Een gedetailleerde bodemkartering van de gemeente Didam

The soil survey was to obtain data on the community of Didam, because of agricultural, economic and social problems (many smallholders) and to find the possibility of extending horticulture. Other studies were of pleistocene cover sands and holocene geology, soil formation, vegetational and occupational history since palaeolithic times.The soil map consists of physiographic units, an old reclamation sand landscape, a recent reclamation landscape and a river-clay landscape. Each of these soil landscapes was classified into soil series and types, based on thickness of topsoil, depth of gleying and mechanical composition, all of direct value for agriculture. The old reclaimed sand landscape was, for example, classified into old arable sand soils (plaggen soils) and old grassland soils (Humic Gleysoils). Some trial samples were taken to compare the productivity of the soil types. It was concluded that agricultural crops showed more pronounced differences than grassland, because also management played an important part. Horticulture might be improved by taking advantage of natural circumstances (soil, water control).A remarkable fact, studied in this area, was the deposit of iron ochre in many subsoils, caused by seepage water from the hills of Montferland. It consisted chiefly of goethite (α-FeOOH) and affected growth of crops.