Plateau du Neubourg Results-Based Nitrogen PES — Paying Farmers Around the Tremblay-Omonville Catchment (France)

The Tremblay-Omonville catchment (about 6,200 ha, 5,900 ha of agricultural land, 125 farms) supplies drinking water to roughly 6,960 inhabitants and suffers from nitrates; parts of the wider territory exceed 40 mg/L. A leaching model indicates that if the winter incoming nitrogen balance stays below 60 units N/ha/yr, catchment nitrate would fall below 37.5 mg/L, with about 30 years of latency between practice change and aquifer response.
Since 2019 the water syndicate SERPN has run a payment-for-environmental-services scheme financed 100% by Agence de l'eau Seine-Normandie (€2 million over five years). Payment is for results: about 50 farmers receive €80–125/ha if residual nitrogen measured parcel by parcel at the start of winter is under the threshold (e.g. 50 u/ha after rapeseed paying €80/ha; 45 u/ha after a spring crop or 60 u/ha between two cereals paying €125/ha). A collective bonus of €15/ha (above 30% of surface enrolled) or €40/ha (above 80%) rewards group uptake. The rate was calculated by a water-agency economist.
Reported uptake in 2019 was 64% of surfaces (188 parcels) with 37% of parcels exceeding the threshold; the target was 80% of surfaces by 2024. An observatory sampling fields since 2013 provides the monitoring base. No measured improvement in catchment nitrate has been reported, so the evidence concerns practice indicators and modelling rather than outcomes in the water.

Read the full analysis: https://cpes-interreg.eu/en/cpes-project/our-pilot-sites/tremblay-omonville-catchment