Changing arable land to grassland rich in wild plants can be a long process, but benefits for birds can be achieved more quickly.
Arable land can be reverted to grassland to increase the variety of habitat in predominantly arable areas.
It may help to buffer or link up areas of important grassland, to protect and extend existing habitats, to strengthen farm landscapes or to protect underlying archaeological features.
Pockets of arable cultivation within pastoral areas are also important, so conversion to grassland may not always be appropriate.
- Clear and appropriate objectives are essential.
- Seek advice to identify the most appropriate sites.
- Agri-environment schemes can fund reversion to meet specific objectives.
Benefits to wildlife
Arable reversion helps create a mixed farmed landscape for wildlife.
A mixture of habitat types benefits birds such as lapwings. They nest on arable land but their chicks forage for food on grassland.
The resulting grassland can provide nesting habitat for ground-nesting birds
Arable reversion grassland can provide valuable nesting habitat for birds such as lapwings, curlews, yellow wagtails and skylarks. Snipe and redshanks may nest on grassland with damp flushes. Specific management is essential to benefit any particular bird species.
Grassland can be a valuable food source for birds
Arable reversion grassland does not have to be botanically rich to be good for birds. Its structure is as important as species composition. Soil invertebrates, such as earthworms and insect larvae, benefit from the lack of cultivation and provide food for birds throughout the year.
Grasslands which contain broad-leaved plants, such as dandelion and sorrel, are particularly good for seed eating birds, such as linnets. An uncut margin or field corner may act as a wildlife refuge where birds can find seeds and invertebrates during the winter.
How to choose your site
- Ideal fields for reversion will be of low productivity and those which have been in arable production for less than 10 years. Such fields may still have desirable grassland species in the seed bank.
- Soil testing to assess soil pH and determine fertility and nutrient levels is important. Soil pH can be important in determining the type of plant species which will re-establish on a particular site and as an indicator of the possible weed burden.
- Fields with a low burden of injurious weeds, such as thistles, docks and ragwort, may help to avoid long-term management problems. High populations of annual grasses such as black grass and sterile brome are a threat to establishment.
- If you are aiming to produce a wet grassland community, control of an incoming source of water is essential.
- If the site is next to existing diverse grassland or target farmland birds, natural regeneration may be the simplest form of management.
- Some areas of the country have rare arable plants. These should be considered when reverting arable land to grassland and can be maintained by the use of cultivated margins.
Site preparation and sowing
Things to consider
- If weeds are a potential problem these should be tackled prior to sowing.
- The best time to sow is usually August, as this allows establishment before winter. In milder areas, sowing can be delayed until mid-September.
- Spring sowing can be successful but there is a greater risk of drought killing young seedlings.
- Cultivation should avoid the main nesting period where possible. Early nesters, such as lapwings, will be nesting from the end of March until the end of May.
It is possible to establish a wide range of grass and flower species, although grasses generally establish more successfully. Wild flowers such as yarrow, common sorrel and oxeye daisy establish fairly easily, whereas others, such as field scabious and harebells, are difficult to establish.
It is preferable to sow a limited range of native wild flowers using local provenance seed, rather than a wide range of species using foreign cultivars.
Arable reversion grassland does not have to be species-rich to benefit birds. More important for birds is how the site is managed by grazing and cutting.
Agricultural mixtures provide suitable grazing for over-wintering wildfowl. Grass varieties used in many agricultural seed mixtures usually only thrive with regular applications of fertilisers and this is generally not permitted in agri-environment schemes.
Tussocky grasses, such as cocksfoot, help produce a varied sward structure, valuable for ground-nesting birds, but may limit the variety of wild flowers.
Managing arable reversion
Grazing management is particularly important where the target species are breeding wading birds, such as lapwings and curlews.
In the establishment year, grazing is the preferred management method. Grazing can suppress weeds and prevent a few kinds of grasses dominating the sward. It improves grassland structure by creating gaps in the sward for seed germination.
The type of grazing animal is important. Cattle create a diverse sward with a mosaic of vegetation heights.
In subsequent years, grazing following a grass cut maximises benefits for wildlife. The sward height at the end of autumn aftermath grazing should be less than 10cm to help spring nesting waders. For lapwings, a sward height of 35cm is preferable.
Increasing the area available for grazing may enable farmers to manage existing grassland less intensively by reducing stocking rates. For example, most farmers entering an arable reversion option are eligible to apply for sheep and/or suckler cow quota from the National Reserve. The extra area of grazing provided by the reverted site may also enable farmers to stay within the stocking limits required to qualify for the Extensification Payment or Super-Extensification Payment under the Beef Special Premium Scheme or Suckler Cow Premium Scheme.
Taking a grass crop helps to remove some soil nutrients such as nitrogen and potassium, but care should be taken where ground-nesting birds such as curlews, corn buntings and skylarks are present.
Where possible cut grass late to allow seeding of late flowering species and to avoid the nesting period of birds. Sustained early cutting will reduce the variety of flowers and be harmful to ground nesting birds. Uncut corners and margins create structural diversity.
Adopting wildlife friendly mowing practices, such as cutting from the centre outwards, or mowing from one side of the field to the other, may benefit late ground nesting birds with chicks and other wildlife, such as young hares and deer.
Other management considerations
If appropriate, apply well-rotted farmyard manure (FYM) at low rates. To reduce loss of nutrients apply in late winter or early spring. FYM can have positive effects on insects and earthworms, which support a range of bird species such as yellow wagtails, skylarks and breeding waders.
Floristic diversity can be enhanced in a number of ways. Seed disperses naturally from adjacent habitats or germinates from the soil seed bank, arrives on domestic livestock and farm machinery, or can be introduced via farmyard manure spread sparingly in winter to avoid raising fertility levels. These can take many years to achieve visible results. The direct sowing/spreading of seed from another local source will speed up colonisation.
Supplementary feeding with hay may introduce more seed into the sward, as well as providing food for birds.