Introduction to Nitrate Vulnerable Zones

A Nitrate Vulnerable Zone (NVZ) is an area at risk of pollution from nitrates due to agricultural activity. The areas are designated by DEFRA and include approximately 55% of land in England. If your holding is in such a zone then the use of nitrogen fertilisers and storage of organic manure must comply with the NVZ regulations.

In order to receive payments from the Basic Payment Scheme (BPS) and Rural Development Programs (RDPE), Countryside Stewardship and Countryside Productivity, all NVZ and other cross compliance rules must be adhered to. This is checked in the form of cross compliance inspections by the RPA and if an inspector decides the regulations are not being complied with then payments may be reduced.

How to find out if your holding is in an NVZ

The Environment Agency (EA) provides an online map which highlights areas in an NVZ and can be searched by postcode or name of holding. When clicking on the area of your holding it will show the reason for designation e.g. surface water issues and a link stating what you need to do to comply.

DEFRA reviews the NVZ designations every four years as the concentration of nitrates in an area can fluctuate over time.  When the area is redrawn DEFRA will notify all farmers and landowners within the area by letter. After an initial designation you have 28 days to appeal your holding’s inclusion before the area is finalised. The current area is established for 2017-2020.

Use of nitrogen fertilisers

This involves the spreading of any fertiliser containing nitrogen, including both manufactured and organic, on agricultural land within an NVZ. To control this process there are limits on the average amount that you can apply to your fields, the ‘N-max limit’, i.e. the amount of nitrogen (N) which can be applied in tonnes per hectare per year. This varies depending on the crop and the time of year it is sown, as well as the soil nitrogen content and type of fertiliser.

Planning your nitrogen use and keeping records

Applications of nitrogen to each type of crop (including grassland) must be planned, recorded and kept for five years as part of your farm records, and made available for inspection upon request. These records will include a Fertilisation Plan, Field Records, an NVZ Risk Map and your Livestock Records as part of an overarching NVZ Plan. Your NVZ plan will show that you have taken into account the amount of nitrogen already in the soil and available to the crop throughout the growing season, the amount that should be applied to a specific crop for optimum yield, the amount present in any planned applications of manure applied throughout the growing season, and/or the amount of manufactured nitrogen to be used. The risk of run-off when spreading or stored (i.e. muck heaps) must also be assessed.

Fertilisation Plan and Field Records

The first stage occurs before fertiliser is applied and involves creating the Fertilisation Plan and updating your Field Records as follows:

  1. Make a record of the names and areas of the fields;
  2. Record the type of crop to be grown and the expected yield, if it’s grass then whether it will be cut or grazed, the month you plant the crop, and the crop nitrogen requirement;
  3. Record the soil type;
  4. Note the previous crop grown (if grass then if it was cut or grazed);
  5. Record the soil nitrogen supply and note the method used to work this out.

Your previous yields will allow you to estimate your expected crop yield.

If using organic manure you will then need to record:

  1. The area on which you will be spreading organic manure
  2. The amount and type of manure to be spread
  3. The month it will be spread
  4. The total nitrogen content of the manure
  5. The amount of nitrogen that will be available for crop uptake in the growing season


  1. The amount of nitrogen from manufactured fertiliser required, based on the amount nitrogen available from applications of organic manure (if any).
  2. The month in which the manufactured fertiliser will be applied

The total size of your holding must be recorded and updated within a month of any changes. This includes any area not covered by greenhouses and excludes surface water, buildings, roads and woodland not used for grazing.

If applying manure to permanent grassland the calculations should be based on a farming year starting on 1st January then preparing a plan for any fertiliser/manure used after that date.

Calculating the amount of nitrogen in the soil

To calculate the nitrogen in the soil you can use the SNS (soil nitrogen supply) method found in the AHDB Nutrient Management Guide RB209. This allows you to work out the soils capacity to supply nitrogen to a crop and therefore the amount of additional nitrogen required from fertiliser. The field assessment method described in the RB 209 follows these steps:

  1. Identify the soil category for the field
  2. Identify the previous crop
  3. Select the rainfall range for the field
  4. Identify the provisional SNS Index using the appropriate table
  5. Make any necessary adjustments to the SNS Index

The amount of nitrogen to apply to a specific crop

The ‘N-max limit’ refers to the amount of nitrogen which can be applied across your fields. This amount, which is recorded as tonnes per hectare per year, varies depending on the crop and the time of year sown. You may apply more if the expected yield is higher than the ‘standard crop yield’, e.g. wheat and barley crops can receive an additional 20kg N/ha for every tonne that the expected yield exceeds the standard yield. The table below shows the maximum amount of nitrogen that can be applied to a specific crop.

The N-max limit for specific crops:

Crop N-max limit (kg N/ha) Standard crop yield (tonnes per hectare)
Autumn or early winter-sown wheat 220 8
Spring-sown wheat 180 7
Winter barley 180 6.5
Spring barley 150 5.5
Winter oilseed rape 250 3.5
Sugar beet 120
Potatoes 270
Forage maize 150
Field beans 0
Peas 0
Grass 300
Asparagus, carrots, radishes, swedes, individually or in any combination 180
Celery, courgettes, dwarf beans, lettuce, onions, parsnips, runner beans, sweetcorn, turnips individually or in any combination 280
Beetroot, brussels sprouts, cabbage, calabrese, cauliflower, leeks individually or in any combination 370
Source: GOV.UK


Organic fertiliser

Organic fertiliser includes compost and manure both brought onto the holding and produced by livestock, the nitrogen levels within must be calculated by the farmer. Livestock manure, whether it is deposited directly by livestock or through spreading, is limited to 170kg N/ha over the course of the year. This is called the ‘loading limit’ and is applied across the whole holding as an average. The ‘field limit’ for organic manure applied in any one field is 250kg N/ha over the year. This ‘field limit’ does not include the manure deposited by grazing animals. If the only organic manure used is certified green/food compost you can apply 500kg of nitrogen every two years as mulch, worked into the ground, or 1,000kg every 4 years.

Derogation applications

Farmers with at least 80% grassland can apply for derogation by contacting the EA, usually between 1st October and 31st December and having effect for the following year.  If you had a derogation for 2019 then you must submit information to the EA for that year in the form of a ‘fertilisation account’ by 30th April 2020. A derogation effectively increases the ‘loading limit’ for manure from 170 N/Ha per year to 250 N/Ha/ per year. You need to re-apply each year.

Records of livestock/manure

Between 1st January and the 30th April each year you must create records detailing the following for the entirety of the previous calendar year:

  • The number of livestock on your holding
  • The type of animal and its category (usually age/sex based) and number of days it spent on the holding
  • A calculation of the amount of nitrogen produced by all your animals
  • The start and end dates of any field heaps used to store solid manure, with their locations on the risk map

To ensure these figures are accurate ensure your movement books for livestock are up to date and kept with the other records in your NVZ Plan. They will be providing the data for your manure calculations in conjunction with the area in your field records and will be checked during an inspection. If bringing manure onto or off your holding you must record the amount and date as well as its nitrogen content. Also record the name and address of the recipient or supplier and a contingency plan (such as storage) if the manure isn’t accepted by a recipient.

Working out the nitrogen content in organic manure

To calculate the amount of nitrogen created by your livestock/brought onto the holding you must use the values found in the ‘blank field records and standard values table’ found online in the ‘NVZ guidance blank completion data tables’. This explains how to calculate the average amount of nitrogen produced in the manure of various types of livestock over the course of a year.

If bringing organic manure onto the farm, use the technical analyses supplied by the fertiliser supplier to work out the amount of nitrogen contained within. You can also use the ‘fertiliser manual’ within the RB209 to work out the value.

You need to plan ahead so that you do not go over the total ‘loading limit’ of the holding, no organic manure should be spread to a crop with an N-max limit before the nitrogen content is worked out.

Risk Map

Assessing the risk of run-off

As part of the farming rules for water introduced on 2nd April 2018, and enforced by the EA, it is an offence to let fertiliser enter surface water. The risk of run-off from your fields must be considered, if there is risk then you must not spread.

Once the Fertilisation Plan and field records are complete then, if spreading organic manure, a risk map must be created. This map can be hand drawn or printed out and must be updated within 3 months of any change. It must show areas at risk including the following:

  • The location and area of each field
  • Land with a slope greater than 12 degrees
  • Areas with sandy or shallow soils
  • The location of land drains and field heaps
  • All surface water and the land within 10m of it
  • All springs wells and boreholes both on your holding and within 50m of your holding; shading the land within 50m of each one.
  • Any low run-off risk land

All fertilisers must be spread as accurately as possible whilst avoiding these areas. They may only be spread on areas of land that have a crop growing on it.

Restrictions on spreading

Neither manufactured nor organic manure may be spread if a field is waterlogged, flooded, covered in snow or frozen for more than 12 hours out of the previous 24 hours. Neither type may be spread during its ‘closed period’ outlined below.  Areas where you must not spread certain nitrogen fertilisers include:

  • Manufactured fertiliser within 2m of surface water.
  • Manufactured fertilisers within a 2m zone from the centre of a hedge (if you need to meet cross compliance requirements).
  • Manure within 50m of a spring, well or borehole or 10m of surface water.


If using precision spreading equipment such as band spreaders, shallow injectors or dribble-bar applicators then slurry, sewage and anaerobic digestate can spread to within 6m of surface water.

Straw-based solid manure may be spread within 10m of surface water on sites of Special Scientific Interest or those under an agri-environment scheme if you are managing the land for breeding wader birds or the land is designated  as ‘species rich semi-natural grassland’. The spreading can only occur between 1st June and 31st October and not directly into surface water and not more than 12.5 tonnes per ha each year.

Closed periods

Manufactured nitrogen fertiliser: Cannot spread manufactured fertiliser – Grassland 15th Sep – 15th Jan; Tillage land 1st Sep – 15th Jan.

Exceptions to the closed periods for manufactured nitrogen fertilisers

Manufactured fertiliser can be spread during the closed period if certain crops are grown and the time frame and limits are abided by. If your crop isn’t listed in the table below you should obtain written advice from a professional adviser before spreading.

Crop Maximum amount of nitrogen you can spread within the closed period on each hectare
Winter oilseed rape 30kg (you must not spread nitrogen after 31 October)
Asparagus 50kg
Brassica 100kg (no more than 50kg can be applied every 4 weeks, up to the date on which you harvest the crop)
Grass 80kg (you can apply a maximum of 40kg at any one time, and you must not spread nitrogen after 31 October)
Over-wintered salad onions 40kg
Parsley 40kg
Bulb onions 40kg
Source GOV.UK


You must not spread high readily available nitrogen manures on the following dates depending on the type of soil and whether the land is tillage land or grassland.High readily available fertilisers include poultry manure and liquid organic manure such as sludge, cattle and pig slurry, poultry manure and anaerobic digestate. They have more than 30% of their nitrogen content immediately available to crops and have ‘closed periods’ when they may not be spread.         

Closed period for manures with high readily available nitrogen

Sandy or shallow soil: Grassland – 1st Sep – 31st Dec; Tillage land 1st Aug – 31st Dec.

All other soil: Grassland 15th Oct – 31st Jan; Tillage land 1st Oct – 31st Jan

If you sow a crop on sandy or shallow tillage land on or before 15th September, you can apply manures with high readily available nitrogen between 1st August and 15th September.

Organic farm exceptions

Organic farmers, or those formally converting to organic status, are restricted to 150kg of N/ha but can spread high readily available nitrogen manure, depending on the crop, in certain periods.

  • Asparagus, overwintered salad onions, parsley and bulb onions – the start of the closed period to the end of February.
  • Brassica – from the start of the closed period to the end of February, no more than 50 kg of N/ha every 4 weeks.
  • Winter oilseed rape – from the start of the closed period to the end of October.
  • Grass – from the start of the closed period to the end of October, no more than 40kg at any one time.

Restrictions outside the closed period

A single application of slurry must be no more than 30m3/ha or 8 tonnes/ha for poultry manure from the end of the closed period to the end of February with at least 3 weeks between each application.


Slurry must be spread with precision equipment or equipment with a low trajectory (below 4m from the ground) or thirdly equipment which spreads slurry at a maximum rate of 1mm per hour when operating continuously.

Organic manures spread on bare soil

If spreading on bare soil or stubble (except when sown with seed) then poultry manure, slurry, liquid-digestate and sludge must be worked into the ground as soon as possible and at least within 24 hours. Any other organic manure must also be worked into the soil within 24 hours if the land is sloping and within 50m of surface water. If slurry or liquid-digestate was applied using an injector, shoe band spreader, trailing hose or dribble bar applicator then it does not need to be worked in.


If you land is enclosed by a greenhouse/glasshouse/polytunnel for the entirety of the calendar year then there are no limits on fertiliser usage and records of use and yield of crops do not need to be kept. If the land is exposed to the open air at any point in a year, then the restrictions apply for the whole of that year.

Storage of organic manure


All slurry and poultry manure must be stored, unless it is sent off the farm or spread on fields of low risk land. The storage period starts on 1st October and runs until 1st March for cattle, sheep, goats, deer and horses and 1st April for pigs and poultry. Low risk land has a slope of less than 3 degrees, no land drains (unless sealed) and is 50m or more from a watercourse.

Solid Manure

Solid organic manure needs to have a consistency allowing it to be stacked in a free-standing heap whilst occupying as small a surface area as possible. It must not drain from within the stack and should be covered with a waterproof material if composed of poultry manure without bedding or litter. It can be stored in a container, on a waterproof base, in a roofed building or in a temporary field heap. Temporary muck heaps must be 10m or more from any surface water or land drains or 30m if the land slopes at 12 degrees or more. They must be 50m or more from a spring, well or borehole. The field must not be at risk of flooding/becoming waterlogged. Their location should be moved every 12 months or more with a 2 year gap before the same site is used. The site should be recorded on the risk map as described above.

Storage records

You should record the capacity of your storage facilities, the amount of storage you will need based on your livestock, when this changes based on bringing new livestock onto the holding and the reductions when you spread or send off farm. Any location of heaps should be recorded on the Risk Map as described above. All records should be kept for 5 years.

Managing livestock

To prevent livestock compacting soil (poaching) within 5m of inland freshwater or coastal water you must not place feeders within 10m of these water sources or 50m of a spring, well or borehole. Fences should be erected to keep livestock from causing bankside erosion whilst they should only be wintered on well-drained level fields.

Additional precautions

In addition to complying with the NVZ rules, you must take reasonable precautions to reduce water pollution when: cleaning ditches, installing drainage, irrigating crops, spraying pesticides/herbicides/fungicides and creating farm tracks/gateways. You can do this through actions like planting crops in dry conditions, breaking up compacted soil, creating buffer strips along field edges and planting beds across the base of sloping land.


Complying with NVZ regulations forms part of your cross-compliance and is a statutory management requirement (SMR). It is required to receive funding from BPS, Countryside Stewardship and Environmental Stewardship. The RPA will conduct random inspections and if non-compliance is found than there can be a reduction in funding regardless of whether the infringement is due to a mistake or otherwise. This can range from a 1% reduction in BPS up to 100%, based on the number and severity of breaches.

The main area of transgression tends to be sheep and cattle registration, specifically the movement records being incorrectly recorded or not recorded at all and sheep being incorrectly tagged. It is vital that these records are kept up to date and located with the farm records discussed above to avoid penalties.

You may not receive advance warning of an inspection and if you do it will probably be less than 48 hours. An inspector will tell you what you need to provide them with and any further help required. Once an inspection is complete the inspector will explain what they have found identifying any issue and assessing the seriousness of it against a set of ‘verifiable standards’. The RPA will decide on the penalty sending you information within 3 months in writing on the breach and how it will affect your claims. Refusing to allow an inspection or not co-operating could result in losing all your payment.