New General Binding Rules on Silage & Slurry What’s changed?
New amendments to the rules around how we manage and store silage and slurry were introduced on 1st January 2022 with the aim of protecting the environment and helping to make better use of nutrients produced on farm.
The Controlled Activities Regulations (CAR) were updated to include the 2003 “SSAFO Regs”, formally known as the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations 2003, (as amended) putting the majority of regulations about slurry and silage handing and storage into one place.
Existing General Binding Rules (GBRs) were amended to provide clarity, and six new GBRs were added. In summary:
- GBR 29 relates to making and storing silage in bales or bulk bags
- GBRs 30 and 33 relate to the treatment of lightly contaminated silage and slurry through a constructed farm wetland.
- GBRs 31 and 32 relate to consolidation of SSAFO rules on the storage of silage and slurry.
- GBR 34 provides controls over the storage of liquid digestate, a by-product of the energy production process using anaerobic digestion.
The consolidation of SSAFO provisions into CAR also includes the removal of an exemption for silage and slurry stores constructed prior to September 1991. The broadcast spreading of slurry by splash plates will be phased out.
These new regulations and updates have been included in the handy Farming and Water Scotland ‘Know the Rules’ factsheets.
GBR 29 consolidates SSAFO rules on the making and storage of silage in bales or bulk bags.
| Ref | Points to note |
| GBR 29 (a) | Silage bales, or bulk bags, should not be stored, opened, or unwrapped within 10 metres of any surface water or opening into a surface water drain into which silage effluent could enter if it were to escape. |
| GBR 29 (b) ii | Bulk bags must be resealed when not in use to prevent escape of silage effluent, and incorporate a facility to safely remove effluent. |
Silage effluent consisting of mainly rainwater can be put to a constructed farm wetland (CFW) when the silo is open for use, drainage of the silage effluent is sent direct from the silo to the CFW from the base of the silo and no additional crop is added to the silo once open.
Silos include any structure used for making or storing silage. All structures (pre and post 1991) must be fit for purpose for use in 2022 to make silage – structurally sound impermeable floor with no cracks and have a suitable effluent collection system in place.
The current construction standards remain mostly unchanged.
| GBR ref | Points to note |
| GBR 31 (a)i | Silage stores constructed before September 1991 no longer have exempt status. This means they must comply with a basic set of construction standards [by 2026] |
| Silage stores constructed after September 1991 (or that were substantially reconstructed or enlarged after 1st Sept 1991) must comply with a basic set of construction standards [by 2024] | |
| GBR 31 (d) | Silage effluent collection systems using pumps and/or sumps must have an overflow alarm fitted, with a dedicated power supply. |
| GBR 31 (k) |
New silos after Jan 2022 must display the maximum loadings for the structure. |
| GBR 31 (o)i | SEPA must be notified 30 days before starting any work to build, substantially rebuild or enlarge a silo. |
| Amendment 5 | The storage of draff and crops for energy production now falls within these rules. |
The current construction standards remain mostly unchanged; irrespective of the dates below, structures will still need to be fit for purpose for use in 2022. A definition of lagoon liner materials has been included to cover a range of synthetic rubbers, plastics and reinforced geomembranes.
| GBR ref | Points to note |
| GBR 32 (a) to (d) | Storage capacity for slurry produced by housed livestock must be sufficient for 26 weeks for housed pigs and 22 weeks for housed cattle. This is a reduction on the current 6 months requirement and brings the CAR into line with NVZ requirements. Follow the formula used for NVZ’s – an online calculator will be made available. Account for rainfall entering the system, dirty yards, cleaning water/washings, imported slurries or digestate and any slurry imported/exported off farm during the housed period. |
| Slurry stores constructed before September 1991 no longer have exempt status. This means they must comply with a basic set of construction standards [by 2026] | |
| Slurry stores constructed after September 1991 (or that were substantially reconstructed or enlarged) must comply with a basic set of construction standards [by 2024] | |
| GBR 32 (o) | New, substantially reconstructed or enlarged slurry lagoons (after 1st January 2022) must be fitted with a suitable impermeable liner, which with proper maintenance slurry will not be able to permeate for a period of at least 20 years. |
| GBR 32 (q) | Slurry bags can be used, as long as they are in a lined bund of the same capacity as the slurry bag. There must be a mechanism to remove rainwater from within the bund. |
| GBR 32 (r) | SEPA must be notified 30 days before starting any work to build, substantially rebuild or enlarge a slurry storage system. |
| Restriction on size of slurry tankers removed. |
No major changes above current requirements.
The rules on the storage of liquid digestate are much in line with those for the storage of slurry. The construction standards for storage apply to all storage of liquid digestate whether on farm or other commercial sites.
| GBR ref | Points to note |
| GBR 34 (a) | Where liquid digestate is produced on farm, there must be sufficient storage capacity to accommodate the volume of liquid digestate produced during periods when application is not authorised under activity 18 of CAR, or would not comply with the requirements of the Action Programme for Nitrate Vulnerable Zones (Scotland) Regulations 2008. |
| GBR 34 (b) | Where liquid digestate is imported onto a farm, there must be sufficient storage capacity on the farm to store quantities imported during periods when application is not authorised under activity 18 of CAR or would not comply with the requirements of the Action Programme for Nitrate Vulnerable Zones (Scotland) Regulations 2008. |
| GBR 34 (n) | SEPA must be notified 30 days before starting any work to build, substantially rebuild or enlarge a storage system. |
| GBR 34 (n) o | Digestate can be stored in a slurry storage system which complies with requirements under GBR 32 |
A Risk Assessment for Manure and Slurry (RAMS) is now required for applications of organic fertilisers. A RAMS is an easy way to plan applications of organic materials whilst following good agricultural practice and reducing pollution risk. The risk assessment only needs to be carried when manures, slurries, and other organic materials (sewage sludge/digestate) are likely to be applied.
A RAMS map must be produced which identifies no-spread zones and spreading risks, providing a clear guide for contractors and farmworkers spreading manure, slurry or other organic fertilisers. Changes include notification on the RAMS map for any temporary field heaps.
The person carrying out the application of organic fertilisers must be provided with a copy of the risk assessment map for the area to which fertiliser is being applied,
Guidance on completing a RAMS map is available on the here and within the NVZ guidance.
What do you have to do and by when?
| Activity | Key Dates | ||||
| Jan 1st2022 | Jan 1st2023 | Jan 1st2024 | Jan 1st2026 | Jan 1st2027 | |
| Exempt status for pre 1991 silage and slurry stores lost |
X |
||||
| Silage and slurry stores built before 1991 (and not substantially enlarged or reconstructed since 1991) must be fully compliant by 2026 |
X |
||||
| Silage and slurry stores built after 1991 (or that were substantially reconstructed or enlarged on or after 1st Sept 1991) must make any upgrades to be structurally compliant by 2024 |
X |
||||
| Silage and slurry stores with planning permission but not yet constructed must be fully compliant by 2024 |
X |
||||
| SEPA must be notified 30 days before work starts on any new, reconstructed, or substantially enlarged silo/slurry/digestate storage facility. |
X |
||||
| Slurry stores constructed after 1st January 2022 must have capacity to store the total slurry likely to be produced in 26 weeks by housed pigs or 22 weeks by housed cattle |
X |
||||
| Slurry stores located outside an NVZ must have capacity to store the total slurry likely to be produced in 26 weeks by housed pigs or 22 weeks by housed cattle by 2026 |
X |
||||
| All liquid digestate stores constructed before 1st January, or where planning permission was granted piror to 1st Jan 2022, must meet requirements within the regulations |
X |
||||
| All slurry application must be applied using precision equipment2 |
X |
||||
| Liquid digestate must be applied using precision equipment |
X |
||||
| Slurry must not be applied using a raised splash plate or rain gun |
X |
||||
| Slurry must be applied using precision equipment if applied by a contractor |
X |
||||
| Slurry must be applied using precision equipment if applied on farms with more than 100 milking cows |
X |
||||
| Slurry must be applied using precision equipment if applied on farms with more than 100 milking cows, or 200 beef cattle livestock units3 |
X |
||||
| Slurry must be applied using precision equipment if applied pig units with more 800 fattening pigs or 800 sows |
X |
||||
2 Precision equipment = equipment capable of low emissions accurate application techniques including a dribble bar or band spreader, training hose, trailing shoe or direct injection. Low emission slurry spreading systems give more control over application and minimise runoff and emissions.
3 For the purpose of these provisions, a beef animal of 2 years and older is 1 unit; animal under 2 years old is 0.5 of a unit; dairy calculation based on number of individual milking cows.
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