Comparison of land nitrogen budgets for European agriculture by various modeling approaches

A comparison of nitrogen (N) budgets for the year 2000 of agro-ecosystems is made for the EU 27 countries by four models with different complexity and data requirements, i.e. INTEGRATOR, IDEAg, MITERRA and IMAGE. The models estimate a comparable total N input in European agriculture, i.e. 23.3–25.7 Mton N yr−1, but N uptake varies more, i.e. from 11.3 to 15.4 Mton N yr−1 leading to total N surpluses varying from 10.4 to 13.2 Mton N yr−1. The estimated overall variation at EU 27 is small for the emissions of ammonia (2.8–3.1 Mton N yr−1) and nitrous oxide (0.33–0.43 Mton N yr−1), but large for the sum of N leaching and runoff (2.7–6.3 Mton N yr−1). Unlike the overall EU estimates, the difference in N output fluxes between models is large at regional scale. This is mainly determined by N inputs, differences being highest in areas with high livestock density.

► N budgets of agro-ecosystems are derived for EU 27 for the year 2000 by four models. ► The models estimate a comparable total N input at EU27 but country inputs vary more. ► Variation at EU 27 is small for NH3 and N2O emissions but N2O country values vary much. ► The sum of N leaching and runoff varies twofold at EU27 level and needs more attention.