European soil database

The Eurpoean soil database (ESDB) is the main data reference for soil data collected at European level during the last 20 years. It is also the main source of information from which most other data sets and services are derived.

The ESDB contains four discrete datasets:

1. the Soil Geographical Database of Eurasia at scale 1:1,000,000 (SGDBE), a digitized European soil map and related attributes;
2. the Pedotransfer Rules Database (PTRDB), the results of the application of the pedotransfer rules to the SGDBE are delivered as a table with new attributes related to the European soil map;
3. the Soil Profile Analytical Database of Europa (SPADBE), delivered as tables;
4. the Database of Hydraulic Properties of European Soils (HYPRES), delivered as a set of Word documents.

Data are available at various scales. For instance, the “European Soil Database v2 Raster Library” contains raster (grid) data files with cell sizes of both 1km x 1km and 10km x 10km for a large number of soil related parameters. The 10km x 10km rasters are in the public domain and allow expert users to use the data for mapping and modelling. The 1km x 1km rasters are available after a prior registration. The soil raster data files are accompanied by static soil maps (PDF-format, A3), which allow the user to have a quick overview of the distribution of soil characteristics. The data can also be viewed and interrogated using an interactive map viewer.

The Soil Geographical Database of Eurasia at scale 1:1,000,000 (SGDBE), version 4 beta

The Soil Geographical Database of Eurasia provides 1:1,000,000 coverage of soil distribution and properties for the Eurasian region. Soil classification is based on the terminology of the F.A.O. legend for the 1:5 million scale Soil Map of the World. The area covered comprises:

Albania, Austria, Belarus, Belgium, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, FYROM (Former Yugoslav Republic of Macedonia), Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Malta, Moldova, The Netherlands, Norway, Poland, Portugal, Romania, Russian Federation, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Ukraine and the United Kingdom. Work is ongoing to incorporate soil data for other Mediterranean countries: Algeria, Egypt, Jordan, Lebanon, Morocco, Palestine, Syria, Tunisia and Turkey.

Potential uses include spatial data query, extraction and thematic mapping, and soil spatial data layer input to agro-environmental models (e.g. soil erosion risk, yield forecasting).

The database contains a list of Soil Typological Units (STU). As well as the soil name, each unit is described by variables (attributes) representing important properties of the soil profile - e.g. depth, texture, stoniness, water regime. At a 1:1 million scale, it is not feasible to delineate the STUs, so these are grouped into Soil Mapping Units (SMU) for mapping purposes. Each SMU represents a soil association, comprising an integrated pedological system within the landscape. In the STU table, each Soil Mapping Unit has a number of attributes. For the values of some attributes a measure of the ‘confidence’ in the value is given (high, moderate, low or very low). Maps are also available, giving views of the geographical database. Generally, there is one "thematic map" per STU table attribute and two accompanying maps expressing the purity and confidence level. It is important to note that the thematic maps are "dominant value" maps.

A more detailed description of the database is given in the SGDBE, while the SGDBE Dictionary explains the data structures (in the Arc/Info GIS software environment) and SGDBE Attricod provides a list of the reported attributes with their accepted values.

The database is currently managed using the ArcGIS® Geographical Information System (GIS) software system and associated relational databases.

The Pedotransfer Rules Database (PTRDB), version 2.0

This report presents a method to translate data stored in the SGDB database to data needed for environmental purposes. The method is based on the concept of a pedotransfer function. Due to the qualitative nature of the SGDB data, these functions are simple tables and are called pedotranfer rules.

Pedotransfer rules link the standard soil characteristics to more complex properties (for practical purposes), such as hydro-dynamic properties. The rules appear in a standardized format which facilitates their use and management. These are based on expert judgement, mainly qualitative, and assume that a due weight is given to the confidence level of individual inferred attributes. The results provided by the application of these rules are therefore only qualitative estimates. At the 1:1,000,000 scale it is difficult to provide accurate information from the few data contained in the Soil Database, so methodological limitations of the approach needs to be recognised. This is done by attaching a confidence level to each output value, which can highlight those areas for which the results are not so reliable. Likewise, rules are applied to Soil Typological Units (STU) and when their results have to be displayed as maps, purity of the Soil Mapping Units (SMU) has to be taken into account. This can be computed from an indicator of the surface percentage of STUs within each SMU which is provided in the database. A set of tools has been developed within Arc/Info to manage and use the rules database.

The application of the pedotransfer rules from the PTRDB to the SGDBE results in a table that contains for each STU a set of values for each STU. These output attributes correspond to the environmental parameters considered to be relevant for the specific task: e.g., hydrology of soil types for predicting catchment response to rainfall and standard percentage of run-off; location and sensitivity of wetlands; soil buffering capacity for predicting soil susceptibility; ecosystem and surface water deposition; vulnerability of ground -and surface- water to pollution by agrochemicals and farm waste; soil erosion potential, etc.

The Soil Profile Analytical Database of Europa (SPADBE), version 2.1.0.0

The Soil Profile Analytical Database (SPADBE) is designed to enhance information about soils in the SGDBE. It contains soil profile characterisations with physical and chemical analyses. Because of problems of data harmonisation and confidentiality, two different kinds of profile data are provided:

• Measured soil profile data are provided where available, relating to georeferenced soil profiles that have been described and sampled in the field, and analysed in the laboratory. For measured profiles, the analytical methods are coded and missing values identified; for estimated profiles the analytical methods are defined to facilitate trans-national comparisons. .
• Estimated soil profile data are based on expert judgement and represent the modal conditions for the STU.

The database includes standard soil property data for each horizon. Attributes include:

• parent material
• soil texture
• bulk density
• root depth
• soil water properties
• organic matter content
• structure
• pH
• cation exchange characteristics
• total nitrogen content
• calcium carbonate content
• calcium sulphate content
• electric conductivity
• cation exchange capacity and exchangeable bases

The data are provided as a set of spreadsheets (Proforma I). Since the gathered data were quite heterogeneous, hardly any attempt has been made to harmonize the data which are delivered as received. A table that holds the estimated profiles (Proforma II) is also available. An attempt has been made by the data provider or the data compiler to link each profile to an existing STU; however some profiles could not be linked. Note that estimated profiles are not geo-located.

The Database of Hydraulic Properties of European Soils (HYPRES), version 1.0

A major obstacle to the wider application of water simulation models is

The HYPRES database was developed to overcome the lack of easily accessible and representative data on soil hydraulic properties. It contains information on a total of 5521 soil horizons. Each soil horizon was allocated to one of 11 possible soil textural/pedological classes derived from the 6 FAO texture classes (5 mineral and 1 organic) and the two pedological classes (topsoil and subsoil) recognised within the 1:1,000,000 scale Soil Geographical Database of Eurasia. Then, both categorical and continuous pedotransfer functions were developed. The categorical pedotransfer functions were used in combination with the 1:1,000,000 scale Soil Database of Europa to determine the spatial distribution of soil water availability.

The HYPRES Database contains only metadata, the actual functions and function parameters. It does not contain the source data and results, as no agreement has been reached with the participating institutions regarding their distribution.