Temporal stability of spatial patterns of nitrons oxide fluxes from sloping grassland

Insight into the temporal and spatial variability of nitrous oxide (N2O) fl uxes from soils is required to set up efficient sampling protocols of N2O f luxes and to set up strategies to reduce N2O fluxes. The aim of the present study was to assess the temporal stability of the spatial pattern of N2O f luxes along a transect (400 m) on a fertilized sloping grassland soil. Geos tatistical analyses of flux chamber measurements over 4 d showed a clear sp atial dependency of N2O fluxes. The spatial variability of N2O fluxes was m uch higher than the temporal variability during the 4 d. Despite the decrea sing magnitude of the flues in time, the spatial pattern persisted during 4 d, that is, fluxes were always highest at the steepest part of the transec t. The N-15 natural abundance (delta(15)N) in soil N was significantly corr elated with N2O fluxes, indicating a long-term effect of N loss as N2O on t he N-15 abundance in the soil. It was suggested that topography played a ro le in the observed spatial patterns of N2O nuxes and Delta(15)N in soil N. The study showed that despite the persistent spatial pattern of N2O fluxes, flux magnitude may strongly fluctuate in time. Therefore, it is often not possible to combine N2O flux measurements made at different times in order to obtain enough data for geostatistical analysis.