Introduction
The JRC created a quantitative map of estimated soil pH values across Europe from a compilation of 12,333 soil pH measurements from 11 different sources, and using a geo-statistical framework based on Regression-Kriging. Fifty-four (54) auxiliary variables in the form of raster maps at 5km resolution were used to explain the differences in the distribution of soil pHCaCl2 and the kriged map of the residuals from the regression model was added. The goodness of fit of the regression model was satisfactory (R2adj = 0.43) and its residuals follow a Gaussian distribution. The lowest values correspond to the soils developed on acid rock (granites, quartzite’s, sandstones, etc), while the higher values are related to the presence of calcareous sediments and basic rocks. The validation of the model shows that the model is quite accurate (R2adj = 0.56). This shows the validity of Regression-Kriging in the estimation of the distribution of soil properties when a large and adequately documented number of soil measurements are available.
There is no consistent or harmonized soil profile database in Europe which allows for the generation of an overview of pH values across Europe using digital soil mapping techniques. Therefore, an attempt was made to combine, harmonize and QA/QC check values from 11 available databases in order to create a quantitative map of estimated soil pH values across Europe. It is realized that these databases reflect biased sampling strategies, non-precise coordinates, different sampling times (e.g. especially sensitive on agricultural soils) and many other factors which influence the predicted result. However, these databases represent a snap shot of available data on soil pH currently available in the European Soil Data Centre. The major distribution of soil pH with a reported quantitative uncertainty is described in order to determine the extent of the risk of acidification across Europe.
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Maps - Data
The map can be downloaded as a graphical file or as data.
Spatial coverage:25 Member States of the European Union where data available (Bulgaria and Romania are not included), Norway, Switzerland, Croatia, Albania.
File Type: Raster
Projection: ETRS89 Lambert Azimuthal Equal Area
Temporal coverage: 2009
Download the map: 
pH in Europe (Size: 0.5 MB, Format: PDF, Resolution: 100 dpi) or JPEG format, Low Resolution(96 dpi) or JPEG Format, High Resolution(300 dpi)
Download the data:
The data are provided as a raster (ESRI GRID), in the ETRS89 Lambert Azimuthal Equal Area Co-ordinate System; Temporal coverage: 2009. To get access to the data, fill in online form ; instructions will then follow how to download the data . A report will accompany the data. Warning: note that in this report, the spatial coverage includes Bulgaria and Romania, while the data provided do not include these countries.
Publication
The results of this study were published in Böhner, J., Blaschke, T., Montanarella, L. [Eds.] (2008): SAGA – Seconds Out. Hamburger Beiträge zur Physischen Geographie und Landschaftsökologie, Vol.19, 113pp. Download the publication
Contacts
Information: Marc Van Liedekerke, Panos Panagos
European Commission, Institute of Environment and Sustainability, Land Management and Natural Hazards Unit, Ispra, Italy.
Email:panos.panagos@jrc.ec.europa.eu, marc.van-liedekerke@jrc.ec.europa.eu
Work done by Hannes Isaak Reuter, Luis Rodriguez Lado, Tomislav Hengl & Luca Montanarella