World’s Soil Resources

wind erosion 89 thousand ha; totally eroded lands cover about 10 percent of the territory of the country. In
Turkey, where 80 percent of soils are located on slopes steeper than 15 percent, the area affected by moderate,
severe and very severe erosion is 61.3 million ha, or 78.7 percent of the total area of the country; wind erosion is
active on about 500 thousand ha (Senol and Bayramin, 2013). The area of eroded soils in South Caucasus varies
between 35 and 43 percent of total agricultural lands, aggravated by the mountainous topography of the
region. In Central Asia as a whole, the total area affected by water erosion is over 30 million ha, and by wind
erosion about 67 million ha: in Uzbekistan up to 80 percent of agricultural land is affected by water erosion,
and in Tajikistan the area of agricultural lands affected by water erosion is estimated by different sources
at between 60 and 97 percent (CACILM, 2006). Long-term observations in Russia show that soil erosion on
average decreases the yield of leguminous crops by 15 percent, of wheat by 32 percent, of potatoes by 45
percent, and of perennial grasses by 25 percent (State Committee of Russian Federation on Land Resources
and Land Planning, 1999).
(2) Soil organic carbon change
Organic matter is a key component of soil, controlling many vital functions (Jones et al., 2011). The loss of
organic matter in soils is due both to erosion and to the increased rate of mineralization of organic carbon in
arable soils. Methodologically, it is difficult to separate erosion and mineralization-driven loss of humus in
soils. However, soils with negligible erosion loss commonly also lose organic carbon under cultivation. The
rate of soil organic matter loss differs between mineral and peat soils. In the latter group, soil degradation
after drainage may be fairly quick, producing an intensive flux of carbon dioxide to the atmosphere and in
places leading to complete mineralization of the organic layer and exposure of infertile underlying sediments.
This threat is discussed in detail in Section 11.4.3 below.
(3) Soil contamination
Due to more than 200years of industrialization, soil contamination is a widespread 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 three million. The issue is discussed in detail
below in Section 11.4.1.
(4) Soil acidification
Acidification involves the loss of base cations (e.g. calcium, magnesium, potassium, sodium) through
leaching and their replacement by acidic compounds, mainly soluble aluminum and iron complexes.
Acidification is always accompanied by a decrease in a soil’s capacity to neutralize acid, a process which is
irreversible in nature except over very long periods. Regulatory controls initiated in recent decades to mitigate
global warming have had a significant impact on the emissions of pollutants that cause acidification, mainly
by decreasing SO 2
emissions. By 2020, it is expected that the risk of ecosystem acidification will only be an
issue in some hot spots, in particular in the border area between the Netherlands and Germany (EEA, 2010a).
Recovery from acid deposition is characterised by decreased concentrations of sulphate, nitrate and aluminium
in soils. An increase in pH and acid-neutralising capacity (ANC) coupled with higher concentrations of base
cations would, in turn, improve the potential for biological recovery. However, given the delay in the response
of soil to decreases in acid deposition, many decades are likely to be required for affected sites to recover fully.
Additional information on trends in acidification is presented in the SOER 2010 Air Pollution Assessment (EEA,
2010a).
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in Europe and Eurasia