Nitrous Oxide Emissions from Arable Soils of Europe: a Multi-Decadal Analysis Using the Biogeochemical Model LandscapeDNDC

Arable soils are considered to be strong terrestrial sources of nitrous oxide (N2O) emissions. European countries have a long history of intensive fertilizer use, which leads to substantial gaseous and aquatic nitrogen losses. Biogeochemical models like LandscapeDNDC were designed to simulate relevant processes and pools of the carbon and nitrogen cycle and their environmental controls. We present direct and indirect N2O emission estimates for arable soils of Europe as calculated by the new LandscapeDNDC model and based on the NitroEurope database. Emissions were calculated for 21,467 spatial units and daily climate data (1971-2000). Five model runs were conduced to capture variability of arable management practices. The mean N2O emission for arable soils of Europe was 2.2 kg N ha-1 yr-1 (307,239 t N yr-1 for the entire area of 1,394,442 km2). Using the IPCC guidelines for national greenhouse gas inventories, indirect emission of N2O from simulated nitrate leaching was derived. Using this simple approach, another 0.4 kg N ha-1 yr-1 were estimated to enter the troposphere (15.2% of the total N2O emission). According to our model runs, total N2O emissions from arable soils in Europe gradually increased until the early 80s, before declining back to the previous levels while N application remained high (fig.1). Regional climatic conditions, soil properties and management also strongly affect N2O emissions (see fig.2). Furthermore, intra-annual variability can be observed (not shown). The results illustrate the advantage of using mechanistic models when assessing N2O emission characteristics versus conventional up-scaling techniques.