Information and Advisory Note Number 8                                                Back to menu

Grazing management—unimproved and herb rich pasture

1. General guidelines

1.1 Grazing can be important in keeping swards open enough to allow seed germination and establishment, but levels of nutrient inputs should not be increased.

1.2 Most plants and animals benefit from a grazing regime in which there is "a mouthful left when stock are taken out". Take what the field has to offer then move on to another pasture before damaging the sward.

1.3 Maintain or encourage a range of plant structures including short sward, tall herbage, scattered grass tussocks and limited areas of bare ground to support as wide a range of insects and birds as possible.

1.4 Maintain or encourage a wide variety of plants.

1.5 Leave up to 5% total area of field—e.g. field comers, ditch sides and iris beds— ungrazed to provide early spring cover for birds and other wildlife, if necessary by fencing from regularly grazed areas. Electric fencing can provide a cheap way of keeping cattle out and allowing areas to grow rank—it can be easily removed to allow later grazing to prevent scrub developing.

1.6 Take particular care not to overstock in wet periods or in winter which may lead to break-up of the sward and colonisation by aggressive weed species, e.g. creeping thistle and broad-leaved dock.

1.7 Avoid supplementary feeding on unimproved grassland which can lead to poaching and localised enrichment due to dunging—4his can damage the sward, reduce plant diversity and introduce weeds. Troughs can be used for feeding concentrates, provided they are moved on before the area around them becomes damaged.

1.8 Wherever possible avoid grazing stock treated with ivermectin on unimproved grassland. Ivermectin is excreted largely unaltered in dung, so it remains powerfully insecticidal. This reduces the number and variety of insects in dung, thereby slowing down its decomposition which can lead to a reduction in food resources for insectivorous birds such as curlew and chough. Bolus formulations result in ivermectin being excreted in dung over a longer period of time. Where ivermectin is used, pour-on or injected formulations are therefore preferable.

2. Stocking density

2.1 The following stocking rates are intended as general guidelines based on average stocking rates over the year as a whole. Proportionately higher stocking rates may be acceptable for seasonal grazing in line with the recommendations given on timing. Calcareous grassland—0.5 LSU/ha; neutral grasslands—1 LSU/ha; acid grasslands—0.4 LSU/ha. (1 LSU = 1 cow or 6 medium sized sheep).

2.2 Shut-up periods are a less attractive alternative if higher stocking rates over the whole year are necessary—these periods can be timed to benefit the most important plant species present.

2.3 An increase in the amount of uneaten grass, the accumulation of litter, an increase in vigorous rank and unpalatable grasses, and
a reduction in low-growing herbs indicates undergrazing (i.e. stocking density too low)

2.4 A reduction in diversity of plants, excessive poaching, weed invasion and the development of bare patches indicates overgrazing (i.e. stocking density too high).

2.5 Low summer stocking density is important to allow plants to flower and set seed.

3. Timing

3.1 The plants and wildlife associated with each area of grassland will have evolved according to past management. Meadows grazed in early spring, shut up for hay from May-July/August and then re-opened for grazing of the aftermath after taking a hay crop, are likely to be dominated by summer flowering species, whereas pasture which has been summer-grazed for many years is likely to be dominated by spring flowering species. Maintenance of long-standing management regimes is therefore usually beneficial, but bear in mind the following points.

• Early spring grazing has minimal damaging effect on wildlife, but is ideal for controlling coarse grasses such as mat grass which are unpalatable at other times. However, grazing too early can result in serious poaching.
• The eggs of ground nesting birds are vulnerable to trampling and early season flowers are readily damaged/eaten during late spring, so low stocking densities are particularly important during this period.
• Heavy summer grazing reduces opportunities for plants to flower and set seed, which may lead to loss of plant species. It also reduces the availability of pollen and nectar for insects, most notably butterflies, which live and feed on flowers and seed-heads. Consequently, heavy summer grazing of herb-rich grassland should be avoided.
• Autumn grazing is ideal as it creates a short sward for grazing by geese and wildfowl, and probing for insects by chough and waders, but is unlikely to affect seed production.

4. Type of livestock

4.1 Sheep are more selective feeders than cattle. Unless stocked at high density, sheep grazing therefore results in short-cropped areas of palatable vegetation interspersed with ungrazed areas of rank growth. Sheep are also more likely to eat flowers, which may affect seed production and the abundance of invertebrates.

4.2 Cattle eat a wider range of coarser plants than sheep so that the effect of grazing is more evenly spread, and cattle are better able to break up a mat of accumulated plant litter. Trampling by cattle is more likely to expose bare soil which may damage archaeological features and marshy ground. However, moderate cattle trampling creates sites for seedling establishment which are essential for maintaining and improving botanical diversity.

5. Nutrient inputs

5.1 Artificial fertiliser, farmyard manure and slurry should not be applied to areas of unimproved and herb rich grassland used for grazing.

5.2 Lime should only be applied as required and never apply more than 3 tonnes/hectare of calcium oxide (CaO) equivalent.

6. Harrowing

6.1 Harrowing should only be carried out before ground-nesting birds have established their nests—ground conditions permitting.

Further Reading

Andrews, J. and Rebane, M. (1994). Farming and wildlife—a practical management handbook. RSPB

Crofts, A. and Jefferson, R.G. (1994). The Lowland Grassland Management Handbook. English Nature/The Wildlife Trusts.

Authors

Daniel Gotts, Agricultural Landscape Ecologist

Vyv Wood-Gee
Countryside Management Consultant
Scabgill
Braehead
Lanark, ML11 8HA

Jane MacKintosh, Grassland Ecologist

Contacts for advice and information:

Jane MacKintosh, Daniel Gotts

Research and Advisory Services Directorate
Agriculture and Woodland Environments
Branch
2 Anderson Place, Edinburgh, EH6 5NP
Tel: 0131-447 4784
 

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