Les sentiers géo-pédologiques en Province de Namur - Patrimoine géologique et pédologique en Province de Namur - 500 millions d'années de façonnement de notre paysage - Itinéraire de Freyr

Learning material (2013)

Relationships between the P status of surface and deep horizons of agricultural soils under various cropping systems and for different soil types: a case study in Belgium

in Soil Use and Management (2013), 29(S1), 103--113

Application of phosphorus (P) fertilizers to agricultural soils should be based on sound knowledge about soil P reserves, availability and lability to optimize conditions for plant uptake while limiting P ... [more ▼]

Application of phosphorus (P) fertilizers to agricultural soils should be based on sound knowledge about soil P reserves, availability and lability to optimize conditions for plant uptake while limiting P transport to surface waters. This study investigated relationships between parent material (PM), land use and P fractions in agricultural soils at a regional scale. Surface and deep (100–120 cm) soil samples were collected from 120 agricultural sites (240 total samples) and analysed for three P forms (inorganic, organic and available) as well as for additional key properties. Land uses within the study area were continuous cropland, permanent pasture and temporary grassland. The area covered the 12 most common parent types in Wallonia. Mean total P contents were 904 and 401 mg/kg in surface and deep samples, respectively, with a 33% coefficient of variation for both horizons. The organic P fraction represented, on average, 30% of total P, while available P corresponded to 9% of total P. The influence of PM was apparent in both the surface and deep soil samples, while land use influenced only surface properties. The pattern in total P content relative to land use was pasture ≥ cropland ≥ temporary grassland. Correlation analyses highlighted significant relationships between edaphic parameters viz Alox, Feox, CEC, TOC, pH and P content, the main soil parameter being Alox which determines P sorption capacity. An enrichment factor was used to distinguish between geogenic sources and human activities in terms of topsoil P content. [less ▲]

Mapping of the occurrence of phreatic groundwater or karst-sensitive rocks at less than one meter depth in Wallonia, based on the interpretation of the Digital Soil Map of Wallonia

Report (2013)

Projet de Cartographie Numérique des Sols de Wallonie - Aperçu historique et missions actuelles de l'équipe de révision

Conference given outside the academic context (2012)

Our soil map as cultural heritage: what of the Belgium soil survey project should be preserved and what is being lost?

Poster (2012, July 06)

Between 1947 and 1991, soils of Belgium were mapped to establish a systematic inventory of the country soil resources. Field observations were done by soil auger to a standard depth of 1.25 m and at a ... [more ▼]

Between 1947 and 1991, soils of Belgium were mapped to establish a systematic inventory of the country soil resources. Field observations were done by soil auger to a standard depth of 1.25 m and at a mean density of 2 points per hectare. Cadastral plans at scale 1:5,000 where used for georeferencing field observations and for delimiting map units, subsequently generalized on the 1:10,000 topographic base map. The final map was published on sheets at scale 1:20,000 along with descriptive texts. Besides, data on about 15,000 described and analyzed soil profiles were reported in technical annexes. With the advent of computers, data on soil profiles have been transfered into relational databases and soil sheets have been digitized. Coding of the data rendered them more accessible, but inevitably implied a standardization and hence a reduction of some information. Still most of the soil surveyors have already passed away, besides their intangible expert knowledge, a wealth of information is also being lost when their field notes, unpublished reports, minutes of meetings and draft maps are being disregarded. The map legend was developed during the first decade of the survey, reflecting state of knowledge on soil formation and their relative importance for agricultural land-use in the 1950s. To guarantee that future generations will be able to appreciate the value and concepts underpinning the soil information, it is important that at least a minimum set of such historical documents would be preserved, analyzed and documented. [less ▲]

Converting the legend of the Soil Map of Belgium into the World Reference Base for Soil Resources: Lessons from correlating national soil survey data to an international soil classification system

Poster (2012, July 03)

Soils in Belgium were mapped between 1947 and 1991 and published at a 1:20000 scale. These maps are used in land consolidation projects and for assessing soils’ vulnerability to erosion and pollution ... [more ▼]

Soils in Belgium were mapped between 1947 and 1991 and published at a 1:20000 scale. These maps are used in land consolidation projects and for assessing soils’ vulnerability to erosion and pollution. Integration of land-use and environmental policies within the European Union however requires a harmonization of different national soil classification systems. With the World Reference Base for Soil Resources (WRB) as common classification system within the Union, the authorities of Flanders and Wallonia commissioned a study to elaborate a methodology for converting the Belgian soil legend into WRB. The Belgian legend is based on field properties such as texture, drainage status and profile development. The WRB classification is based on diagnostic features defined by morphological, physical and chemical properties. A key and software programme have been developed to convert the Belgian units into WRB units. However, as many Belgian units could not unequivocally be translated into WRB units, additional guidelines had to be derived based on soil survey data classified according to WRB. The data show that principles of the legend shifted over time or were interpreted differently to take regional specificities into account. To overcome resulting ambiguities it is proposed to establish a database of reference soil profiles. Whereas, overall WRB is satisfactory for classifying soils at national level, the experience also shows that some WRB concepts may benefit from revisions to facilitate its correlation with national soil survey data. [less ▲]

La Carte des Sols de la Belgique, outil d'estimation de la pression urbanistique sur les sols

Conference (2012, March 20)

Ces dernières décennies, des pressions de tout ordre ont induit une forte expansion de l’urbanisation en Europe, à laquelle la Belgique n’échappe pas. L’imperméabilisation des sols a par ailleurs été ... [more ▼]

Ces dernières décennies, des pressions de tout ordre ont induit une forte expansion de l’urbanisation en Europe, à laquelle la Belgique n’échappe pas. L’imperméabilisation des sols a par ailleurs été identifiée comme une des principales menaces pesant sur eux. Au-delà du constat de l’évolution des surfaces artificialisées en Wallonie, l’objectif de cette étude est d’identifier les sols les plus soumis à ce phénomène. L’élaboration de la Carte Numérique des Sols de Wallonie (CNSW) – à partir d’un document historique, la Carte des Sols de la Belgique levée à grande échelle entre 1947 et 1991 – et de la Carte Numérique d’Occupation des Sols de Wallonie ouvre des perspectives intéressantes à ce sujet. Plus spécifiquement, l’utilisation de cartes d’aptitude des sols pour l’agriculture, dérivées de la CNSW, met en évidence l’impact de l’artificialisation sur la réserve en sols de meilleure potentialité agricole (figure 1). Cette dernière a diminué de 5 % à l’échelle de la Wallonie suite à l’artificialisation des sols ces 60 dernières années. La réalité est plus contrastée à l’échelle locale. La moitié des 262 communes wallonnes se situe en deçà, tandis que d’autres ont perdu (du point de vue agricole) jusqu’à 50 % de leurs meilleurs sols, par ailleurs initialement fortement présents sur leur territoire. Autre constat : si la moitié des communes subit une artificialisation uniforme de ses sols, 20 % d’entre elles voient leurs meilleurs sols préférentiellement artificialisés par rapport à ceux de potentialité agricole moindre.Une analyse spatiale fine à plus grande échelle (figure 2) ouvre la voie à la compréhension des phénomènes en jeu et in fine à l’élaboration de recommandations face à la concurrence inévitable entre deux fonctions essentielles des sols : la production agricole et le support des activités humaines. [less ▲]

Saving our soil information, making our soil map more understandable, usable and useful in the digital era: contribution of the Digital Soil Map of Wallonia Project

Scientific conference (2011, December 07)

Due to greater awareness of the necessity to preserve soil functions from human pressure on the environment, the need for soil information is increasing. Supported by the evolution of technologies these ... [more ▼]

Due to greater awareness of the necessity to preserve soil functions from human pressure on the environment, the need for soil information is increasing. Supported by the evolution of technologies these last decades, great efforts were achieved to provide up-to-date, high resolution, continuous data on soil properties. These efforts are valuable and necessary, but they are often restricted to limited surfaces. Morevover, each of these data reveals partial picture of the soil and doesn’t give an insight into their genesis, organisation and functionality. Therefore the Soil Map of Belgium remains an essential resource. On the other hand, foreign (soil) scientists frequently claim that we (the Belgium country) have a prodigious soil map and implicitly conclude we don’t need any more soil information. More questionable, many users of the now available digital soil maps think they obtained the « Holy Grail » allowing them to extract all the information they need about soil. This is clearly not the case, many currently « wanted » soil parameters being either missing, or displaying insufficient precision. But the wealthy potential of the Soil Map of Belgium in itself is not enough nor always advisedly used. Here are some of the multiple reasons to underline: (i) the map and its legend are complex and few people take/have time to (properly) learn it before use ; (ii) the great number of legend units is confusing for users, lacking tools for organising and stratifying their data ; (iii) the easygoing use (from a GIS point of view) of the legend units, due to their concatenated structure and facilitated by the split structure of the digital map’s attribute table, leads incidiously to a clearcut « symbol by symbol » use of the map, coupled with strict definition of the symbols. Hence a sharp loss of information and comprehension emerging from the whole legend unit or linked to the interpretation of the symbols ; (iv) without the undeniable expert knowledge of the generation who made the map, the current users don’t have in mind the regional nuance, the numerous implicit information lying into the legend, the concepts used during the survey and reflecting state of knowledge on soil formation and their relative importance for agricultural land-use in the 1950s ; (v) the new generation is desperatly short of practice of soil observation in the field ; (vi) a wealth of information is also being lost when the field notes, unpublished reports, minutes of meetings and draft maps are being disregarded, as well as other legacy data associated with the map (booklets, monographs, …). This presentation will show through selected examples how the Digital Soil Map of Wallonia Project contribute to overcome this situation in order to reach this ambitious but feasible objective : a better understanding and use of the Soil Map of Belgium by the maximum of people. [less ▲]

Révision de la Carte Numérique des Sols de Wallonie - Campagne de recherche 2011-2012 - Premier rapport intermédiaire

Report (2011)

Production de cartes généralisées à partir de la Carte Numérique des Sols de Wallonie

Poster (2011, July 07)

La Belgique est parmi les premiers et rares pays à s’être dotée, entre 1947 et 1991, d’une carte des sols à grande échelle (1/20 000) sur l’ensemble de son territoire. Entretemps, le développement actuel ... [more ▼]

La Belgique est parmi les premiers et rares pays à s’être dotée, entre 1947 et 1991, d’une carte des sols à grande échelle (1/20 000) sur l’ensemble de son territoire. Entretemps, le développement actuel des applications numériques d’une part, une prise de conscience accrue de l’importance de préserver les sols d’autre part, ont amené la Région wallonne à entreprendre la digitalisation de la partie wallonne de la Carte des Sols de la Belgique, pour aboutir à la production d’une couche numérique cohérente sur l’ensemble du territoire wallon, accompagnée d’une légende unique et exhaustive : la Carte Numérique des Sols de Wallonie (CNSW). Sa très grande précision, tant spatiale que sémantique, en fait un outil d’analyse puissant, mais également particulièrement complexe à manipuler. Partant du constat qu’une grande partie du territoire peut être couverte à partir d’un nombre limité d’unités cartographiques parmi les 6 000 existantes dans la CNSW, une carte des Principaux Types de Sols de Wallonie à l’échelle du 1/250 000 en a été dérivée, offrant ainsi une vision d’ensemble et une perspective d’intégration européenne. La légende fut conçue à partir de regroupements logiques des sols sur base de trois des quatre critères majeurs des unités cartographiques de la CNSW, à savoir la texture, le drainage naturel et la nature de la charge caillouteuse lorsqu’elle est présente. Adoptant des principes de dominance par l’utilisation des termes « principalement » ou « quasi-exclusivement », elle ne peut néanmoins être qualifiée de carte d’associations de sols du fait des restrictions de regroupement adoptées. Outre le rattachement de chaque plage cartographique à une des classes ainsi définies, un processus de généralisation cartographique a été effectué dans le but d’une meilleure lisibilité à l’échelle du 1/250 000. Cette carte fut utilisée comme support à la sectorisation du territoire wallon en 24 Districts de l’Espace Rural, sur base d’une analyse à caractère géomorphopédologique. Ces Districts sont à leur tour utilisés pour la réalisation de cartes des Principaux Types de Sols à l’échelle du 1/100 000, sur le même principe que la carte à l’échelle du 1/250 000. Ces diverses cartes généralisées permettent d’envisager la confrontation de la CNSW avec plusieurs gisements de données d’analyse disponibles, selon différentes échelles. En tant qu’outil d’intégration, de structuration et de cadrage de l’information pédologique, elles doivent devenir de plus en plus le fondement de Systèmes Régionaux d’Information sur les Sols et leurs propriétés. [less ▲]