Sustainable farming: getting the right balance

Grassland can be maintained as grassland as long as it is grazed or mown. Take away the sheep and cattle and most grassland will gradually revert to scrub and eventually to woodland. As the early farmers cleared more and more of the forest, grassland plant and animal populations boomed to become the major component of farmed land. However, by far the greater part of these farmed grasslands – with their native grasses and herbs – have themselves succumbed to the relentless march of agriculture.

Traditional grassland is damaged by a single application of mineral fertiliser or slurry and destroyed by successive applications. The grasses grow rapidly, ousting the wild flowers and with them the insects and birds once dependent on the annual cycle of grazing and mowing. Alternatively, much old grassland has disappeared under the plough to be replaced by arable crops or designer grassland, known as ‘ley’, made up of grasses specially bred for high productivity.

Traditional grassland supports fewer livestock but requires less fertiliser, other than that recycled from dung. This is released slowly and, to this day, the routes of the old drove roads and the stances where the cattle were held overnight remain in many places appreciably greener than the surrounding hills.

Grasslands which are still managed traditionally as pasture or meadow are the richest in wildlife.

Pasture

Pasture is grassland used for grazing, most commonly by sheep or cattle. In Scotland, pasture is the most widespread form of grassland management. But, if grassland is to be maintained in a healthy condition, a delicate balance must be achieved between undergrazing and overgrazing.

When a pasture is undergrazed, the first sign is often a build-up of plant remains known as ‘litter’; in extreme cases shrubs and trees may take over. Provided that pockets of grassland are left, undergrazing can be reversed by cattle. Their trampling and grazing breaks up the accumulated litter and lets in the light and warmth needed by grassland plants and animals.

Where a pasture is overgrazed, the grass may be cropped as smooth as a bowling green with only the unpalatable plants left standing. With severe overgrazing, the soil is exposed.

A combination of wet weather and trampling under the hooves of livestock can turn pasture into a quagmire. This process can be reversed if the ground is rested, though there is the risk that thistles and ragwort may colonise the drying mud in place of grass. Pasture with tussocks, tall herbs and the occasional tree or patch of scrub supports more creatures, such as spiders, insects, birds and mammals, than a sward of uniform height, as there are more places to feed and to shelter from predators and from the extremes of temperature and humidity.

Should grazing no longer be an option, cutting grassland can still provide a habitat for wildlife. In practice, since the cuttings must be removed to avoid smothering the growing shoots, this is only an option for limited areas.

Meadow

Meadows yield a crop of hay in summer to feed livestock over the winter. In spring the most productive pastures are ‘shut’ and, traditionally, the winter’s accumulation of manure, which is bulky and heavy, is spread over the fields closest to the byre. Here grassland can grow undisturbed by livestock.

Hay-making, as a way of managing grassland for winter feed, may only have been practised in Scotland for about 200-300 years. It represented a major advance in farming; before this, livestock which could not be kept over winter were slaughtered. Creating a meadow required little more than excluding the livestock from a pasture and leaving it to grow.

Mowing creates grassland of uniform height, which means that meadows support a more limited range of wildlife than pastures. However in most years, especially when the mowing is done later in the year, wildflowers are able to set seed and young birds to fledge before the grass is cut.

‘William Mackintosh of Borlum in 1729, advocating as a means of improving livestock the enclosing of farmland in Scotland by the planting of hedges, pointed out that such enclosing would not only make possible hay for winter food but would give some shelter for sheep in winter.’

Haldane (1952).

‘Haymaking is the chief preoccupation and business of the crofting year and its greatest glory. It is a long, complex and hazardous process, beginning in these parts about the middle of July – give or take a week or two, depending on how good the season’s growth is – and continuing usually into October or even November, Indeed I have known us to conclude our harvesting in December, more than once I have known that, and I have known it not to be concluded at all.’

Maclean (1984).

Ley

Leys are grasslands created by sowing agricultural strains of grasses, particularly rye grass, often together with clover. Bred for its high yield, rye grass depends on mineral fertiliser or slurry being applied so that it can maintain its high productivity. In the absence of fertiliser a ley will begin to revert; this does not mean a return to a more wildlife-rich grassland but rather a gradual infiltration of the ley by less demanding native grasses and rushes.

Like haymaking, silage making is a means of harvesting summer grass to feed livestock during winter, but it is a very much more intensive process. Whereas hay-making is usually limited to a single crop each year, two or three crops of silage can be produced from the same fast-growing ley, with the first being cut as early as May. This intensified activity prevents wildlife from colonising the ley.
Wildlife-friendly mowing (based on the corncrake-friendly moving illustration by Dan Powell (RSPB))

Modern mowing machines work inwards from the edge of the fields and corral birds and small mammals into a shrinking island in the centre, where many are killed by the final pass of the cutter. Wildlife-friendly mowing techniques reverse the mowing pattern. Cutting is started at the centre of the field and works outwards, driving grassland birds and mammals towards the edges of the fields where they have a chance of escaping the cutter’s blades. Many crofters and farmers have also agreed to delay their cutting in areas where birds like the corncrake are likely to breed.