Soil physical parameters of a recently established agricultural recultivation site after brown coal mining in Eastern Germany

Our study deals with agricultural recultivation of open cast brown coal mining areas in Lusatia, Eastern Germany. In this region the largest brown coal (lignite) mining area of Germany is located. Lignite mining activities lead to major disturbances of the landscape. Recultivation efforts attempt to regenerate mining areas for agricultural land use options. The geological “parent” material is of saaleian origin, has a sandy texture and was excavated from several meters depths before mining and is now used for recultivating the excavated area. Consequently, it is free of recent soil organic carbon. The substrate itself is unstructured. The partly wet or dry substrate is subjected to strong mechanical stresses during the excavation, deposition, refilling and levelling processes throughout the year. This practice leads to more or less compacted soils/substrates which may result in small yields of agricultural crops. In this context we investigate the effect of different organic soil additives in combination with different recultivation crop rotations on the development of soil structure for improved agricultural land use. Our experimental site has been heaped up and levelled off in 2006 and 2007. On each of the 24 experimental sub areas undisturbed soil samples have been taken to characterise the substrates according to their mechanical and hydraulic parameters and to determine the scattering of these parameters on a site that is assumed to be recultivated as homogenously as possible. First results of our ongoing experimental study indicate that the soil physical properties such as texture, bulk density, precompression stress, air permeability and saturated hydraulic conductivity are not identical on each of the 24 subplots. The soil physical properties behave differently in relation to each other. E.g. we found a negative correlation between bulk density (∼1.35–∼1.90 g/cm3) and precompression stress (∼30–70 kPa) and no decisive interrelation between bulk density and air permeability or saturated hydraulic conductivity.