Key points are not available for this paper at this time.
Spatial heterogeneity of the N 2 O emission activity was characterized at a fertilized grassland by means of small chambers arranged in grids with spacings ranging from 0.11 m to 7.1 m. The fluxes exhibited marked spatial variability, approximately lognormally distributed. The variation decreased (1) over time within the 7.1‐m grid, (2) when grid size was reduced, and (3) after glucose amendments. This decrease was probably caused by homogeneous soil aeration (1) when soil drains, (2) within minor areas, and (3) when overall soil respiration was enhanced by glucose. Isotropie semivariograms showed spatial autocorrelation of N 2 O fluxes beyond separations of 7.1 m and below those of 0.8 m. The small‐scale autocorrelation disappeared in response to glucose. Substantial variation occurred below the scale of minimum separation. High local N 2 O fluxes at an 1.8‐m resolution were coincident with wet depressions in the ground. We suggest that N 2 O flux patterns at the scale beyond 7 m was controlled by soil moisture variability governed by ground topography, whereas a patchy distribution of denitrifying microsites governed N 2 O emission at the scale below 1 m. The study indicates that even N 2 O fluxes obtained from “megachambers” (upward of 50 m 2 ) should be interpreted carefully since they may not encompass the whole field variability.
Ambus et al. (1994) studied this question.