The drainage of grassland peat soils in Ireland

Pat Tuohy, Senior Research officer at Teagasc Moorepark, is on this week’s Dairy Edge podcast to discuss the drainage status of grassland peat soils in Ireland.

Pat and his colleagues, Lillian O’Sullivan, Conor Bracken and Owen Fenton have recently released a review paper that when accepted into the national inventory by the EPA, will be of great significance in the Land Use, Land Use Change and Forestry (LULUCF) sector of carbon emissions.

Pat explains how it can be difficult to have the correct figures in this sector relative to others and gave examples of how you know how many animals are in the country, you know what quantity of diesel was burned and consequently, the figures for emissions are relatively robust. 

However, with Ireland being one of only three countries (Denmark and the Netherlands being the others) that are seen as net emitters of carbon from soil, work is ongoing to get better figures to feed into national inventories.

It is currently estimated that 345,000ha of land in Ireland is drained peat soils and this is releasing nearly 9.2 million tonnes of CO2 each year. Where there is no knowledge of drainage status, it must be assumed that all the land is drained. This is how the 345,000ha figure was arrived at and Pat and his colleagues conducted a review to see if this really was the case.

Pat went on to say that drains would need to be <5m apart to effectively drain peatland and the sheer cost would be uneconomical at great scale so that partial or localised drainage was more likely. 

Trawling through old survey documents gathered from Teagasc offices and labs down through the years, a substantial survey presented by Liam Galvin at a conference in the Netherlands in 1986 suggested that only 70,000 ha of these grassland peats were actually drained and that 20,000ha of this was now redundant. 

This combined with other surveys has allowed Pat and the others to arrive at a figure of 90-120,000 ha as being a more robust estimate of the actual area of drained grassland peats in the country.

While only 8-10% of the farms on the heavy soils programme would classify as grassland peat soils, the implications are still significant because as well as reducing the emissions associated with these soils from >9 million to nearly half that, it may also have implications under the Land restoration laws that are being proposed.

Pat finishes by explaining that work will continue on many fronts to improve and further refine figures for both land areas but also emission factors mentioning the role of the National Agricultural Soil Carbon Observatory (NASCO) which will be working in particular on establishing better emission estimates for many land types under different management conditions across the country.  

For more episodes from the Dairy Edge podcast go to the show page at: 

https://www.teagasc.ie/animals/dairy/the-dairy-edge-podcast/

The Dairy Edge is a co-production with LastCastMedia.com