Ireland's State of the Environment Report 2024

149 Chapter 6: Soil Figure 6.7  Schematic of carbon sources and sinks CO 2 Uptake CO 2 Release If CO 2 uptake is higher than CO 2 released = carbon sink If CO 2 uptake is lower than CO 2 released = carbon source CO 2 Release CO 2 Uptake Source: Adapted from Teagasc, 2020b 2 sites.google.com/view/project-repeat/home Soil erosion. The EU Soil Observatory identifies four drivers of soil erosion: water, wind, harvest and tillage. Of these four, tillage erosion and water erosion are the two most prevalent in Ireland, based on the EU Soil Observatory model, with wind erosion confined to small coastal areas. Harvest erosion occurs when soil that adheres to crops or rock fragments is removed during harvesting; it is more prevalent during the harvesting of root and tuber crops than other crops. Harvest erosion is lower in Ireland than in other EU Member States, as our land use for crops is relatively low (Ireland’s agricultural land use is predominantly grassland). Tillage erosion occurs in the east, south-east and south where tillage activity is more widespread. The EU Soil Observatory model has identified greater potential for water erosion in areas of higher altitude (including uplands in Wicklow, Cork, Kerry, Galway and Donegal). Soil loss by water erosion in Europe is expected to increase as climatic conditions change. An assessment of different land use and climate change scenarios predicts an increase in soil erosion but at relatively lower rates in northern European countries such as Ireland than in southern Europe (Panagos et al. , 2021). Loss of soil organic carbon. Soil organic carbon improves soil productivity and water retention and acts as an important carbon sink. Teagasc research shows that clay soils have a higher carbon sequestration capacity; however, ploughing can increase carbon loss and, in a dry year, soils can switch from being carbon sinks to sources of carbon emissions (Figure 6.7). Soil organic carbon is affected by soil management regimes, fertilisation and animal stocking rates (Teagasc, 2020). Grasslands on mineral soil can be a carbon sink and grasslands on drained peat soils are a substantial carbon source (Teagasc, 2020). Soil organic carbon stocks are influenced by short- term changes between cropland and grassland and by soil disturbances. The Environmental Protection Agency (EPA)-funded Soil Organic Carbon and Land Use Management (SOLUM) project examined methods for accurately measuring soil organic carbon in Ireland (Saunders et al. , 2022). The EU Soil Observatory has identified peatlands in Europe that are within a fixed radius of croplands to ascertain the risk of peatland degradation. This model identified 62% of Ireland’s peatlands at risk of degradation. Corine (Coordination of Information on the Environment) Land Cover data, while coarser in resolution, offers longer term trend information and indicates that Ireland’s peatlands decreased by 22% between 1990 and 2018. This figure does not account for peatlands lost before 1990, or since the establishment of the Bog Commission in the early 1800s. Further research, the RePeat project, 2 is mapping the extent of peatlands using Bog Commission maps and advanced geospatial and Earth observation techniques. Peatlands are unique ecosystems and can sequester large amounts of carbon dioxide, so they are an important element of Ireland’s climate mitigation efforts (Figure 6.8). Peatland degradation is a result of peat extraction for energy and horticultural use and of drainage for agricultural, forestry or settlement use.