4.3.3. N2O flux during the flooded growing period
To date, few studies have reported the diurnal pattern of N2O fluxes from a rice paddy (see
Chapter 4.8.1). Hou et al. (2000) reported that N2O fluxes during the flooded growing period
were higher in the daytime and lower in the nighttime, like the diurnal pattern of the CH4 flux.However, our preliminary analysis of N2O flux data measured by the automated closed
chamber method in Japan did not show any typical diurnal pattern (Figure 4.3). The lack of a
consistent pattern is partly attributable to the application level of N, which is conventionally
low in Japan generally (in this field it was 90 kg N ha–1). Therefore, we recommend measuring
the N2O flux at the same time as the CH4 flux, that is, in mid-morning. For measurement
during temporary drainage, see Chapter 4.4.2.