http://www.pressesagro.be/base/ Publisher: Les Presses agronomiques de Gembloux, ISSN 1370-6233, eISSN 1780-4507. fr-be http://www.pressesagro.be/picture/cover/issn/small/13706233.jpg http://www.pressesagro.be/base/text/v15ns2/643.pdf By Colinet G. / Foreword. /. http://www.pressesagro.be/base/text/v15ns2/647.pdf By Legrain X., Demarcin P., Colinet G., Bock L. / Soil mapping in Belgium: historical overview and presentation of the current work on valorisation and revision of the Digital Soil Map of Wallonia. Over the past few years, there has been growing concern about soils and their properties, thanks to greater environmental awareness. Consequently, existing documents on soil are valuable in risk assessment and for the research of well-adapted solutions. In this context, this paper reviews the main stages of soil mapping in Belgium and presents current works to valorize the Digital Soil Map of Wallonia and update associated databases. Belgium is among the first countries to be completely covered by a detailed soil map (1:20,000). The origin of the Soil Map of Belgium, its realisation between 1947 and 1991, the principles and characteristics as well as the related products are described. But since its publication, due to the increasing need of soil information and thanks to the development of geographical information systems the Walloon part of the map was digitalised between 2000 and 2003 by the Digital Soil Map of Wallonia (DSMW) Project. From this early action at regional level, a selection of immediately derived products is presented and briefly commented. However, if these products go beyond the initial objective of agricultural production increase, they do not always meet the environmental challenges nor the future legislation at European, national and regional levels. To fill this gap, the recent tasks carried out by the DMSW team are presented through a description of their methodological and technical framework. The long-term objective is to build Regional Soil Information Systems based on the use of the Digital Soil Map of Wallonia as a tool of integration, structuring and referencing of pedological information. http://www.pressesagro.be/base/text/v15ns2/657.pdf By Genot V., Buffet D., Legrain X., Goffaux M.J., Cugnon T., Oger R., Bock L., Colinet G. / To a sampling and personal fertility advice, the tools for decision support. Environmental and agronomic issues require always more well thought and suited farmer management of agricultural inputs; soil analysis is therefore an essential tool to support decision. However, for a soil analysis to provide valuable information, it is essential for the sample to be representative of the studied field. Without this representativeness, an analytical result, as accurate as it could be, would not be of interest if it could mislead the farmer. In practice, the main difficulty for the sampler is the recognition of soil criteria which are essential to provide a fertility advice, especially in Wallonia (Belgium) where soil variability is very important. With the Digital Soil Map of Wallonia (DSMW), drowned at the scale 1/5,000, it seems appropriate to give these information to the samplers in an useful form for routine works. That is why a mapping tool for decision support, named REQUACARTO, was designed to be used for soil analysis by provincial laboratories, members of the REQUASUD laboratories network. This tool responds to a real requirement in Wallonia: achieving a quality sampling for the development of personalized soil fertility advice. http://www.pressesagro.be/base/text/v15ns2/669.pdf By Liénard A., Bock L., Colinet G. / Interest of soil maps to elaborate a sampling strategy in soils contaminated by atmospheric fallouts: application to the study of soil effect on the fate of metallic trace elements. As a result of pollution from atmospheric dusts, some sites of Wallonia (Belgium) are contaminated by metallic trace elements (MTE) such as cadmium, lead and zinc. These metalliferous soils are called 'calaminary sites'. The major aim of this study concerns the multi-scalar characterization of MTE distribution in these contaminated soils and landscapes. The strategy of sampling described in this paper is based on the influence of soil type and its land use on the fate of MTE. After analysis of collected samples, it will be possible to have an idea of the distribution of MTE among soil components, and therefore, to evaluate the risks caused by environmental changes such as an agricultural use of afforested areas. http://www.pressesagro.be/base/text/v15ns2/683.pdf By Legrain X., Renneson M., Genot V., Demarcin P., Liénard A., Bock L., Colinet G. / A methodology for site selection and soil sampling in relation with main parent materials in Wallonia (Southern Belgium). Despite the small size of its territory, Wallonia shows a geological context singularly varied and contrasted. From main geostructures to lithostratigraphical formations, this diversity has greatly influenced soil types. Rock weathering represents one of the main processes in soil forming. Throughout its nature and its composition, the parent material is identified as one of the main factor influencing pedogenesis and soil properties. Understanding the spatial determinism of these properties requires a better characterisation of the parent materials as well as of their spatial distribution. The Soil Science Unit of Gembloux Agro-Bio Tech has therefore initiated the collect of topsoil and subsoil samples representative of the diversity of Walloon agricultural soils, in relation with their parent materials and presenting a wide range of physico-chemical properties. The sampling strategy relies on the stratification of the territory in physical units and on the identification of the dominant parent materials and soils. The 1:20,000 Numerical Soil Map of Wallonia, the 1:250,000 Map of the Main Soil Types of Wallonia and the Map of Rural Space Units helped largely to fulfill these tasks. The very wide panel of feasible analyses on these samples opens interesting prospects on valorization of the data in a regional soil information system. Indeed, considering the importance of samples representativity in the approach, the pedotheque and analytical database should become reference tools in Wallonia, serving needs of numerous research projects. http://www.pressesagro.be/base/text/v15ns2/699.pdf By Degré A., Sohier C., Colard F., Kummert N., Bauwens A., Rauw J., Beckers E. / Hydrology: a partner of geomorphopedology in the scope of a scale-through environmental management. Unsaturated soil and subsoil are often called "critical zone" considering their major interfacing role in our environment. Dealing with solute transfer or water and soil conservation, hydrologic research relies on pedologic descriptions. It is the case from micro to macro scale analysis. Hydrodynamic parameters are derived from pedologic information on soil. They allow hydrologists to quantify and spatially describe the dynamic exchanges between water, soil, crops and atmosphere. The modelling of water and solute transfer through soil and vadose zone also needs them. The paper presents some research highlights on soil behaviour, hydrological modelling and forecasting under climate change. Erosion is another major topic. Soil is a poorly renewable resource. Soil conservation and soft hydraulic management in watersheds deserve more attention. They can help limiting nutrient and sediment transfer to surface water. Again, pedologic information is the starting point of conceptualization and modelling. Furthermore, the Soil Map of Belgium includes information on geomorphology and landscape descriptions which date from decades. They are of first importance to calibrate and validate detachment, transport and sedimentation models. In the current context of high environmental concern, it is demonstrated how hydrology and pedology have to be partners in order to deal with such major issues. http://www.pressesagro.be/base/text/v15ns2/709.pdf By Bah B.B., Vanclooster M., Oger R., Bock L., Colinet G. / Making use of the Digital Soil Map of Wallonia and of an available soil analysis database for assessing the risk of pesticide leaching to groundwater. This study shows how the Digital Soil Map of Wallonia and the associated soil database Aardewerk can be combined with the MetaPEARL model to assess the sensitivity of agricultural soils to pesticide transfer into underground water tables in Wallonia (Southern Belgium). MetaPEARL is based on an analytical expression which describes the concentration of leached pesticides at the soil profile bottom depending on available data on soil characteristics, climate and pesticide properties. The results show an important soil sensitivity to pesticide transfer with a coefficient of retention on organic matter (Kom) very weak (about 10 dm3.kg-1) or with a relatively high half-life time (DT50 about 60 days). In this case, the pesticide is weakly retained by soil organic matter or slowly degraded and then stays available in the soil and can be quickly leached during rainfalls. In other respects, the pesticide sensitivity to leaching is strongly correlated with soil texture and its organic matter content. It is also observed that the concentration of leached pesticide is strongly depending of the rainfall surplus (water flux into the soil or hydrous balance). A sensitivity analysis has shown that the model is very sensitive to soil thickness, to organic matter content, to the bulk density of the mineral fraction by textural classes and of the organic matter. Therefore, these pedological variables have to be assessed with the highest precision to avoid adding further uncertainty to the predictions obtained. On the basis of the most sensitive soil variables, the analysis of "spatial" uncertainty related to the results delivered by MetaPEARL, due to the consideration of an unique representative value by soil type and by region (deterministic approach), shows that this approach tends to under-estimate the concentration of pesticide leached in the soil, compared to the use of a stochastic simulation (probabilistic approach) which takes into account the soil characteristic variability within a given soil type. This stochastic approach allows also the calculation of a more relevant threshold of risk probability (percentile) which can be compared to an imposed standard in view to enhance a sustainable management of natural resources. http://www.pressesagro.be/base/text/v15ns2/727.pdf By Ridremont F., Lejeune P., Claessens H. / Pragmatic assessment of the water reserve of the forest sites and mapping at the regional scale (Wallonia, Belgium). The assessment of the forest sites water availability constitutes a growing concern following the awareness of the potential impact of climate change on the soil moisture regime. At the present time, the forest managers lack tools for a quantitative estimation of the soil water reserve. This paper presents a simple estimation method that can be adopted on field by foresters. A map of this soil water reserve at the forest site scale has been established for the Southern Belgium. After the inventory of the possible techniques, the "textural method", based on the pedotransfert classes of Jamagne et al. (1977), has been used. The soil profiles from the Aardewerk database have eased the translation of the Jamagne et al. (1977)'s results in the Belgian textural system. Moreover, the geodatabase of the Digital Soil Map of Wallonia (DSMW), through the typology of the major soil types, has been used as mapping support of the water reserve at the regional scale. Like a first attempt of validation, the result has been compared with the bioindicator character of forest understory vegetation. The regression results show a significant relationship between the soil water reserve and the vegetation estimate, but they also indicate that the water reserve does not explain alone the moisture level expressed by the flora. It emerges that the characterization of the Walloon parent materials will constitute an undeniable support for the development of the proposed method, the transposition of foreign results leading to some bias. The use prospects of this thematic map are multiple: integration as inputs for the autecological modelling, assessment of the moisture regime for the water availability of forest sites and building of sites catalogs; as many tools to guide forest managers in their planning measures. http://www.pressesagro.be/base/text/v15ns2/743.pdf By Bouhon A., Brahy V., Engels P., Chapelle J. / WalRB project: translation of the legend of the soil map of Belgium into World Reference Base for Soil Resources (WRB). Soil maps are among the most important reference maps in environmental and agriculture fields. Determination of land, agricultural potential, erosion thread, land management or soil pollution are some topics that need spatial soil data. Attention to cross-border environmental matters, such as soil protection, has become an international concern that requires harmonized soil information. This is why the World Reference Base for Soil Resources has been selected by European Union as official soil classification system (IUSS Working Group WRB, 2007). Belgium is one of the first nations to have achieved the whole country soil survey at large scale (1:20,000). The legend of the soil map of Belgium is based on three or four main soil specifications, texture, drainage class, profile development and stoniness nature (for stony soil), each one represented by a letter. Those three or four letters all together form the main soil series. Prefix and suffix may be added to further detail it. The WRB system based on soil morphology is formed of two levels, 32 Reference Soil Groups (RSGs), and various qualifiers (prefix, suffix or both). A common methodology between Flanders, Luxembourg and Wallonia (that use the same soil map legend) is requested to carry out the translation. Data from different databases, digital soil maps, soil profile descriptions, soil analytical data, Digital Elevation Model, other thematic maps (e.g. flooding hazard areas) are collected and organized under a common PostgreSQL database [Belgian Soil Profile Database (BSP)], with PostGIS geographical extension, hosted under a dedicated server. Data validation is proposed to be done under the auspices of National Soil Committee of Royal Academy for Sciences and Arts of Belgium. Algorithms are implemented in Perl and R languages.