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

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.