March 2001 Three NUI Galway Researchers Honoured

Three National University of Ireland, Galway (NUI, Galway) researchers have been honoured for excellence in natural resource conservation and environmental protection. The researchers measured the amount of erosion resulting from sheep grazing peat hillsides in western Ireland. Rain can wash sediment from such erosion into streams, threatening water quality and spawning grounds of wild Atlantic salmon.

John Mulqueen, of Teagasc, who is based in the University and Michael Rodgers and Niall Marren, of NUI, Galway s Civil Engineering Department, describe their findings in a technical paper, Erosion of Hill Peat in Western Ireland. Their paper has received the 2001 Most Distinguished Technical Paper Award, from the International Erosion Control Association (IECA).

Dr. Michael Rodgers accepted the award on behalf of all three researchers during formal ceremonies at the recent 2001 IECA conference in Las Vegas, Nevada, Nearly 2000 erosion control professionals from around the world attended the conference. The award is made to a scientific paper that contributes most to advancing erosion control knowledge and also recognises concise, clear technical writing, which presents innovative solutions to erosion control problems.

The NUI, Galway research, the first of its kind involving peat hillsides, was prompted by concerns that increased stocking rates of sheep could accelerate erosion. Grazing by more sheep could remove too much soil-protecting vegetation and increased foot treading on paths could loosen the peat soils, leaving them more vulnerable to the erosive impact of raindrops and to runoff. The two-year field study involved an 8-hectare Leenane subcatchment of the Erriff River on a Teagasc research farm at Glendavock townland (Co. Mayo). Many slopes on the farm have gradients of 9% to 18%. Average annual rainfall, about 2,500 mm, is among the highest in Ireland. In addition to the field studies at Leenane, the researchers conducted laboratory tests on undisturbed slabs of peat from Leenane and three other sites at Maam, Croagh Patrick and Newport at the Environmental Engineering and Soil Mechanics Laboratories at NUI, Galway.

In the laboratory tests the researchers varied the slope and simulated the type of soil disturbance caused by sheep traffic. They found that annual peat sediment losses at the Leenane hill farm averaged 278 kg per hectare with a stocking rate of 0.9 Scottish Blackface ewes per hectare. In the laboratory trials, the virgin peats at Leenane and Maam were very resistant to erosion, while virgin peats from both Newport and Croagh Patrick were erodible.

According to the researchers, this study suggests that overstocking, primarily through excessive sheep traffic damaging the peat and weathering of shallow peat, increases the likelihood of erosion. Removal of vegetation, per se, by grazing has less impact on erosion because of the strength of the peat's fibrous top layer.For hill peat farming, the sustainable sheep-stocking rate depends on the proportion and strategic use of greenland available. Under the management system at Leenane, this stocking rate is 0.9 ewes per hectare.

To reduce erosion, sheep access areas and corridors should be changed from time to time. If heavily treaded with little vegetation, these areas should be fenced off to allow for recovery of the peat surface and re-establishment of vegetation.

The research was financed, in part, by European Union Structural Funding through Teagasc. The IECA, founded in 1972, is a non-profit professional organisation, with members in 56 countries around the world who are dedicated to minimising accelerated soil erosion. This is the tenth year of the annual IECA Environmental Excellence Awards programme.

Information from: Máire Mhic Uidhir, Press Officer, NUI, Galway. Tel. 091 750418