Storing organic manures in nitrate vulnerable zones

How to provide enough storage and keep storage records of organic manures in a nitrate vulnerable zone (NVZ).

Organic manures come from animals, plants or humans. They include:

  • slurry
  • poultry manures
  • solid manures (such as farmyard manure, sludge cake or compost)
  • sewage sludge (also called biosolids)
  • other liquid manures (such as abattoir waste or anaerobic digestate)

Slurry is a liquid organic manure that is produced by livestock (other than poultry) while in a yard or building. It includes animal bedding and water that drains from areas where animals are kept.

You must follow this guidance if a part or all of the farm buildings from which your slurry comes is within an NVZ. You must also follow the guidance on the rules for using nitrogen fertilisers in NVZs and storing silage, slurry and agricultural fuel oil.

Separating slurry into solid and liquid parts

If you separate slurry into solid and liquid parts you must do so either using a purpose-built machine or on a waterproof surface where you can collect the liquid that drains from it.

If the solid that remains can be stacked in a heap without leaking liquid, it can be treated as farmyard manure. If not, it’s still slurry. If there is leakage from a stack, you must collect this and treat it as slurry.

Storing slurry and poultry manure

You must be able to store all the slurry you produce and all poultry manure produced in a yard or building, during the storage period, unless you reduce the volume by:

  • sending it off your farm
  • spreading some of it on fields with a low risk of runoff

The storage period runs from:

  • 1 October to 1 April inclusive (6 months) for pigs and poultry
  • 1 October to 1 March inclusive (5 months) for cattle, sheep, goats, deer and horses

In addition to storing the slurry you produce, you must provide storage for any slurry, rainfall, washings or other liquid that enters the store during the storage period.

For rainfall, average figures for each month of the storage period can be used for the storage capacity calculation. Use the Defra PLANET and MANNER NPK nutrient management tools to get rainfall information for your postcode.

You may need to use a longer average rainfall period for your calculation to make sure you comply with the closed period and non-spreading conditions. For example, 6 and 7 months respectively to cover wetter than average years and spatial rainfall differences within a postcode area (for example height above sea level).

You may need a greater storage volume if in some years you can’t empty the store before the start of the closed period.

You should allow for:

  • all rainfall expected to enter the store during the storage period (rain falling directly into the store and washings from elsewhere, including contaminated yards)
  • any water or other liquids that enter the store during the storage period

To find out how much manure your animals will produce, you can use standard values tables (XLSM, 128KB) or farm software like the MANNER NPK tool.

Using low risk land

You can spread slurry or poultry manure on fields that have a low risk of runoff, to reduce the amount of storage capacity you need to provide.

If you do this, you must still comply with the closed period for spreading slurry.

You’ll also need to take account of the limits on spreading slurry or poultry manure from the end of the closed period until the end of February.

Land with a low risk of runoff:

  • has an average slope of less than 3 degrees
  • doesn’t have land drains (other than a sealed pipe)
  • is at least 50 metres from a watercourse or conduit leading to a watercourse (like a ditch or working land drain)

You must provide storage facilities for an additional 1 week’s manure as a contingency measure in case you can’t spread on fields with a low risk of runoff on some days.

Storing solid manures

You must store poultry manure, other types of solid organic manure or animal bedding that contains organic manure in one of the following ways:

  • in a container
  • on a waterproof base, where you can collect and store runoff
  • in a roofed building
  • in a temporary field heap

Locating and constructing temporary field heaps

You must:

  • make sure your field heap is at least 10 metres from any surface water (such as a river, pond or ditch) or land drain, or 30 metres if the land slopes at 12 degrees or more
  • make sure the location of the field heap isn’t liable to being waterlogged or flooded
  • locate field heaps at least 50 metres from a spring well or borehole
  • move the field heap at least every 12 months
  • leave a 2 year gap before returning to the same site
  • keep a record of the sites used for field heaps and the dates of use

You must show all the low risk areas suitable for temporary field heaps on your risk map if you plan to use them.

Temporary field heaps must:

  • be made from manure solid enough to be stacked in a freestanding heap
  • not give rise to free drainage from within the stacked material
  • be covered with a waterproof material if they contain poultry manure without bedding or litter
  • occupy as small a surface area as is needed to support the weight of the heap without it collapsing

Constructing or enlarging your storage facilities

If you’re constructing new storage for slurry, reconstructing part of a storage facility or enlarging your current storage facilities, you must follow the rules on storing silage, slurry and agricultural fuel oil.

Keeping storage records

You must record:

  • the capacity of the storage facilities on your farm (and update any changes to this within 1 week of the change)
  • your calculation of the volume of manure that will be produced by the livestock you’ll keep in a building or on hard standing during the storage period
  • your calculation showing the amount of storage you need
  • any changes in volume and storage capacity due to introducing livestock onto your farm for the first time (within 1 month of the change)
  • your calculations to show how you’ve reduced your volume by sending slurry off your farm or spreading it on low-risk areas (if relevant)

By 30 April each year make a record of:

  • the numbers and type (‘category’ in the standard values tables (XLSM, 128KB) ) of livestock you kept in buildings or on hard standing during the previous storage period
  • the dates for the start and end of use and locations of any field sites you use for storing solid manure

You don’t need to record the start and end dates for your use of field sites separately if you record them on your risk map.

You must keep these records for 5 years.

Where to get help

Contact the Farming Advice Service for more information on using and storing nitrogen fertilisers and manures.

Telephone: 03000 200 301 (Monday to Friday, 8am to 6pm)


Published 10 August 2015
Last updated 25 January 2017 + show all updates
  1. Changed contact phone number
  2. Changed text on separating slurry to make it clear that it's something farmers can do but might not always do.
  3. First published.