N2O Emission Factors for Italian Crops

At each site, the total amount of N₂O emitted at each single fertilization event was quantified by linear interpolation between sampling dates following the event till the flux reached a steady value close to the pre-fertilization level. The latter was instead defined as baseline flux and the fertilizer induced emission (FIE) was then calculated as the difference between the total flux minus the baseline flux. The corresponding EF was finally computed as the ratio between FIE and the amount of N added at the considered fertilization event.

Results show that for this specific crop, with its growing season in spring-summer, hence when the combination of temperature and rain regime mostly differs from non Mediterranean climate areas, the calculated emission factors were lower than the average emission factor reported by IPCC (2006) for temperate agricultural soils (1 %) (EFs reported in Table 9.2), with the exception of the Turin site (site 7 and 8). The overall mean EF was 0.7 % ± 2.3 (2 SD) and 0.3 % ± 0.4 (2 SD) including or excluding this site from the analysis, respectively. For a better characterization of the magnitude of N₂O emissions, the total fertilizer induced emission (FIE), the maximum peak value and the time length of the emission peak (back to baseline) were calculated (Table 9.2