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A comparison of disaggregated nitrogen budgets for Danish agriculture using Europe-wide and national approaches

Kros, Johannes, Hutchings, Nicholas J., Kristensen, Inge Toft, Kristensen, Ib Sillebak, Børgesen, Christen Duus, Voogd, Jan Cees, Dalgaard, Tommy, de Vries, Wim
The Science of the total environment 2018 v.643 pp. 890-901
European Union, agricultural statistics, excretion, fertilizers, leaching, mineralization, models, national budget, nitrogen, nitrogen fixation, plant cultural practices, pollution, runoff, uncertainty, Denmark
Spatially detailed information on agricultural nitrogen (N) budgets is relevant to identify regions where there is a need for a reduction in inputs in view of various forms of N pollution. However, at the scale of the European Union, there is a lack of consistent, reliable, high spatial resolution data necessary for the calculation of regional N losses. To gain insight in the reduction in uncertainty achieved by using higher spatial resolution input data. This was done by comparing spatially disaggregated agricultural N budgets for Denmark for the period 2000–2010, generated by two versions of the European scale model Integrator, a version using high spatial resolution national data for Denmark (Integrator-DK) and a version using available data at the EU scale (Integrator-EU). Results showed that the national N fluxes in the N budgets calculated by the two versions of the model were within 1–5% for N inputs by fertilizer and manure excretion, but inputs by N fixation and N mineralisation differed by 50–100% and N uptake also differed by ca 25%, causing a difference in N leaching and runoff of nearly 50%. Comparison with an independently derived Danish national budget appeared generally to be better with Integrator-EU results in 2000 but with Integrator-DK results in 2010. However, the spatial distribution of manure distribution and N losses from Integrator-DK were closer to observed distributions than those from Integrator-EU. We conclude that close attention to local agronomic practices is needed when using a leaching fraction approach and that for effective support of environmental policymaking, Member States need to collect or submit high spatial resolution agricultural data to Eurostat.