Buffer strips are areas of land maintained in permanent vegetation that can be used to protect existing features such as hedgerows, trees, archaeology and water bodies. They are a popular way of reducing diffuse pollution but it is important to ensure they are used to maximum efficiency
What do I need to do to ensure good buffer strip creation?
- Aim to create a dense grass sward that is capable of slowing the passage of water from adjoining fields into the watercourse. This can be done through natural regeneration or sowing, providing vegetation cover capable of intercepting surface run-off all the year round.
- Remove any compaction from topsoil and any rills or gullies during seedbed preparation unless archaeological features are present. If you have an ELS agreement, archaeological features will be marked on your Farm Environment Record/Environmental Information Map.
- Avoid using heavy equipment during seeding, especially near the top of a stream bank as this could collapse the bank. Heavy equipment can also cause compaction of the soil under the buffer strip, which will reduce its ability to absorb water.
- Regular cutting (2-3 times) in the first 12-24 months may be needed to control annual weeds and encourage grasses to tiller (this is permitted under GAEC 12 if you are establishing a buffer strip).
How can I manage buffer strips most effectively?
- Density of grass is important to slow the flow of water. Silt will accumulate over time within the buffer strip, but if the grass is not smothered vegetation growth will eventually root into the silt and incorporate it into the soil.
- If non-organic, only apply herbicides to spot-treat or weed-wipe for the control of injurious weeds (i.e. creeping and spear thistles, curled and broadleaved docks or common ragwort) or invasive alien species (i.e. Himalayan balsam, rhododendron or Japanese knotweed).
- Maintaining a thick grass cover during winter and spring is particularly critical as this is when surface run-off and erosion from adjoining fields is most likely to occur.
What should I try to avoid?
- Compaction and poaching as this affects the capacity of the buffer to absorb water. Do this by avoiding cutting when soils are wet, by not using riparian buffers for regular vehicle access, turning, livestock movement/grazing or storage, and by limiting travelling across buffers to dry periods when the risk of compaction is reduced.
- Avoid excessive grazing pressure (e.g. rabbits / deer / invertebrate infestation).
- Don’t cut before August to avoid disturbing ground nesting birds.
- Avoid applying fertilisers or manures at any time.
Mitigating pollution using buffer strips
Scientists at Rothamsted Research North Wyke have looked at how installing buffer strips under the current Environmental Stewardship (Entry Level Scheme, ELS) can help mitigate pollution. Some findings from the recent ‘Multi-pollutant treatment of agricultural runoff by buffer zones, bioreactors, ditches and ponds workshop’ are that:
- A targeted rather than blanket approach to buffer strip implementation should be adopted and they should be considered as part of a suite of measures, both in field and edge of field, and not as a last resort. This, together with careful management, seems to work most effectively.
- Uncertainty and variability in the performance of buffer strips means they should be considered in terms of the wide range of benefits they can deliver, not just individual eco-system services.
- Simple measures such as establishment of plough furrows at the upslope edge of buffer strips can be effective for sediment trapping.
- Buffer strips require management and this must be varied depending on their primary function and environmental characteristics.
- Despite a wide range of reported efficiencies, overall they have a positive impact and should therefore be implemented more widely.
Click here for further information and to view the report.
Sources: Diffuse Agricultural Pollution Mitigation Methods workshop and workshop report and Natural England Technical Information Note TIN100; Protecting water from agricultural run-off; buffer strips