The practice of agriculture is closely intertwined with Irish karst landscapes. Farming communities are dependent on the area's characteristic soil and water resources, and agricultural practices may themselves alter the nature of these resources.
In their most extreme forms, karst landscapes can be extremely difficult to farm, as any visitor to the Burren or the Aran Islands can readily appreciate; the bare rocky surfaces have virtually no soil or water. Where there is a little more soil cover developed on a more crumbly limestone layer, as in the upland pastures of the Burren, there may be good winter grazing but in summer, grass growth may be inhibited by a lack of water. Even karst areas with a deeper soil cover may have water supply problems: the water table may be very deep, so streams and springs may dry up in summer and the grass may die back.
The famed Burren flora, found on a patchy mosaic of soil and rock, is not entirely a natural phenomenon. In the absence of traditional grazing activities, the famous flower meadows become colonised by hazel scrub. Indeed, the patchy soil cover is itself at least partly a consequence of agriculture, as previously described: clearance of the forest cover for agriculture in prehistoric times resulted in soil erosion.
In the Aran Islands, there is a long tradition of creating soil on the bare limestone by collecting seaweed and sand and spreading them on the fields or in lazy-bed ridges. In the Burren, the creation of smooth, soil covered fields from rocky scrubland has become a widespread practice to facilitate agricultural modernisation. Grant-aided reclamation has involved scrub clearance, bulldozing of loose boulders and stone walls, and spreading of topsoil to make the land suitable for silage production. A balance needs to be achieved between agricultural needs and environmental and heritage considerations.
A reclaimed area in the Burren (David Drew)
Silage clamp on bare karstic limestone (David Drew)
While upland karst areas such as the Burren plateau may suffer from a shortage of water for summer grass growth and for human and animal consumption, low-lying karst areas such as the western lowlands may suffer from periodic excesses of water. The seasonal flooding of turloughs brings the advantage of annual liming of the pasture on the turlough floor, but nevertheless many turloughs have been artificially drained to provide grazing over a longer period of the year. Occasionally, extensive flooding takes place in karst areas beyond the normal turlough winter flooding limits. In the Gort-Kinvara area, this has given rise to problems for agricultural land use, as well as flooding roads and houses for many weeks. As with the upland dry karst pastures, a balance needs to be achieved in the turlough areas between agricultural and conservation needs.
Agriculture can also have an influence on water quality in karst areas. If agricultural wastes are badly handled, they may give rise to pollution of springs and wells. Silage effluent can easily pass through open fissures into drinking water supplies if it is not properly contained. The recent move to silage bales rather than silage clamps in the Burren is minimising this risk. Particular care must also be taken with slurry storage to avoid leakages, and landspreading of slurry should avoid areas where the soil cover is thin. Farmyard runoff needs to be collected and landspread only in suitable areas.
To summarise, agricultural activity is an integral feature of Irish karst landscapes and the challenge for the future is to achieve an economically and environmentally sustainable livelihood in these areas.