Silage Regulations

What you must do

Notify your environmental regulator in writing, before you use new or substantially reconstructed or enlarged silage stores.

In Northern Ireland the NIEA requires at least 28 days’ notice.

In Scotland SEPA requires at least 30 days’ notice.

Contact your environmental regulator

Silo design and construction

In Northern Ireland, all silage storage and effluent tanks built, or substantially enlarged or reconstructed after 1 December 2003 must comply with the following requirements.

In Scotland, from 1 January 2022 all silage storage and effluent tanks must comply with the following requirements, even those built before 1 September 1991, that were previously exempt.

The base of the silo must be constructed with channels to collect silage effluent from the silo, and with channels or pipes which must drain silage effluent to an effluent tank.

In Northern Ireland the capacity of the effluent tank must be at least—

• for a silo with a capacity of less than 1500m³, should have a quantity of not less than 3m³ for each 150 m³ of silo capacity, or
• for a silo with a capacity of 1500m³ or greater, should have a quantity of not less than 30 m³ plus 1 m³ for every 150 m³ of silo capacity in excess of 1,500 m³.

In Scotland the capacity of the effluent tank must be at least—

• for a silo with a capacity of less than 1500m³, 20 litres for every 1m³ of silo capacity, or
• for a silo with a capacity of 1500m³ or greater, 30,000 litres, plus 6.7 litres for every 1m³ of silo capacity over 1500m³.

Where pumps and sumps are used to collect the effluent, these must be fitted with an automatic overfill prevention device with a dedicated electrical supply and an alarm.

The base of the silo, the base and walls of its effluent tank and channels, and the walls of any pipes must be impermeable and must be resistant to attack by silage effluent.

Where the walls are made of earth, they must be lined with an impermeable membrane of 1000 gauge polyethylene or a material of at least equivalent impermeability and durability.

if the silo has retaining walls which are not made of earth, the stored silage level within that silo once compacted must be no greater than the height of the retaining wall.

For silage silos/pits built, reconstructed, or enlarged after 1 September 1991 you may also be required to comply with the following:

• comply with British Standard EN 1992-3:2006 and British Standard EN-1-1-2004 +A1:2014 (for concrete bases), or British Standard EN 13108-4:2016 (for hot-rolled asphalt bases),
• where the silo has retaining walls made other than of earth, extend beyond those walls,
• where any part of an effluent tank constructed, or substantially reconstructed or enlarged, on or after 1 September 1991 is installed below ground level, it must be designed and constructed in accordance with the Code of Practice on Buildings and Structures for Agriculture published by the British Standards Institution and numbered BS 5502-22:2003+A1:2013(5),
• a silo which has retaining walls which are not made of earth, must have retaining walls capable of withstanding the minimum wall loadings calculated in accordance with the Code of Practice on Buildings and Structures for Agriculture published by the British Standards Institution and numbered BS 5502-22:2003+A1:2013.

All new silage silos/pits (including a silo constructed from used materials), or substantially reconstructed or enlarged, on or after 1 January 2022, must have a life expectancy of at least 20 years, with proper maintenance.

Baled and field silage

You must not store or open any silage, in bales or bulk bags, within 10m from any water, including field drains and ditches into which silage effluent could enter if it were to escape.

The bulk bags must:

• have an impermeable membrane,
• be resealed when not in use, to prevent the escape of silage effluent,
• incorporate a facility to enable the removal of any excess effluent without spillage, and
• be situated on a firm level surface,

Silage bales must be wrapped and sealed into impermeable membranes or enclosed in impermeable bags.

Further information

The codes of good agricultural practice provide guidance on how to avoid polluting water with silage effluent.

In Northern Ireland, see section 2 of the DARD code of good agricultural practice for water, air and soil.

DAERA: Code of good agricultural practice for the prevention of pollution of water, air and soil

NIEA SSAFO Regulations in Northern Ireland

In Scotland, see GBR 29 and 31 in the CAR Practical Guide