Nitrous oxide (N₂O) is an important greenhouse gas and the major stratospheric ozone-depleting substance; therefore, mitigation of anthropogenic N₂O emissions is needed. To trace N₂O-emitting source processes, in this study, we observed N₂O isotopocules above an intensively managed grassland research site with a recently developed laser spectroscopy method. Our results indicate that the domain of denitrification or nitrifier denitrification was the major N₂O source.