A long-term hydrological soil study on the effects of soil and land use on deep seepage dynamics in northeast Germany

Abstract

Starting in 1993, interactions between land use and precipitation have been investigated in three research areas of northeast Germany. The research based on continuous measurements of soil water tension and water content down to a depth of 5 m at 36 plots situated at diverse soils under different land use (arable land, forest, grass fallow). At arable sites, the main period of deep seepage occurred between February and April during the study period. With 175 mm a⁻¹, the mean annual deep seepage rate under arable land was highest at sandy soils. At loamy soils, the mean seepage rate amounting to 122 mm a⁻¹ appeared significantly less. Smallest seepage rates, however, were determined for forested plots (pine 15 mm a⁻¹, beech 18 mm a⁻¹). Differences were significant as compared to arable land at sandy and loamy soils and grass fallow. It is concluded that deep seepage and groundwater recharge under forest will tend to wane at annual precipitation rates of <550 mm a⁻¹. This should be taken into account in decision making on land use planning and conversion of arable areas to forestry in regions characterised by negative values of the climatic water balance.

Keywords:

• land use
• soil hydrology
• soil water tension
• soil water dynamics
• deep seepage