Ireland's State of the Environment Report 2024

153 Chapter 6: Soil Part D indicators: land take and soil sealing Soil sealing is the result of creating impervious surfaces for residential and commercial buildings and for infrastructure such as roads, rail and piers. The new national landcover map of Ireland indicates that 4% of Ireland’s soil is sealed. Longer term data from Corine Land Cover, although less detailed, show that soil sealing has doubled since 1990. In Ireland, the creation of sealed soils has occurred at the expense of agricultural land cover loss. Sealed soil is impervious to water, leading to run-off and a poor ability to help mitigate flooding. Soil sealing removes the ability of the soil biome to function, but it also impacts terrestrial biodiversity through the fragmentation of terrestrial habitats. The creation of hard surfaces, such as roads, can break habitats into smaller, unconnected parts, a process called fragmentation. This has a negative impact on access to food and on the genetic diversity of animal populations. The national biodiversity indicators rate habitat fragmentation in Ireland as ‘amber’ on a red-amber-green scale (NDBC, 2021). 5. Emerging aspects of soil health Microplastics in soil have been identified as an emerging threat to the world’s soils (FAO, 2021). They come from a variety of sources. Waste water and biosolids from waste water treatment plants are major sources (O’Kelly et al. , 2021; Nash et al. , 2023). Other sources include agricultural plastics, landfills, beach littering and urban run-off. These plastics can degrade into smaller microplastics that transfer into surface waters where the particles are absorbed by small aquatic animals and fish and their predators (Nash et al. , 2023). Research has examined the impact of microplastics on soil, soil fauna and plant growth. They have been found to affect soil chemistry, as they are carriers of heavy metals (O’Kelly et al. , 2021). Microplastics also have an impact on soil structure, which can change water dynamics (de Souza Machado et al. , 2018) and the enzyme activities of soil microbes (Yang et al. , 2021) and soil invertebrates (Huerta Lwanga et al. , 2016). Earthworms exposed to different concentrations of microplastics show lower growth rates and higher mortality rates in higher concentrations of microplastics (Huerta Lwanga et al. , 2016). This has implications for soil, as earthworms have a beneficial impact on its structure and aeration. Research into the effects of microplastics on soil ecosystems discovered reduced shoot height, changes in root structure, alterations in leaf composition and other impacts on plant growth, including lower seed germination rates, (Boots et al. , 2019; de Souza Machado et al. , 2019). The effects on plant growth were due to chemicals in the microplastics and their impact on soil structure and chemistry. 6. Conclusions Given the many vital services that we depend on our soils to deliver, from supporting food production and water purification to supporting ecosystems and production of raw materials, we have everything to gain from safeguarding the health of Ireland’s soils. Soil health is complex: it depends on the physical, chemical and biological attributes of soil. Unlike air and water, soil does not have specific overarching legislation to protect it. To address this, the EU soil monitoring law, proposed in July 2023, sets out indicators for soil health that Member States can use to assess soils and identify areas of poor soil health. Ireland’s primary source of soil information is the Irish Soil Information System. This identifies Ireland’s main soil classes. To implement the proposed soil monitoring law, Ireland will need to undertake an assessment of its soil health, using a soil sampling programme across defined soil districts. Achieving this assessment will fill evidence gaps. The kind of modelling capability illustrated by the EU Soil Observatory shows the opportunities offered by soil mapping and modelling to help us understand soil health. Ireland should take a cross-public sector approach to the advancement of soil mapping and modelling to rapidly improve our knowledge of soil health at a national level. The proposed EU law will also require the creation of a national contaminated sites register, which will be a welcome development in identifying potential hazards to human health. Addressing the threats to Ireland’s soil will have a positive impact on water quality, biodiversity and climate action as well as improving soil health. Different soil types offer different types of service and this diversity is enormously important in addressing different needs. Well-drained soils support agricultural production, whereas less productive soils can often store more carbon or support a more active soil biome. Detailed knowledge of Ireland’s soils would enable the appropriate use of different soil types according to the services they are best placed to provide.