River catchments are exposed to a range of stressors, whether that be wastewater, chemical contamination, or agricultural pollution. Soil management directly affects the water quality in nearby water systems, with nutrients accumulating throughout the catchment as the water drains through the soil.
The Sustainable Nitrogen Alliance recently hosted our first public panel at Groundswell 2024, discussing what farmers can do to reduce their impact on the river catchment, the wider environment and human health, while benefiting from reduced input costs.

Groundswell is a regenerative farming festival, bringing together environmental NGOs, solution-focused agribusinesses and farmers from across the agroecological spectrum. The event features talks, forums and discussions from leading soil health experts, experienced farmers, policy experts and agri-tech innovators.
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The festival is a space for new ideas and solutions to be presented and debated. In the Soil Association tent, our session was no different. The panel consisted of Tom Stuart (WWF), Emily Hunter (Woodland Trust), Alex Adam (Rivers Trust) and Heather Whalley (Ribble Rivers Trust), who used the hour to demonstrate the wide-ranging negative impacts of excess nitrogen in the environment and the solutions to mitigate those harms.
Tom started off with an introduction to the nitrogen cycle, why nitrogen is used and when it can become harmful to humans and nature. He introduced the Nitrogen Balance Sheet (NBS), recently commissioned by WWF and the SNA, which demonstrates the flows of nitrogen across the economy. Through the NBS, we can see the volume of new reactive nitrogen being introduced to soils each year through mineral (synthetic) fertiliser, nitrogen fixation, nitrogen deposition and animal manure and slurry. The low rates of reactive nitrogen cycling mean vast amounts are being lost to the environment as pollution through runoff & leaching, emissions to the atmosphere and denitrification.

The session on nitrogen drew a large crowd.
The impacts of nitrogen pollution are wide-ranging, as Emily outlined; nitrogen-driven air pollution impacts human health through heart and lung disease and is linked to some cancers. Biodiversity in sensitive habitats is reduced as plants that thrive in nitrogen-heavy environments outcompete more specialist species, such as in river systems where excess nitrogen drives algal blooms.
As demonstrated by the NBS, the largest nitrogen loss from soils is to the water system. Although size of flow does not dictate the size of impact, it is evident that the sheer volume of nitrogen ending up rivers across the country is causing damage to river health. Excess nitrogen in water systems drives eutrophication, when algal blooms deplete oxygen levels by blocking out the sun.
Alongside phosphates from sewage, nitrogen from agricultural sources is the primary driver of declining river health with only 14% of England’s rivers in ‘good’ ecological health.
Nitrogen ends up in rivers when it is washed off the soil after heavy rainfall, or through leaching into the groundwater if applied in excess of the plants needs or at a time when it is not needed for growth. Farmers losing nitrogen from their soils also represents a financial loss of resource, so it is in their best interest to avoid this. Alex introduced the idea of catchment management – that farmers could work together in a catchment to ensure practices don’t cause nutrients to enter the river at a rate that exceeds what the river’s ecosystem can sustain, while maintaining profitable yields.
Further, Alex suggested that water companies could better support farmers to introduce practices that reduce pollution. Currently, this is prohibited by the Government as the farmers are technically under the jurisdiction of Farming Rules for Water. But as these regulations aren’t currently enforced, farmers could be receiving support from water companies.
Finally, Heather advocated for farmers to take better care of their soil. Building up soil health not only keeps nutrients in the soil, but also increases flood risk management and resilience to heatwaves. When asked how we can bring farmers onboard with these solutions which may cost more in the short run, Heather suggested starting with a small ‘win-win’ that would show a farmer benefits on their farm but also in their bank balance. Slowly building these small win-win situations up will build a farmer’s confidence in the changes needed and help to bring them onside.
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