References of "Legrain, Xavier"
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See detailSuitability of the soil map and legacy data in Wallonia (Belgium) to support the GlobalSoilMap initiative
Legrain, Xavier ULg; Bock, Laurent ULg; Colinet, Gilles ULg

in Arrouays, Dominique; McKenzie, Neil; Hempel, Jon (Eds.) et al GlobalSoilMap - Basis of the global spatial soil information system (2013, October 07)

Belgium is covered with large-scale soil map and high density of historical profiles, now available in a numerical format. This papier first gives an overview of the soil properties which can be predicted ... [more ▼]

Belgium is covered with large-scale soil map and high density of historical profiles, now available in a numerical format. This papier first gives an overview of the soil properties which can be predicted from these documents, in combination with the legacy data, and of the uncertainty we can expect for now. The great potential of the soil map is highlighted, as well as its complexity. Example of the soil depth to rock points out the need of a thorough understanding of the soil map in order (i) to interpret correctly the information hidden behind each symbols or emerging from their combination and (ii) to take into account the sub-regional features. Expert knowledge seems essential, associated with historical and new hard data, in order to build a rich and confident map which respects the recommendations of the GlobalSoilMap.net project. [less ▲]

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See detailSoil classification, map legends and GIS logic: experiences from converting the legend of the soil map of Belgium into WRB
Dondeyne, Stefaan; Legrain, Xavier ULg; Deckers, Jozef et al

Conference (2013, October 04)

A systematic soil survey of Belgium was conducted from 1948 to 1991. The purpose was to have a soil information base adequate for boosting agricultural production after the Second World War. Field surveys ... [more ▼]

A systematic soil survey of Belgium was conducted from 1948 to 1991. The purpose was to have a soil information base adequate for boosting agricultural production after the Second World War. Field surveys were done at the detailed scale of 1:5000, while the maps were published at a 1:20,000 scale. To enable soil surveyors to identify soils in the field, an original soil classification was developed based on readily observable physical and morphogenetic characteristics. Within the European Union, the World Reference Base (WRB) for Soil Resources (IUSS Working Group WRB, 2007), has been adopted as the common classification system. As soil surveys in most European countries were conducted independently, the challenge now is to convert the national legends into a common WRB legend. In Belgium, such a conversion is being implemented and we present some lessons learned in relation to classification and map legends. The legend of the soil map of Belgium is based primarily on soil texture, drainage status and profile development. “Soil series” are defined in an open and non-hierarchical structure by combining these three categorical variables, and to which modifiers can be added such as parent material, stoniness or depth to a substratum. The WRB-2007 classification is based on diagnostic features defined by morphological, physical and chemical properties. The conversion of the legend of the soil map of Belgium to WRB is based on insights gained from classifying, so far, more than 360 legacy soil profiles in combination with field observations. From these insights, heuristic rules have been deduced regrouping soil series into Reference Soil Groups (RSG) and for which some qualifiers could also be identified. Other qualifiers were determined by relying on databases of the legacy soil profiles. To take regional variability into account, the conversion is done by physiographic zone. Converting the legend of the soil map of Belgium to WRB actually leads to a regrouping of soil series into broader WRB categories and which can neatly be represented on 1:50,000 scale maps. Hence, it does not imply substituting one classification with another one. Users, who would need the detailed information, can still refer to the detailed symbols of the soil series. The regrouping of soil series has been made possible thanks to the flexibility of WRB for combining various qualifiers. However, as the WRB-2007 classification leads to a varying number of qualifiers it is less practical for constructing map legends. Therefore, the WRB-2010 guidelines (IUSS Working Group WRB, 2010) propose to organise qualifiers in main and optional ones with priority rules for the main qualifiers. As illustrated in Table 1, this approach may highlight, or hide, some qualifiers inconsistently. When for example only two qualifiers are retained in a map legend, the qualifier Endogleyic of stony, poorly drained Albic Podzols will not be indicated, while it will be indicated when such soils are not stony (Table 1). Moreover, the proposed hierarchy is sometimes also inconsistent when compared across Reference Soil Groups (RSG) as illustrated for the Arenosols and Regosols (Table 1). These drawbacks could be avoided if qualifiers would be organised into thematic groups ― such as profile development, texture, drainage, depth of substratum and fertility ― rather than by ranking them. Grouping qualifiers thematically would have the advantage to give more flexibility to the map user working with GIS, and indeed, it would render WRB a more “GIS logic” classification system. [less ▲]

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See detailProjet de Cartographie Numérique des Sols de Wallonie - Aperçu historique et missions actuelles de l'équipe de révision
Legrain, Xavier ULg; Michel, Brieuc ULg; Lejeune, Emilie et al

Conference given outside the academic context (2013)

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See detailRelationships 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
Renneson, Malorie ULg; Dufey, J.; Legrain, Xavier ULg et al

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 ▲]

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See detailCartographie du risque d’érosion hydrique à l’échelle parcellaire en soutien à la politique agricole wallonne (Belgique)
Maugnard, Alexandre; Bielders, Charles; Bock, Laurent ULg et al

in Étude et Gestion des Sols (2013), 20(2), 127-141

L’érosion hydrique des sols pose le problème de la protection de la ressource « sol » mais également de la prévention des impacts environnementaux et sociétaux qui y sont associés tels que la dégradation ... [more ▼]

L’érosion hydrique des sols pose le problème de la protection de la ressource « sol » mais également de la prévention des impacts environnementaux et sociétaux qui y sont associés tels que la dégradation de la qualité des eaux de surface, l’envasement des retenues d’eau et des bassins d’orage ou encore les inondations boueuses. Afin de cibler au mieux les mesures de lutte anti-érosives, il convient d’identifier les parcelles agricoles les plus à risque d’érosion. Mettant à profit la disponibilité d’importantes bases de données en matière de climat, sol, topographie, parcellaire et occupation du sol, une procédure automatisée de calcul de l’aléa érosion hydrique potentielle à l’échelle parcellaire, adaptée du modèle RUSLE, a été mise au point pour la Wallonie (Belgique). La carte de l’aléa érosion potentielle montre une sensibilité maximale à l’érosion hydrique en Ardenne et Haute-ardenne, en raison du relief accentué et d’une érosivité plus importante des pluies. Pour les principales zones agro-pédologiques de Wallonie, un suivi des principales cultures (céréales d’hiver, mais, betterave, pomme de terre, colza, lin) a également été réalisé, permettant d’estimer le facteur cultural C des principales successions culturales et ainsi l’érosion effective. La prise en compte de l’occupation du sol fait cette fois ressortir un aléa maximal dans les régions (sablo-)limoneuses et le Condroz, en raison des superficies importantes de grandes cultures industrielles. En Ardenne et Haute Ardenne, l’aléa d’érosion effective est faible en raison d’une couverture végétale dominée par les prairies permanentes. Enfin, sur base de la carte numériques des sols de Wallonie, une classification de la vulnérabilité des sols à l’érosion a été établie à partir du volume de sol pouvant être exploité par les racines. La vulnérabilité apparaît élevée sur une majorité du territoire wallon, à l’exception des Régions (sablo-)limoneuses et de la Région jurassique. Un indice d’érosion, calculé comme le rapport de l’érosion potentielle (aléa) sur l’érosion tolérable (vulnérabilité) permet de calculer le risque d’érosion hydrique et, par conséquent, de cibler au mieux les parcelles pour lesquelles l’érosion constitue une menace majeure pour leur valorisation durable. Une gestion appropriée de ces parcelles par un choix judicieux en termes d’occupation du sol (forêt, prairie, rotations culturales) et de pratiques culturales (p.ex., TCSL, inter-cultures) devrait permettre d’y réduire les risques de dégradation des sols par érosion hydrique. [less ▲]

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See detailProjet de Cartographie Numérique des Sols de Wallonie - Aperçu historique et missions actuelles de l'équipe de révision
Legrain, Xavier ULg; Michel, Brieuc ULg; Lejeune, Emilie et al

Conference given outside the academic context (2012)

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See detailOur soil map as cultural heritage: what of the Belgium soil survey project should be preserved and what is being lost?
Legrain, Xavier ULg; Dondeyne, Stefaan; Deckers, Jozef et al

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 ▲]

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See detailThe Belgium soil survey project: A heritage to preserve
Legrain, Xavier ULg; Dondeyne, Stefaan; Deckers, Jozef et al

Conference (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 ▲]

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See detailConverting 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
Bouhon, Antoine; Dondeyne, Stefaan; Legrain, Xavier ULg et al

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 ▲]

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See detailConverting the legend of the Soil Map of Belgium into the World Reference Base for Soil Resources: Strenght and constraints of using WRB as a map legend
Dondeyne, Stefaan; Bouhon, Antoine; Legrain, Xavier ULg et al

Conference (2012, July 03)

Within the European Union, there is a general interest to prepare joint soil maps at a 1:250000 scale in order to harmonise agricultural and environmental policies. The World Reference Base for Soil ... [more ▼]

Within the European Union, there is a general interest to prepare joint soil maps at a 1:250000 scale in order to harmonise agricultural and environmental policies. The World Reference Base for Soil Resources (WRB) has been adopted as the common soil classification system within the EU. As soil surveys in most member states were conducted independently, the challenge is now to convert the national legends into a common WRB legend. Based on our experiences from converting the legend of the Soil Map of Belgium to WRB, we discuss the strengths and constraints of using WRB for both large scale (1:50000) and small scale (1:250000) maps. By using WRB Reference Soil Groups with one or two main qualifiers, the principal soil information of the original 1:20000 scale Soil Map of Belgium can be represented. Inevitably the conversion to WRB leads to some loss of information as details on soil texture, drainage and substratum get generalised into broader categories in WRB. This generalisation however can be neatly presented on 1:50000 scale maps. Being less complex than the original maps, these maps have the advantage to provide better insights into the regional soil geography. Moreover, as they are built on international classification concepts, the historical soil maps are made accessible to a wider audience. The conversion into WRB units also allowed for a straightforward generalisation and production of small scale maps (1:250000) which should be suitable for producing a soil map at European level. [less ▲]

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