Agriculture Reference
In-Depth Information
published in 1966 (Dupuis, 1966). This was subsequently greatly supplemented by other studies
so as to be integrated into the European Community soil map (EEC, 1985; 1986). These additions
were carried out using the work of the ÑSoil Survey Staff of FranceÒ (SESCPF) of INRA for the
drawing up of soil maps at 1/100,000, a program which is still underway (INRA-SESCPF,
1969Ï2001). The European program ÑGeographical Soil Database of EuropeÒ subsequently har-
monized and structured the whole of the collected information in the information system EUSIS:
European Soil Information System (EU-JRC, 2001).
The French Soil Database contains, at an accuracy of 1/1 M, 917 STUs regrouped in 318 SMUs
(Jamagne et al., 1995). These STUs belong mostly to the following Reference Soil Groups of the
WRB (FAO-ISRIC, 1998):
Histosols, Anthrosols, Leptosols, Vertisols, Fluvisols, Gleysols, Ando-
sols, Podzols, Planosols, Calcisols, Albeluvisols, Luvisols, Umbrisols, Cambisols, Arenosols, Rego-
sols
, and to the following Orders of Soil Taxonomy (Soil Survey Staff, 1999):
AlÝsols, Andisols,
Entisols, Histosols, Inceptisols, Mollisols, Spodosols, Ultisols, Vertisols.
There are a great number of soils in the French territory, and we can see quite easily the major
fundamental pedogenetic processes that control the evolution of the surface formations of this
territory. These dominant processes are essentially ÑbruniÝcationÒ (weathering without important
transfer of matter within the pedon) and leaching, and, to a lesser degree, podzolization. However,
when a dominant factor, such as signiÝcant calcium content or excess water, intervenes in the
genesis, other types of evolution can occur. Among the different genetic factors that have a great
signiÝcance in the evolution of French soils are, Ýrst, the
geolithological context
, then the
geomor-
phological context
, and lastly the
climatic and paleoclimatic inÞuences.
Different types of Soil-systems have been deÝned, cartographically delimited, and described in
the course of the many works of cartographic inventory (INRA, 1969Ï2001), and are made up of
groups of pedons or STUs linked among each other by functional processes. It is sometimes difÝcult
to select soil systems that are sufÝciently representative of large areas, and some rules had to be
followed (Bui et al., 1999). The Soilscapes in question are essentially deÝned by the nature of the
parent material and by a certain number of topographic criteria enabling the deÝnition of these
types of relief, that is to say, the ÑlandformsÒ (FAO, 1995), as well as by the different soils distributed
on the slopes. A Ýrst framework for a typology of the French soil-systems could therefore be based
on these parameters.
The
information is provided, for areas mapped at scales ranging between 1/10,000
and 1/250,000, by the dominant parent material identiÝed during the surveys at the level of the
map units.
lithological
are of fundamental importance, and the information
has, until recently, been obtained by simple analysis of topographic levels contours and specialistsÔ
descriptions. The Digital Elevation Models (DEMs) now enable higher precision in this domain,
as well as the possibilities of quantiÝcation. From DEMs, it is possible to locate and delimit
catchments or watershed areas of varying surfaces (IRD-ORSTOM, 1995). Independently of the
numerous results obtained with reduced resolutions, 10 m to 30 m, we have been able to test the
relevance of DEM at much larger grids: 250 m for the territory of France and 1000 m for Europe.
Our current approach, which is to attempt a typology of the principal soilscapes represented in the
French territory, will be illustrated with three concrete examples of toposequences that are Soil-systems.
Geomorphology
and
topography
Examples of Soil-systems in France
These examples come from three representative areas that are geomorphologically and litho-
logically different, including the following:
¤a hilly loessic region in the Paris Basin
¤a region of depression on a detritic cover in the Central Region
¤a medium mountainous region in the Massif Vosgien
The distribution of the main soil types of the three regions are brieÞy discussed.
