Guidance

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).

• From: Department for Environment, Food & Rural Affairs and Environment Agency
• Published: 10 August 2015
• Last updated: 12 October 2023 — See all updates

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 liquid and more solid manure

If you separate slurry you need to store and spread the separated liquid and more solid organic manure correctly. Follow the guidance on using a mechanical slurry separator to manage your 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.

When you calculate the slurry storage capacity you’ll need, you have to allow for wetter than average rainfall years (1 in 5 year). You can use the Agriculture and Horticulture Development Board (AHDB) slurry wizard. This converts your average rainfall into wetter than average for you.

Dairy farmers can also use the slurry wizard to calculate the amount of:

• slurry their cows will produce
• rain falling directly into the store and from contaminated yards
• washings or other liquids that enter the store during the storage period

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

You can also use the AHDB slurry wizard to calculate and compare your existing capacity with your needed capacity. This will indicate if you’ll have to:

• reduce the volume of slurry
• provide additional capacity

For new or substantially changed slurry storage you also need to comply with the slurry storage rules.

To find out how much manure your animals, including other cattle and pigs, will produce, you can also use the standard values tables (128 KB).

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
• does not 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 cannot 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 is not 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 (128 KB)) 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 do not 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)

Email: [email protected]

Published 10 August 2015
Last updated 12 October 2023 + show all updates

1. 12 October 2023

   Added link to guidance for using a mechanical slurry separator to manage your slurry.

2. 28 October 2019

   Amended text under heading 'Storing slurry and poultry manure'. Removed references to PLANET and MANNER NPK. Instead linked to AHDB slurry wizard which allows for wetter than average rainfall.

3. 25 January 2017

   Changed contact phone number

4. 15 September 2015

   Changed text on separating slurry to make it clear that it's something farmers can do but might not always do.

5. 10 August 2015

   First published.