Temporal Stability of Spatial Patterns of Nitrous Oxide Fluxes from Sloping Grassland

Abstract

Abstract Insight into the temporal and spatial variability of nitrous oxide (N 2 O) fluxes from soils is required to set up efficient sampling protocols of N 2 O fluxes and to set up strategies to reduce N 2 O fluxes. The aim of the present study was to assess the temporal stability of the spatial pattern of N 2 O fluxes along a transect (400 m) on a fertilized sloping grassland soil. Geostatistical analyses of flux chamber measurements over 4 d showed a clear spatial dependency of N 2 O fluxes. The spatial variability of N 2 O fluxes was much higher than the temporal variability during the 4 d. Despite the decreasing magnitude of the fluxes in time, the spatial pattern persisted during 4 d, that is, fluxes were always highest at the steepest part of the transect. The 15 N natural abundance (δ 15 N) in soil N was significantly correlated with N 2 O fluxes, indicating a long‐term effect of N loss as N 2 O on the 15 N abundance in the soil. It was suggested that topography played a role in the observed spatial patterns of N 2 O fluxes and Δ 15 N in soil N. The study showed that despite the persistent spatial pattern of N 2 O fluxes, flux magnitude may strongly fluctuate in time. Therefore, it is often not possible to combine N 2 O flux measurements made at different times in order to obtain enough data for geostatistical analysis.