Advising political decision-makers at the national level:

RELAS project to monitor the impact of the Fertilizer Ordinance in Germany.

Germany still has problems achieving the quality standards for nutrients valid for surface waters, groundwater as well as coastal waters, so that the good status of water resources in Germany has not yet been achieved. In 2018, the European Court of Justice condemned the Federal Republic of Germany for failing to implement the Nitrates Directive (Case C-543/16). If the situation does not improve, Germany faces fines in the order of billions of euros.

To avoid this, the German government revised the Fertilizer Ordinance in 2020. In addition, a nationwide monitoring, control and analysis system is being set up in Germany that will enable conclusions to be drawn at short intervals on the effectiveness of the measures taken. In the future, this impact monitoring will record, among other things, nitrogen emissions from agriculture and nitrate concentrations in groundwater. In the context of the impact monitoring, Germany-wide modeling of nutrient inputs will be carried out based on the model network AGRUM-DE, consisting of the models RAUMIS of the Thünen Institute, the models mGROWA-DENUZ-WEKU-MEPhos developed in IBG-3 and the MONERIS model of the Leibniz Institute of Freshwater Ecology and Inland Fisheries. The models developed in IBG-3 will help to:

  • determine runoff and the input pathways for nitrogen and phosphorus (mGROWA),
  • simulate nitrate conversion and transport in soil and groundwater as well as diffuse nitrogen inputs to surface waters (DENUZ and WEKU)
  • model the diffuse phosphorus inputs to surface waters (MEPhos).
Advising political decision-makers at the national level:

In the RELAS project, the model network is used to identify the current spatial pollution hotspots in Germany and to simulate how much nitrogen and phosphorus enters the groundwater and surface waters in a defined area. Based on this, it is assessed whether measures - such as less fertilization in agriculture - will have an impact years or even decades later, so that these measures can be readjusted in advance if necessary.

The spatially differentiated modeling of nitrogen and phosphorus fluxes in Germany is an important contribution to monitoring the effects of the Fertilizer Ordinance on water protection and also to supporting political decision-makers at EU, federal and state level with regard to achieving the groundwater protection targets under the EU Nitrate Directive and the EU Water Framework Directive as well as the protection targets for surface waters under the EU Water Framework Directive and the marine protection targets under the Marine Strategy Framework Directive.

Key points:

  • Project RELAS: Modelling of regional agricultural nitrogen fluxes as a basis for the development and optimization of agricultural policy measures.
  • Funding Institution: German Federal Ministry of Food and Agriculture (BMEL)
  • Project Management Agency: Federal Agency for Agriculture and Food (BLE)
  • Project duration: 01.09.2022 -31.08.2025
  • Project partners: Thünen Institute for Living Conditions in Rural Areas (LV) and the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB)
  • Target groups:
    • European Commission,
    • Federal Ministry of Food and Agriculture (BMEL)
    • Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV),
    • the 16 German federal states,
    • agricultural and water management authorities

contact persons:

Prof. Dr. Frank Wendland and Dr. Björn Tetzlaff

Institute for Bio- and Geosciences, IBG-3

Tel.: 0049 171 3003 594,


Last Modified: 11.07.2024