Agriculture intensification and diversification could increase N₂O emissions from Uruguayan soils, but due to the lack of local data, there is a high uncertainty on current estimations for the country, because they are based on mean IPCC factors. N₂O emission rates were measured from August 2003 to September 2004 on two contrasting sites of southwest Uruguay. One of the sites was a long-term experiment established on a high fertility agricultural soil, with two tillage practices (no tillage= NT and conventional tillage=CT) and crop rotations (continues agriculture=CA or rotation with planted pastures=RP). The other site was a recently-harvested eucalypt plantation, located on a lower fertility soil. In both cases, a permanent natural pasture was used as a control. N₂O soil fluxes were measured on an event-driven basis using the closed chamber technique with 6 replicates per treatment. On an annual basis, emissions from both the agricultural and the eucalypt-harvested soils were significantly higher than those from their respective natural pastures (3.39 and 2.79 vs. 0.64 and 0.22 kg N-N₂O ha^-1 y^-1, respectively). Differences within treatments in the agricultural soil, however, were minor and most of the time statistically non-significant, but there was a tendency toward higher N₂O emissions from the CT-CA and NT-RP treatments. Spatial variability was very high in all treatments and in both soils, indicating the high natural variability of N₂0 fluxes from soils, probably as a consequence of the various physical, chemical and biological factors controlling this emission. The highest fluxes, however, were associated with periods of relatively high soil moisture contents and/or high soil temperatures. Overall, these results suggest that land use change from natural pastures to either agriculture-pasture rotations or tree plantations could have a large impact on N₂O emissions from Uruguayan soils.