Analyzer. In this study, there were no significant differences in the nitrous oxide fluxes, nitrification rates and N turnover rates between the biochar treatments and our control plots. This suggests that five years after biochar application, there was no significant effect of biochar on the mechanisms underpinning N2O emissions in this arable soil. Moreover, gross nitrification rates observed were higher than net nitrification rates suggesting large dinitrogen losses from the system. However, the proportion of N2O derived from denitrification was found to be substantially lower than the N2O emissions from nitrification, which could imply efficient denitrification under aerobic soil conditions. Due to the very limited amount of long-term studies on biochar correlation to N2O emissions, more research is needed on its effects.