Due to several hundred years of Plaggen agriculture in the Oberesch area, archaeologists are facing special soil conditions here. Since the Middle Ages, local farmers have cut out pieces of sod to use them as bedding in their stables. Later on, these sod pieces called Plaggen, now saturated with manure, were put on fields as fertilizer. In this way, an up to one meter thick layer of Plaggen soil built up in Kalkriese over time. In various locations, the historical state of the surface has been preserved beneath this layer.
The 2,000-year-old soil conditions of the Kalkriese site were researched by soil scientists from the University of Oldenburg (Lower Saxony), who were able to partially reconstruct the state of the Oberesch’s relief in Augustean time based on soil surveys and core samples. The earth’s surface was much more diverse and irregularly shaped in that period. Currently, soil scientists from the University of Osnabrück and from Hochschule Osnabrück are investigating in which period soil erosion occurred on the Kalkriese Hill and how these layers can be distinguished from Plaggen soil.
In the past few years, soil scientists also tried to locate archaeological evidence underneath the Esch prior to excavations with the aid of magnetic prospection. For many years, this method has been applied very successfully in the search for archaeological sites in regions without Esch layers. Magnetic scans allow researchers to identify pits, ditches or wall fragments, so that settlement structures or burial sites can be found without excavations. However, in the Kalkriese region scientists soon learned that the Esch significantly impairs the use of this natural scientific method. Without excavations, substantial knowledge of archaeological findings can hardly be obtained here.