NVZ Compliance Calculator
Check if your farm is in a Nitrate Vulnerable Zone and calculate the organic nitrogen loading from your livestock against the 170 kg N/ha/year limit (or 250 kg/ha with grassland derogation).
1. Your farm location
Used to check automatically if your farm is in an NVZ.
Closed spreading periods (England baseline)
- Cattle, sheep, goats, deer, horses — slurry/manure: 1 October – 1 March
- Pigs and poultry — slurry/manure: 1 October – 1 April
Wales, Scotland and Northern Ireland set their own closed periods — check your jurisdiction’s guidance.
About this calculator
Livestock nitrogen coefficients are taken verbatim from DEFRA NVZ guidance standard values tables (PB 14050). NVZ designation polygons for England are from DEFRA NVZ 2021 Designations. Regulatory framework: Nitrate Pollution Prevention Regulations 2018 (England). Contains public sector information licensed under the Open Government Licence v3.0.
What this tool does: detects whether your location is in an NVZ and calculates whole-farm organic nitrogen loading from livestock.
What this tool does not do: field-by-field nutrient planning, manufactured fertiliser N calculations, crop N max, or spreading records. For record-keeping required by DEFRA (5 years), use a dedicated farm management system.
Wales and Northern Ireland are entirely designated as NVZ under their own devolved regulations (Water Resources (Control of Agricultural Pollution) (Wales) Regulations 2021 and the DAERA Nitrates Action Programme). Closed periods and storage rules differ from England — check your jurisdiction.
For decisions about your farm, consult an agronomist or the Rural Payments Agency.