https://defrafarming.blog.gov.uk/block-drains-in-grassland/
Block drains in grassland
The guidance on this page is for SFI pilot participants only. Please visit GOV.UK for the official Sustainable Farming Incentive scheme guidance.
Find out how land managers can create natural flows of water through grassland to improve flood resilience and enhance wetland habitats.
If you’re completing this action as part of the Sustainable Farming Incentive pilot, how you do it is up to you.
The advice on this page can help you get better environmental and business benefits, but you do not have to follow it to get paid.
About blocking in-field drains in grassland
You can block in-field drains or remove them to restore natural flows of water through grassland.
The natural passage of freshwater through rocks, soil and over land supports many habitats and species.
If you use artificial surface and sub-surface drainage, it will change the natural flow of water. This has led to the loss of many wet habitats and their species.
Benefits of blocking in-field drains
Blocking in-field drains to create small areas of wet ground on grassland will improve:
- natural water flows and drainage
- plant and invertebrate species diversity
- habitat for breeding wading birds like snipe
- flood resilience by slowing runoff into watercourses
- soil carbon storage and water quality
- the quality of natural wetland habitats
Wet grassland provides more cool refuges for species threatened by climate change. It will also help to reduce sediment-rich runoff into watercourses and sensitive habitats.
You can slow the flow of water as part of a natural flood management scheme.
Where to block in-field drains in grassland
You can block drains in grassland and other open grazed land where you do not use manufactured fertiliser.
Blocking drains can have significant benefits even within just a single field. For greater benefits you can work with neighbours to increase the area of natural wet grassland.
You’ll need to understand how the land is currently being drained. This will help you make sure the water stays in the right place. Look for:
- the source or sources of water onto the land
- where the drains currently direct the water
- how drains connect with the surrounding land
- any slopes or gullies
Block in-field drains on grasslands next to existing wetland flushes and marshes. Only block drains where the water is clean. This works well if they are close to the source of watercourses like small upland headwater catchments, where water quality will be good.
The types of drain to block or remove are small tile or pipe drains and small surface channels, both designed for the swift drainage of water.
Do not block:
- in-field drains in species-rich priority grassland.
- or damage historic drainage systems, like stone culverts or leats (open watercourses conducting water to a mill) that form part of industrial historic features.
How to block drains in grassland
You should carry out the work during the dry months of the year or when water is not flowing. If ground-nesting birds are present, wait until August or the end of the breeding season.
Sub-surface drains are best dug up and backfilled along their length. You should:
- Begin at the highest part of the grassland.
- Carefully remove the turf.
- Dig out the topsoil and any subsoil above the drain and keep them separate.
- Remove the drainpipes.
- When backfilling, replace the subsoil first and then the topsoil.
- Replace the turf.
Alternatively, smash tile or concrete drains along their length. Avoid leaving a flow path for water along the line of the broken drains.
You can use small earth dams to block shallow surface drains or depressions left by the removal of sub-surface drains. Avoid creating large areas of standing water.
Blocking drains will raise soil water levels and could affect neighbouring land.
You need to manage livestock numbers to avoid poaching. This can cause rushes to spread.
Exclude livestock during high rainfall periods and avoid using farm machinery on the wet areas.
How to know if you’re successful
You’ll see:
- a more natural flow of water through grasslands
- an increase in soil moisture
- higher water tables during the year
- less sediment runoff into adjacent habitats
- increasing numbers of wintering birds
