Abstract: Field studies were conducted to assess the spatial and temporal variability of nitrous oxide (N2O) emissions in an agricultural field cropped to onion in Mikassa, northern Hokkaido (Japan). N2O emissions measurements were conducted in 100 by 100 m and 60 by 60 m grids in 1999 and 2000, respectively with samples taken at 10 m spacing. Air samples for N2O determinations were collected using the closed-chamber technique. The chambers were circular with steel frames. The top of each chamber had a gas sampling tube and a bag to control air pressure inside. The height and diameter of the chamber were 0.35 and 0.30 m, respectively. Air samples were stored in vial bottles for analysis with a gas chromatograph with electron capture detector within 24 h after sampling. GS+ 7.0 geostatistical software and statistix 8.0 were used for data analysis. Results showed that N2O emissions were highest in 1999 as compared to 2000. N2O emissions were fitted to a linear variogram in 1999 and responded to a spherical variogram model in 2000. Positive first degree surface trends were also found for N2O emissions data in both years. However, the removal of these trends did not change variogram models, but significantly improved them by increasing the R2 and Q values. N2O emissions systematically varied with small zones of uptake (negative flux) across the field, suggesting the presence of hot spots.