Soil — SOER 2010 thematic assessment

Summary

Soil is defined as the top layer of the earth's crust. It is composed of mineral particles, organic matter, water, air and living organisms — a non-renewable resource which performs many vital functions. Soil has a role as a habitat and gene pool; serves as a platform for human activities, landscape and heritage; and acts as a provider of raw materials. These functions are worthy of protection because of their socio-economic as well as environmental importance.

Soil degradation: state, trends and impacts

• Erosion: 105 million ha, or 16 % of Europe's total land area (excluding Russia), were estimated to be affected by water erosion in the 1990s. 42 million ha are affected by wind erosion.
• Organic matter decline: the soils of EU-27 Member States store about 79 billion tonnes of carbon. The storage capacity of soil is sensitive to climatic conditions and there is a high risk that global warming will turn soils into a major source of greenhouse gases. Some 45 % of soils in Europe have a low or very low organic matter content (meaning 0–2 % organic carbon) and 45 % have a medium content (meaning 2–6 % organic carbon). This issue is found especially in southern European countries, as well as in parts of France, the United Kingdom, Germany, Norway and Belgium.
• Compaction: the use of heavy machinery in agriculture can induce soil compaction. It reduces the capacity of soil to store and conduct water, makes it less permeable for plant roots and increases the risk of soil loss by water erosion. Estimates of areas at risk of soil compaction vary. Some authors estimate 36 % of European subsoils as having high or very high susceptibility to compaction. Other sources report 32 % of soils being highly vulnerable and 18 % moderately affected.
• Salinisation stands for the accumulation of salts and other substances from irrigation water and fertilizers which makes soils unsuitable for plant growth. It affects approximatly 3.8 million ha in Europe. The main driver is the inappropriate management of irrigated agricultural land.
• Landslides occur more frequently in areas with: highly erodible soils or clay-based sub-soils; steep slopes; intense and abundant precipitation; or abandoned terraces, such as the Alpine and Mediterranean regions. Until now there are no data on the total area affected in the EU.
• Contamination: due to more than 200 years of industrialisation, soil contamination is a wide-spread problem in Europe. The most frequent contaminants are heavy metals and mineral oil. The number of sites where potentially polluting activities have taken place now stands at approximately 3 million.
• Sealing occurs when agricultural or other non-developed land is built on. It normally includes the removal of top soil layers and leads to the loss of important soil functions, such as food production or water storage. On average, built-up and other man-made areas take up around 4 % of the total area in EEA countries (data exclude Greece, Switzerland and the United Kingdom), but not all of this is actually sealed. In the decade 1990–2000 the sealed area in the EU-15 increased by 6 %, and productive soil continues to be lost to urban sprawl and transport infrastructures.

• Biodiversity decline: soil biodiversity is built on a great variety of soil organisms from bacteria to mammals that shape the metabolic capacity of the ecosystem and many other functions of soils. Soil biodiversity is affected by all of the degradation processes listed above, and all driving forces mentioned apply (equally) to the loss of soil biodiversity.