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Arable field margins |
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Managing arable field margins
Creating grass marginsAutumn (August/September) is the best time to establish grass margins; use a higher seed rate if sowing in spring. Leave an area to regenerate naturally if a perennial grass sward will develop; otherwise drill a native seed mix. Spray a heavy weed burden with glyphosate or glufosinate before cultivation. Cut the sward when it is 10 cm tall in the first summer to control weeds and encourage grasses to tiller; this may require three cuts. Swaths of cut grass lying on top of the sward may suppress perennial grasses. Wide margins act as 'buffer strips', reducing the drift of pesticides into watercourses, and so help farmers comply with pesticide label requirements. Avoid herbicides and fertiliser drifting into the margin as these will benefit competitive weeds over perennial grasses. Insecticide drift harms any beneficial insects supported by the field margin. Treat barren brome in the grass margin selectively with an application of fluazifop-P-butyl in November (most perennial grasses will recover from this treatment). Retain the grass margins and apply no fertiliser when a grass ley forms part of the arable rotation. Ideally avoid grazing the margins from March to August. Types of grass marginThe tussocky type helps ground-nesting birds; and the wild flower type attracts nectar-feeding insects (see below). You may prefer to leave a sterile strip around the crop edge to control weeds, although if you establish a perennial grass margin between a hedge base and the crop this should not be necessary. Where you use such strips, however, they should be positioned between the grass margin and the crop. Tussocky grass margins for nesting birds and over-wintering insectsOne- or two-metre margins, next to short, thick hedges, or boundaries with no hedge at all, provide nesting cover. Up to 30% of cocksfoot or timothy grass in the mix will create a tussocky sward ideal for nesting cover and protection for over-wintering insects. The mix should also include fine grasses such as fescues and bents. Cut these margins once every three years after the first year, and only in the autumn. Avoid cutting all margins during the same year. For 6-metre margins, cut the 3 metres abutting the crop edge annually, but only cut the hedgeside margin every three years; this will create a useful mix of grassland structure. Wild flower margins to attract nectar-feeding insectsCreate wild flower strips within a 6-metre margin in a sunny area. Well-used farm tracks and footpaths are good sites as these areas are disturbed too often to make them suitable for the tussocky margins that suit nesting birds. Use a mix of fine grasses, such as fescues and bents. Wild flower seed should comprise between 5% and 20% of the mix by weight and include native plants such as yarrow, knapweed and ox-eye daisy. Where possible, use a local seed source. Seek advice to find out if there is local seed available. Drill the grass seed and broadcast the wild flower seed before rolling. Cut annually in the autumn. Cultivated margins for rare arable plantsThis type of management is ideal for those sites with rare arable plant species or communities. Grass margins on these sites will suppress the germination of these dwindling populations. These plants need cultivation, and protection from herbicides and fertilisers. Cultivate the margin annually and leave it to regenerate without broad-spectrum herbicides or fertiliser. The germination time of the key plant species present will dictate the cultivation time. This type of management can give farmland birds a summer seed source on sites where any resultant weeds will not compromise the adjacent crop (such as on light, low nutrient soils). |
Insect on dewy ears of barley - Andy Hay (rspb-images.com)
Herd of cows, West Sedgemoor RSPB reserve - David Kjaer (rspb-images.com, Ref: D_2006_11413_0029)
Archie Carmichael (L, on tractor) & Gus Keys (R = site manager) in farm yard at Kinnabus. Mull of Oa RSPB reserve. Islay - Andy Hay (rspb-images.com, Ref: D_2005_9857_009)