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| Titel |
GEMAS: The continental scale influences on the pH of European agricultural and grazing land soil |
| VerfasserIn |
Clea Fabian, Clemens Reimann, Karl Fabian, Rainer Baritz, Edith Haslinger |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093264
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| Publikation (Nr.) |
 EGU/EGU2014-7846.pdf |
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| Zusammenfassung |
| The pH(CaCl2) values of all GEMAS soil samples were measured in a single run at the
NGU laboratory, Trondheim, between November 2009 and January 2010, thereby
providing the most homogenous existing soil pH data set on the European scale. pH is a
key variable for determining mobility and solubility of chemical elements in soil,
and pH also controls the adsorption capacity of clays. On a global scale, soil pH
closely mirrors climatic zonation, such that climate appears to be the predominant
influence factor on this scale. On continental, national, and on smaller scales it is of
crucial interest to assess the relative importance of geology, climate, soil formation,
and human activities on soil pH. The new GEMAS pH data set provides detailed
insight to the relevant processes in agricultural (Ap) and grazing land (Gr) soil on the
European scale, and defines a dependable background to calibrate studies on smaller
scales.
The European pH values show a bimodal distribution. A broad acidic mode with pH
between 4 and 6, and a sharp alkaline mode with pH between 7 and 8 due to the
Ca2+ buffer system, are clearly separated. The median pH is 5.8 for all GEMAS Ap
soils and 5.5 for the GEMAS Gr soils. Both data sets show a distinct North-South
gradient coinciding with the global climatic variation. Ap and Gr soil North of the
European border of ice age glaciation have median pH values of 5.2 and 4.8, whilst the
median values south of the border are 6.3 and 5.9, respectively. Although there is a
systematic increase in pH from sub-polar to Mediterranian climate, the new maps of
European soil pH indicate a close link between bedrock geology and soil pH. It
therefore appears that geology is the dominant direct controlling factor for pH,
while climate largely acts on large time scales by changing surface geology via
erosion, and on smaller timescales by influencing the mineralization of organic
matter.
In spite of the fact that pH is a strongly managed property in agricultural soil the GEMAS pH
maps mainly reflect natural conditions on the European scale, and not anthropogenic impact. |
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