Nitrous oxide (N2O) contributes substantially to greenhouse gas (GHG) emissions in the agricultural and landuse
sectors. Owing to the high effort needed for measuring N2O emissions and the resulting lack of sufficient field measurements to apply at country-wide scale, soil-borne N2O emissions are often estimated by applying published IPCC default emission factors. To examine the data reported in the national GHG inventory, the current study utilizes a large data set of soil C/N ratios to predict N2O emissions and their distribution from drained organic soils in Switzerland. Calculated emission rates increase in the order of forest < grassland < cropland, and they are similar to the mean values currently used in the inventory. Distributions of N2O emissions are highly
positive-skewed and they reveal probabilities of 10 and 14% for cropland and grassland, respectively, to be above 20 kg of N2O-N per hectare and year. It is likely that the greater part of N2O from drained organic soil derives fromNreleased upon peat decomposition, and not fromfertilization. In conclusion, this research shows that measurement of soil C/N ratios improves the reliability of organic soil N2O emissions estimates on a national scale and identifies site conditionswhere future emissionmeasurementswould be most effective for reducing the uncertainty
in the GHG inventory.