Introduction to the European Soil Database (distribution version v2.0)
The European Soil Database (distribution version v2.0) consists of a number of databases:
- the Soil Geographical Database of Eurasia at scale 1:1,000,000 (SGDBE), which is a digitized European soil map and related attributes (version 4 beta)
- the PedoTransfer Rules Database (PTRDB), version 2.0, which holds a number of pedotransfer rules which can be applied to the SGDBE ; 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
- the Soil Profile Analytical Database of Europa (SPADBE), version 2.1.0.0, delivered as tables
- the Database of Hydraulic Properties of European Soils (HYPRES), version 1.0, delivered as a set of Word documents
In this introduction, an overview will be given of these components, while in Advanced Access to the Soil DB each of them is discussed in detail, including all implementational aspects within the Arc/Info GIS software environment.
Soil Geographical Database of Eurasia at scale 1:1,000,000 (SGDBE), version 4 beta
The Soil Geographical Database of Eurasia at scale 1:1,000,000 is part of the European Soil Information System (EUSIS). It is the resulting product of a collaborative project involving all the European Union and neighbouring countries. It is a simplified representation of the diversity and spatial variability of the soil coverage. The methodology used to differentiate and name the main soil types is based on the terminology of the F.A.O. legend for the Soil Map of the World at scale 1:5,000,000. This terminology has been refined and adapted to take account of the specificities of the landscapes in Europa. It is itself founded on the distinction of the main pedogenetic processes leading to soil differentiation: brunification, lessivage, podzolisation, hydromorphy, etc.
The database contains a list of Soil Typological Units (STU). Besides the soil names they represent, these units are described by variables (attributes) specifying the nature and properties of the soils: for example the texture, the water regime, the stoniness, etc. The geographical representation was chosen at a scale corresponding to the 1:1,000,000. At this scale, it is not feasible to delineate the STUs. Therefore they are grouped into Soil Mapping Units (SMU) to form soil associations and to illustrate the functioning of pedological systems within the landscapes. Each SMU corresponds to a part of the mapped territory and as such is represented by one or more polygons in a geometrical dataset.
Harmonisation of the soil data from the member countries is based on a dictionary giving the definition for each occurrence of the variables. Considering the scale, the precision of the variables is weak. Furthermore these variables were estimated over large areas by expert judgement rather than measured on local soil samples. This expertise results from synthesis and generalisation tasks of national or regional maps published at more detailed scales, for example 1:50,000 or 1:25,000 scales. Delineation of the Soil Mapping Units is also the result of expertise and experience. Heterogeneity can be considerable in European regions. The spatial variability of soils is very important and is difficult to express at global levels of precision. Quality indices of the information (purity and confidence level) are included with the data in order to guide usage.
As a result, the SGDBE consists of both a geometrical dataset and a semantic dataset (set of attribute files) which links attribute values to the polygons of the geometrical dataset. How map polygons, SMU's and STU's are linked together is illustrated in the figure below:
In the STU table, each STU has a number of attributes: an overview of these attributes is given below. It is important to know that values for an attribute A are chosen among a set of defined classes for that attribute; these values are documented in SGDBE Attricod, also available as .doc file [470Kb].
| Attribute Name | Confidence Level | Short description |
|---|---|---|
| AGLIM1 | - | Code of the most important limitation to agricultural use of the STU |
| AGLIM2 | - | Code of a secondary limitation to agricultural use of the STU |
| CFL | - | Code for a global confidence level of the STU description |
| FAO85-FULL | yes | Full soil code of the STU from the 1974 (modified CEC 1985) FAO-UNESCO Soil Legend |
| FAO85-LEV1 | yes | Soil major group code of the STU from the 1974 (modified CEC 1985) FAO-UNESCO Soil Legend |
| FAO85-LEV2 | yes | Second level soil code of the STU from the 1974 (modified CEC 1985) FAO-UNESCO Soil Legend |
| FAO85-LEV3 | yes | Third level soil code of the STU from the 1974 (modified CEC 1985) FAO-UNESCO Soil Legend |
| FAO90-FULL | yes | Full soil code of the STU from the 1990 FAO-UNESCO Soil Legend |
| FAO90-LEV1 | yes | Soil major group code of the STU from the 1990 FAO-UNESCO Soil Legend |
| FAO90-LEV2 | yes | Second level soil code of the STU from the 1990 FAO-UNESCO Soil Legend |
| IL | - | Code for the presence of an impermeable layer within the soil profile of the STU |
| PAR-MAT-DOM | yes | Code for dominant parent material of the STU |
| PAR-MAT-DOM1 | yes | Major group code for the dominant parent material of the STU |
| PAR-MAT-DOM2 | yes | Second level code for the dominant parent material of the STU |
| PAR-MAT-DOM3 | yes | Third level code for the dominant parent material of the STU |
| PAR-MAT-SEC | yes | Code for secondary parent material of the STU |
| PAR-MAT-SEC1 | yes | Major group code for the secondary parent material of the STU |
| PAR-MAT-SEC2 | yes | Second level code for the secondary parent material of the STU |
| PAR-MAT-SEC3 | yes | Third level code for the secondary parent material of the STU |
| ROO | - | Depth class of an obstacle to roots within the STU |
| SLOPE-DOM | - | Dominant slope class of the STU |
| SLOPE-SEC | - | Secondary slope class of the STU |
| TEXT-DEP-CHG | - | Depth class to a textural change of the dominant and/or secondary surface texture of the STU |
| TEXT-SRF-DOM | - | Dominant surface textural class of the STU |
| TEXT-SRF-SEC | - | Secondary surface textural class of the STU |
| TEXT-SUB-DOM | - | Dominant sub-surface textural class of the STU |
| TEXT-SUB-SEC | - | Secondary sub-surface textural class of the STU |
| USE-DOM | - | Code for dominant land use of the STU |
| USE-SEC | - | Code for secondary land use of the STU |
| WM1 | - | Code for normal presence and purpose of an existing water management system in agricultural land on more than 50% of the STU |
| WM2 | - | Code for the type of an existing water management system |
| WR | - | Dominant annual average soil water regime class of the soil profile of the STU |
| WRB-ADJ1 | yes | First soil adjective code of the STU from the World Reference Base (WRB) for Soil Resources |
| WRB-ADJ2 | yes | Second soil adjective code of the STU from the World Reference Base (WRB) for Soil Resources |
| WRB-FULL | yes | Full soil code of the STU from the World Reference Base (WRB) for Soil Resources |
| WRB-LEV1 | yes | Soil reference group code of the STU from the World Reference Base (WRB) for Soil Resources |
| WRB-SPE1 | yes | Specifier of the first soil adjective of the STU from the World Reference Base (WRB) for Soil Resources |
| WRB-SPE2 | yes | Specifier of the second soil adjective of the STU from the World Reference Base (WRB) for Soil Resources |
| ZMAX | - | Maximum elevation above sea level of the STU (in metres) |
| ZMIN | - | Minimum elevation above sea level of the STU (in metres) |
For the values of some attributes, it is indicated what is the confidence in the value. The confidence value is qualitatively expressed as high, moderate, low or very low. The confidence values for an attribute with name A are reported in an additional column with name A.CL. Also a confidence level for each STU record as a whole is provided under the attribute with name CFL.
In the above table the value "yes" in column "Confidence Level" indicates that for this attribute a confidence level is available.
Maps are views of a geographical database. In particular, soil thematic maps are views of a soil geographical database. Maps always convey only part of the information available in the database. When the structure of the database is made complex, decisions have to be taken on how to present these views. In particular, when SMUs are complex (i.e. soil associations), decisions have to be taken on what to present in views representing STU characteristics.
On this CD-ROM a large number of maps are provided which represent STU characteristics. 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 ; to understand better mapping STU characteristics, read an introduction; for definitions of "purity map" and "confidence level map", look here.
A more in-depth discussion of the database can be found in SGDBE Metadata also available as .doc file [87Kb], while SGDBE Dictionary also available as .doc file [193Kb] explains the data structures (in the Arc/Info GIS software environment) and SGDBE Attricod also available as .doc file [470Kb] provides a list of the reported attributes with their accepted values.
The Pedotransfer Rules Database (PTRDB), version 2.0
Pedotransfer rules define how to infer values for an output attribute based
on a set of values from a number of input attributes. Within the Soil Database,
the input attributes are selected among the attributes in the STU table from
the SGDBE. The whole set of pedotransfer rules constitute the PedoTransfer
Rules Database
The following list contains the new attributes for which rules have been defined.
| Attribute Name | Short description |
|---|---|
| TEXT | Dominant surface textural class (completed from dominant STU) |
| AGLIM1NNI | Dominant limitation to agricultural use (without no information) |
| AGLIM2NNI | Secondary limitation to agricultural use (without no information) |
| USE | Regrouped land use class |
| ALT | ELEVATION |
| MAT1HEV | Dominant parent material code as translated from MAT1 by Hartwich & al |
| PAR-MAT-DOM | Code for dominant parent material of the STU (inferred) |
| PAR-MAT-SEC | Code for secondary parent material of the STU (inferred) |
| OC_TOP | Topsoil organic carbon content |
| PEAT | Peat |
| PMH | Parent material hydro-geological type |
| DGH | Depth to a gleyed horizon |
| DIMP | Depth to an impermeable layer |
| HG | Hydro-geological class |
| ALT_MIN | 100 m class minimum altitudes |
| ALT_MAX | 100 m class maximum altitudes |
| ATC | Accumulated temperature class |
| DIFF | Soil profile differentiation |
| MIN | Profile mineralogy |
| MIN_TOP | Topsoil mineralogy |
| MIN_SUB | Subsoil mineralogy |
| CEC_TOP | Topsoil cation exchange capacity |
| CEC_SUB | Subsoil cation exchange capacity |
| BS_TOP | Base saturation of the topsoil |
| BS_SUB | Base saturation of the subsoil |
| DR | Depth to rock |
| VS | Volume of stones |
| TD | Rule inferred subsoil texture |
| STR_TOP | Topsoil structure |
| STR_SUB | Subsoil structure |
| PD_TOP | Topsoil packing density |
| PD_SUB | Subsoil packing density |
| AWC_TOP | Topsoil available water capacity |
| EAWC_TOP | Topsoil easily available water capacity |
| AWC_SUB | Subsoil available water capacity |
| EAWC_SUB | Subsoil easily available water capacity |
| TEXT-CRUST | Textural factor of soil crusting |
| PHYS-CHIM | Physi-chemical factor of soil crusting & erodibility |
| CRUSTING | Soil crusting class |
| TEXT-EROD | Textural factor of soil erodibility |
| ERODIBILITY | Soil erodibility class |
On this CD-ROM, there is one text file per rule (and thus inferred attribute), which describes the rule.
For a more in-depth introduction to the matter of pedotransfer rules, it is recommended to read PTRDB Metadata, also available as .doc file [102Kb].
It is worth to note that for each output attribute A, another attribute A.CL is defined which expresses the confidence level given to each inferred value.
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 the output attributes.
For in-depth implementational aspects of the database (in the Arc/Info GIS software environment), it is recommended to read PTRDB Specifications, also available as .doc file [60Kb] and PTRDB Dictionary, also available as .doc file [45Kb] which contain a synoptic overview of all the rules.
The Soil Profile Analytical Database of Europa (SPADBE)
The idea of incorporating profile data into the Soil Database was to extend the SGDBE data with quantitative data (whereas SGDBE attribute values are qualitative (e.g high, low, medium) and taken from a discrete set of predefined values). Such quantitative data should allow better modeling. Two types of profile data are provided: estimated profiles and measured profiles.
Measured profile data come from geo-located profiles taken in the field, analyzed according to own (non-harmonized) procedures in order to fill in a specific measured-profile form (Proforma I .xls file [19Kb], according to specific instructions .doc file [934Kb]); ideally these measured profiles should correspond to an STU from the SGDBE.
Estimated profile data come from profiles that should be representative for a specific STU and have been estimated by experts in order to fill in a specific estimated-profile form (Proforma II .xls file [18Kb], according to specific instructions .doc file [934Kb]). The values that had to be reported in this form were subject to a kind of harmonization.
The database includes the following analytical results for the different soil horizons :
- Texture (& particle size grades)
- Organic matter content (C, N)
- Structure
- Total nitrogen content
- pH
- ESP or SAR
- Calcium carbonate content
- Calcium sulphate content
- Electric conductivity
- CEC and exchangeable bases
- Soil water retention
- Bulk density
- Root depth
- Groundwater level
- Parent material
The result of the profile data collection and compilation are :
- A set of spreadsheet documents that hold the measured profile data (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). 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.
A more in-depth discussion of the database can be found in SPADBE Metadata, also available as .doc file [118Kb], while SPADBE Dictionary, also available as .doc file [130Kb] explains the data structures (in the Arc/Info GIS software environment) and SPADBE Attricod, also available as .doc file [340Kb] provides a list of the reported attributes with their accepted values.
Database of Hydraulic Properties of European Soils (HYPRES), version 1.0
A major obstacle to the wider application of water simulation models is the lack of easily accessible and representative soil hydraulic properties. To overcome this apparent lack of data, a project was initiated to bring together the available hydraulic data on soils, residing within different institutions in Europe, into one central database. This information has been used to derive a set of pedotransfer functions that can provide a satisfactory alternative to costly and time-consuming direct measurements.
A total of 20 institutions from 12 European countries collaborated in establishing
the database of HYdraulic PRoperties of European Soils (HYPRES). As a consequence,
it was necessary to standardise both the particle size and the hydraulic data.
Standardization of hydraulic data was achieved by fitting the Mualem-van Genuchten
model parameters to the individual 
(h)
and K(h) hydraulic properties stored in HYPRES.
The HYPRES database 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 class and continuous pedotransfer functions were developed. The class 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.
On this CD-ROM, the HYPRES Database contains only metadata, also available as .doc file [66Kb], the actual functions and function parameters, also available as .doc file [117Kb]. It does not contain the source data and results, as no agreement has been reached with the participating institutions regarding their distribution.