Soil properties in artificial dwelling mounds under grassland and arable land

Stopping tillage and converting arable land into grassland is often seen to be the best management practice to preserve shallow archaeological remains: It stops physical disturbance and minimizes erosion. However, pedoturbation by soil fauna, which strongly depends on the type of land use, is often neglected. Therefore land use is a key element in order to preserve archaeological remains. Plans to protect artificial dwelling mounds (“terps”) in the province of Friesland in the North of the Netherlands by converting arable land to grassland triggered a research project on the influence of land use on pedoturbation. Fieldwork was done on locations with continuous arable land and locations with continuous grassland. The research focussed on i) to which depth the soil horizons are affected by mechanical agricultural practices and soil fauna and ii) the percentage of the different soil horizons that is disturbed. As was expected soils under arable land will show a strongly homogenised plough layer, whereas the soil layers below are less disturbed. Soils under grassland are in general less homogenised but the depth to which pedoturbation occurs is deeper. The results of the fieldwork are also used in the LAPSUS model to simulate the effect of land use on the elevation profile of the artificial dwelling mounds. Especially soil translocation by tillage negatively affects the archaeological preservation. Consequently, the quantification of both tillage erosion rates and rates of pedoturbation form an important input for the land use decision making.