Slurry, solid manure and silage effluent

This guidance is for farmers who spread:

  • livestock slurry
  • solid manure from agriculture
  • silage effluent.

What you must do

In Northern Ireland all farmers must comply with rules under the Nutrient Action Programme. 

DAERA: Nutrient Action Programme 2019-2022

In Scotland find out whether you are within a Nitrate Vulnerable Zone (NVZ). If you are within an NVZ you will need to follow certain rules, such as limiting the amount of organic and inorganic nitrogen fertiliser you use and keeping records.

Scotland: nitrate vulnerable zones (NVZs)

You must not let livestock slurry, silage effluent or manure enter rivers, streams or other watercourses. If you allow polluting effluent to enter surface waters or groundwater you may be committing a pollution offence.

Preventing water pollution

In Scotland you must not apply slurry or organic fertilisers:

  • within 10 metres of any drainage ditch or any surface water or wetland
  • within 50 metres of any well, spring or borehole that supplies water for human consumption, or any uncapped well or borehole
  • on land that is waterlogged or covered with snow
  • on land with an average soil depth less than 40cm that overlies gravel or fissured rock .

You must not apply livestock slurry on frozen land.

From 01 January 2022 updated Regulations come into force, relating to the management of silage and slurry.

The Water Environment (Controlled Activities) (Scotland) Amendment Regulations 2021

In summary, the updates relating to the management of silage and slurry are:

GBR 18 relates to the storage and application of fertiliser.

GBR 18 has been updated to include 2 new rules -

  • New rule (n) is introduced to require risk assessments to be carried out where organic fertilisers are to be applied to land, including the preparation of a map identifying areas of high risk where field heaps must not be located.
  • New rule (o) is introduced to GBR 18 to provide that precision equipment must be used to apply to slurry and liquid digestate, and for most cases, comes into force on 1 January 2023.

GBR 29 relates to the making and storage of silage in bulk bags.

The rules now state that bales or bulk bags must not be stored, opened or unwrapped within 10 metres of any surface water or opening into a surface water drain which silage effluent could enter if it were to escape.

GBR 30 relates to the treatment of silage effluent through a constructed farm wetland.

Continues to allow silage effluent to be drained to a constructed farm wetland, however the calendar restriction which previously applied has not been incorporated, and the drainage may take place when the silo has been opened.

GBR 31 relates to the making and storage of silage other than in bales or bulk bags.

The rule provides detailed requirements for silos. Different requirements apply depending on when the silo was constructed. Silos constructed prior to 1 September 1991 are no longer exempt.

  • Previously exempt silos have until 1 January 2026 to comply with the requirements.
  • Silos constructed or granted planning permission before 1 January 2022 (which were not previously exempt) have until 1 January 2024 to comply.

GBR 32 provides detailed requirements for slurry storage systems.

Different requirements apply depending on when the slurry storage system was constructed. Slurry storage systems constructed prior to 1 September 1991 are no longer exempt. New rules are included to allow slurry to be stored in suitable slurry bags. The rules relating to the required minimum capacity of the storage have been revised to be consistent with the requirements which apply in nitrate vulnerable zones under the Action Programme for Nitrate Vulnerable Zones (Scotland) Regulations 2008, based upon the quantity of slurry produced in 22 weeks for housed cattle or 26 weeks for housed pigs.

  • Previously exempt slurry storage systems have until 1 January 2026 to comply with the requirements.
  • Slurry storage systems constructed or granted planning permission before 1 January 2022 (which were not previously exempt) have until 1 January 2024 to comply. Where the activity takes place outside a nitrate vulnerable zone, the new requirements relating to the minimum capacity of the storage do not apply until 1 January 2026.

GBR 34 provides detailed requirements for the storage of liquid digestate.

Liquid digestate storage systems and slurry bags which were constructed or which were granted planning permission before 1 January 2022 have until 1 January 2024 to comply.

Good practice

You should:

  • spread manure, dirty water and slurry from livestock premises to land in line with good agricultural practice
  • match the amount of nutrients you apply to the needs of your crops (especially phosphorous and nitrogen) by drawing up a nutrient management plan
  • supervise the work of contractors spreading your slurry to ensure they are aware of the codes of good agricultural practice and the advice on high-risk and non-spreading areas
  • monitor the content of metals in pig and poultry manures and in the soil on fields which receive regular applications.

A manure management plan will help you decide when and where to spread your organic manures. It should take into account slope, watercourses, drainage, soil type, crop type and rainfall. The codes of good agricultural practice will help you develop a manure management plan.

In Northern Ireland, see section 3 of the DAERA code of good agricultural practice for water, air and soil.

The NIEA has produced a leaflet about the problems caused by ammonia emissions and what can be done to reduce them.

NIEA: Leaflet on ammonia

In Scotland, see section 4 of the Prevention of Environmental Pollution from Agricultural Activity (PEPFAA) Code and the 4 Point Plan.

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Further information

The codes of good agricultural practice also provide general advice on how to prevent nitrates and phosphorous leaching from your fields into the water environment.

In Northern Ireland:

In Scotland:

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