Important new study shows the area of drained grassland peat soils is grossly overestimated
The land-use sector in Ireland is estimated in the national greenhouse gas inventory to be a major source of emissions that are projected to rise to 11.1 Million Tonnes CO2 eq per year by 2030*. Currently grassland peat soils are assumed to contribute up to 9 Million Tonnes CO2 eq of this total, due to the assumption that all 335,000 hectares are drained.
This estimate is highly uncertain and relies upon a number of assumptions regarding the drainage status, land classification, areal extent, nutrient status and the emission factors for agricultural peat soils. These assumptions are being tested by on-going research in the National Agricultural Soil Carbon Observatory and other research in the Teagasc Climate Centre to improve the emissions estimates and identify what farmers can do to reduce these emissions.
Results from an important Teagasc study published in the Journal of Environmental Management, on Thursday, 22 June, for the first time offers reliable evidence on the drainage status of grassland peat soils. The study establishes a range of likely scenarios with regard to actual drainage status of peat soils, which estimate emissions in the range of 3.6 – 4.7 M T CO2 eq, a saving of up to 60% on current inventory estimates. These values correspond to a drained area in the range of 90,000 to 120,000 hectares. The study focuses on the drainage status of agricultural peat soils and combines historical and recent data to offer new insights into the practices of peatland drainage, historical drainage efforts and likely efficacy at national scale.
Dr Pat Tuohy, Teagasc, explained, “while large areas of peatland have been transformed from their natural state to grassland agriculture, there is no evidence to support that effective drainage ever occurred on as much land as previously assumed. The drainage status of all grassland peat soils requires further investigation.”
Professor Owen Fenton, Teagasc, states, “This study has proposed these potential emission savings by compiling decades of evidence related to drainage status of peat soils. We uncovered data in national scientific literature and reports, which enabled a more accurate national figure for drainage status to be proposed.”
The application of these findings could impact significantly on the estimated emissions from grassland peat soils and more broadly on the land use, land use change and forestry sector (LULUCF), and this paper could support policy relating to these soils and their management. By accurately quantifying the impact of drainage status on these soils, Ireland can adopt targeted strategies to mitigate CO2 emissions and make informed policy decisions that contribute to a greener future. While this work offers the potential for positive changes in terms of LULUCF emissions, the refinement of other aspects, yet to be quantified, may result in increased emissions.
For Further Information visit
https://www.sciencedirect.com/science/article/pii/S0301479723011799?dgcid=author
Drainage status of grassland peat soils in Ireland: Extent, efficacy and implications for GHG emissions and rewetting efforts.
Authors: P Tuohy, L O’Sullivan, C.J. Bracken, O. Fenton