Rebalancing nutrient flows in Europe’s agricultural heartland

The Rhine, Meuse & Scheldt Basin in the lowlands of Belgium and the Netherlands is one of GREENHOOD’s most critical demo-regions. Characterised by high population density and some of the most intensive farming systems in the world, the basin features the highest livestock density in Europe. This concentration, combined with an intricate network of drainage channels, creates severe nutrient pressures on both surface and groundwater. Currently, many surface water bodies across the region struggle to meet the quality standards required by the EU Water Framework Directive (WFD), largely due to eutrophication driven by nutrient overloading. In the period 2023-2024, 17.5% measuring points of surface waters had at least one exceedance of the WFD limit of 50 mg nitrate/L (Flemish government, 2025).

Current status

Agriculture is the primary source of nutrient residual flows in the region. The basin faces a persistent structural surplus of nitrogen and phosphorus driven by concentrated animal production and a heavy reliance on imported feed and fertilisers.

• Intensive livestock & arable pressures 
  In the Scheldt basin, agriculture accounts for 78% of reactive nitrogen and 32% of phosphorus emissions (Vingerhoets et al., 2021). In the Netherlands, emissions from agricultural fields via groundwater, tile drainage and overland flow contribute about half of the total nutrient load to surface waters.  
• Diverse transport pathways 
  Nitrogen is primarily lost through nitrate leaching into groundwater and ammonia volatilisation from manure storage and application. Phosphorus transport is driven by surface runoff, erosion, and legacy accumulation in topsoils from decades of over-application.
• Weather vulnerability 
  Nutrient losses are highly dependent on hydrology. High rainfall increases leaching and drainage losses, making the region vulnerable to climate-induced increases in eutrophication.

Current responses

Both Belgium and the Netherlands have implemented rigorous policy frameworks to address these challenges. Flanders operates under the Manure Decree (Mestdecreet) and Manure Action Plans (MAP7), enforcing zone-specific restrictions based on local water quality. The Netherlands is currently preparing the 8th Nitrate Action Programme (NAP) and is navigating the phase-out of its EU derogation, which previously allowed higher nitrogen application limits.

In practice, across the basin, stakeholders are deploying a mix of technological and agronomic solutions.

• Technological infrastructure 
  Mechanical separation (screw presses, centrifuges) and anaerobic digestion are broadly implemented to manage manure and produce renewable energy.
• Agronomic best practices 
  Farmers are adopting the "6R principle" of precision fertilisation, focusing on the right dose, product, time, and placement. Mandatory catch crops and non-fertilised buffer strips are also standard requirements to reduce runoff.

Despite these efforts, significant bottlenecks remain. Overlapping legal frameworks create administrative complexity. Furthermore, land scarcity and high land prices in these densely populated countries make the large-scale implementation of certain Nature-Based Solutions (NBS) both difficult and expensive.

Where GREENHOOD steps in

The GREENHOOD work in the Rhine, Meuse & Scheldt demo-region is co-coordinated by Ghent University and Deltares. The project addresses regional challenges by validating decentralised NBS and using REcovered Nitrogen from ManURE (RENURE) products in combination with precision fertilisation techniques. The project has established four distinct pilot catchments to test these innovations:

1. Luikbeek (Belgium): Implementing a free water surface Constructed Wetland (CW) on a 0.5 ha plot to reduce nitrate concentrations from Luikbeek water stream.
2. Aalter (Belgium): Application of ammonium sulphate as a RENURE product in combination with precision agriculture practices on a 9 ha agricultural field, aimed at evaluating its potential to substitute conventional mineral fertilisers and to reduce nitrate losses to groundwater and surface waters.
3. Vragender-Lievelde (Netherlands): Focusing on capturing nutrients using sedimentation pools and integrated buffer zones to retain and recycle nutrients in the area and reduce nutrient loads to downstream regions.
4. Vinkenloop (Netherlands): Focusing on the application of woodchip bioreactors and sedimentation pools to retain nutrients coming from tile drainage and reduce the nutrient load to the nearby stream.

In addition to physical pilots, GREENHOOD is exploring the potential of by-products coming from these NBS, such as biomass from constructed wetlands, woodchips, and sediments. These will be characterised for their physicochemical properties to discuss their potential use as nutrient sources.