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

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unpublished reports, minutes of meetings and draft maps are being disregarded.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is important that at least a minimum set of such historical documents would be preserved,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.