poole harbour

Farmers in Dorset’s Poole Harbour catchment are aiming to become some of the most nitrogen efficient in the UK.

Poole Harbour is designated as a Special Protection Area (SPA), Site of Special Scientific Interest (SSSI) and Ramsar site. But an increase in nutrients entering the harbour waters over the last 50 years has led to a deterioration in water quality and affected wildlife.

The amount of nitrogen entering the harbour has more than doubled, from around 1,000t/year in the 1960s to around 2,300t/year now. As a result, the harbour’s mudflats have become covered in green algae, which has smothered sea grass and saltmarsh, impacting on wetland birds and other ecosystems and wildlife.

Now local farmers in the Poole Harbour catchment are aiming to become some of the most nitrogen efficient in the UK. They are taking on the responsibility of reducing their nitrogen losses from their soils to a point that will not harm the environment and are developing a nutrient management scheme to meet their ambition.

This new approach follows the publication of the Environment Agency and Natural England’s Poole Harbour Consent Order Technical Recommendations (PHCOTR), which sets new interim nitrogen and phosphorus targets for the catchment. PHCOTR states that nitrogen loads which reach the harbour should be reduced from around 2,300 to 1,500 t/year, and ortho-phosphate (OP) loads should be reduced from around 51 to 22 t/year.

New emission limits

Wessex Water, local authorities, local industries and the general public all play a role in reducing nutrients entering the harbour. However, it is farming that contributes the largest source of nitrogen to the catchment, and a significant amount of phosphorus.

The government has set new emission limits and measures that farmers should follow to ensure their activities do not cause harm to the water environment. Farmers now need to start to plan and implement the measures to achieve these objectives, and from 2023 farmers need to ensure their nutrient losses across their farm holding (or group of farm holdings) do not exceed 18.1 kg/ha/year of nitrogen.

Or where the farmer joins an Environment Agency-approved scheme, they need to meet alternative glide path targets which will achieve the emission target by 2030. In such a scheme, all farmers are incentivised to maximise efficiency (and no farmer can apply above crop need), but farmers that have reduced their losses below the glide path can trade nitrogen credits to farmers looking to offset some of their nutrient losses. These timescales align with water company improvements delivered through their capital investment programme.

New tools are being provided, including the Nitrate Leaching tool (NLT) and Agricultural Compliance Tool (ACT), which farmers can use to calculate the amount of nutrients they are losing to the environment and to ensure they are compliant with existing regulations. Farmers will need to use these tools (or other agreed tools) each year to ensure their nutrient plan and farm practices meet these new emission limits and requirements.

Starting this year, farmers must report to the government, or the independent body overseeing any approved scheme, on their compliance and nutrient loss. Those farmers not returning information are likely to be prioritised for inspection by newly-appointed Agricultural Officers.