Soil carbon

Overall, EU soils are losing carbon. In 2019, Member States reported net emissions of 108Mt CO₂ from organic soil and net removals of 44Mt CO₂ from mineral soil. The organic soils under cropland and grassland that are responsible for most of the emissions constitute 1.1% of the total area with cropland and 3.8% of the total area with grassland. (see Figure 5). The picture is, however, mixed depending on soil type and management practices; it is possible for the same type of land use to lose carbon in one Member State and increase carbon stocks in another. This is due to differences in management and, in particular, changes in management that have an impact on the gain and loss of carbon for several years after the change.

The area of organic soils decreased by 0.46Mha during the period 1990-2019. This typically happens when a soil with a shallow layer of organic matter has been drained for a number of years and consequently loses so much carbon that it becomes a mineral soil.

As organic soils have a larger impact on overall emissions than mineral soils per hectare, this decrease in the area of organic soils, together with a decrease in the cropland area (see Figure 6), has reduced overall emissions from soils in the EU since 1990.

Figure 6. Area of each land use category in the EU in 1990 and 2019 (kha)

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While the areas of cropland and grassland with organic soil amount to only 1.3 million hectares and 2.8 million hectares, respectively (see Figure 2), these soils are responsible for 71% of the GHG emissions from organic soil. The larger area of organic soil used for forest land and wetlands together is responsible for only 26% of total emissions from organic soil. 

Figure 7. Emissions from organic soil by Member State (kt CO₂)

Note: 20 EU Member States reported emissions from organic soils.
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Germany is the Member State with by far the most emissions from organic soil (see Figure 7). This corresponds well with the country’s area of organic soil under cropland and grassland. Germany, Finland, Ireland, Sweden, Latvia, the Netherlands and Denmark together report 89% of the total EU emissions from organic soil.

Greenhouse gases other than CO₂

In addition to CO₂, CH₄ and N₂O are the two other GHGs associated with soil management. Both have a global warming potential larger than CO₂. According to the IPCC fourth assessment report, 1t of CH₄ corresponds to 25t CO₂, while 1t N₂O corresponds to 298t CO₂. N₂O emissions are generally due to the addition of nitrogen to the soil, such as input from fertilisers, manures and crop residues and loss of carbon due to changes in management and drainage of organic soil. CH₄ emissions are linked to the decay of organic material under anaerobic conditions, which arise when drained soil is rewetted. Both gases are also emitted during the burning of biomass^[2]. For the inventory year 2019, Member States reported emissions of 2.32Mt CO₂e and 4.45Mt CO₂e for CH₄ and N₂O, respectively, as a result of drainage and rewetting of organic soil. Member States reported 13.16Mt CO₂e for N₂O emissions from the cultivation of histosols in the agricultural sector.

Management of soils has wide implications for achieving EU environment policies

The EU has set a legally binding target of climate neutrality in 2050 and this includes an important role for the LULUCF sector including soils in reducing overall EU emissions.  Besides the role of soils in climate change mitigation policy, soil management decisions will also impact other policy areas such as the biodiversity, the soil and the farm to fork strategies, so it is important to understand synergies and trade-offs between environmental impacts of climate-related soil management measures.

The IPCC 6th Assessment Report on mitigation of climate change mentions afforestation, enhanced sequestration in cropland and grasslands, use of biochar, peatland and costal wetland restoration and agroforestry as mitigation options with a positive impact on soil carbon storage. Depending on the measure and the implementation there can be important co-benefits such as improved soil quality, nutrient recycling, resilience to drought, increased crop yields, improved biodiversity and reduced N₂O and CH₄ emissions.

Trade-offs also depend on the specific measure and how it is implemented and can result in increased competition for land when measures have negative impacts on food production and on biodiversity, and increase N₂O and CH₄ emissions as well of the risk of subsequent loss of sequestered carbon due to climate change and future disturbances (IPCC, 2022).

Management practices that reduce emissions of one GHG, and in some cases increase another GHG, underscore the importance of having scientifically sound methods for estimating the net GHG impact of land use management practices, as well as the impact of the same management practices on nature restoration.