NVZ closed periods – key dates and guidance

12 April 2023

Environment and climate
A watercourse in a field of grass

The vast majority of farmers in NVZs (nitrate vulnerable zones) will already be familiar with when closed periods start and finish. For those who are new to the regulations, here is a brief overview as you plan for your next crop.

Closed periods are the times of year when farmers in NVZs are not permitted to spread organic manures with high readily available nitrogen or manufactured nitrogen fertilisers.

To check whether you are farming in an NVZ, visit the Environment Agency's NVZs (nitrate vulnerable zones) map and search for your location.

Organic manures

Farmers in NVZs must not spread high readily available nitrogen manures on or between the following dates.

On grassland

  • Shallow or sandy soils – 1 September to 31 December
  • All other soils – 15 October to 31 January

On tillage land

  • Sandy or shallow soils – 1 August to 31 December
  • All other soils – 1 October to 31 January

What are high readily available nitrogen manures?

High readily available nitrogen manures are those with more than 30% of their total nitrogen content immediately available to crops.

They include poultry manure (layer manure and litter) and liquid organic manures (such as sludge, cattle, and pig slurries and anaerobic digestate).

Manufactured nitrogen fertilisers

Farmers in NVZs must not spread manufactured nitrogen fertiliser on or between the following dates:

  • On grassland – from 15 September to 15 January
  • On tillage land – from 1 September to 15 January


There are exceptions to the closed periods for both manures and fertilisers.

Please check the relevant guidance at: GOV.UK | Using nitrogen fertilisers in nitrate vulnerable zones.

Appeals process

To find out about the NVZ appeals process - please see our guidance and member webinar below:

More information

For broader guidance on NVZ rules, please visit: GOV.UK | Nitrate vulnerable zones

Defra’s Farming Advice Service is another useful source of information on NVZ rules. You can contact the service on 03000 200 301.

Our NFU CallFirst service can also help direct you to an NFU adviser. Contact CallFirst on 0370 845 8458

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