FG Bodenschutz und Rekultivierung
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Recultivation efforts in mining areas attempt to regenerate soils and landscapes for various land use options and create initial conditions which are beneficial for the development of the future ecosystems. On very young landforms physical and chemical properties of soils play a major role for the further evolution of the developing ecosystem as well as the landforms itself. Less is known about the very first alterations of physical parameters in accordance to different land uses and recultivation practices. Our study deals with the agricultural recultivation of post lignite mining areas in Lusatia, East Germany. The sandy substrate used for recultivation stems from depths of several meters and is therefore free of recent soil organic matter. The substrate itself is unstructured. After it has been excavated and transported on conveyor belts to the recultivation site, it is piled up to dams of a height of 1-4 m and levelled off with heavy crawlers. During these processes the substrate is subjected to strong mechanical stresses. This practice induces compaction which causes decreasing yields of agricultural crops to a certain extent. In this context we are investigating 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 recently been heaped up and levelled off. On the 25 experimental sub areas 2175 undisturbed soil samples were taken out of three soil depths to characterize initial physical properties before any recultivation measures have been applied,. We present laboratory results of this status-quo sampling. The results indicate that the site is very heterogeneous in terms of mechanical stability, bulk density, total pore volume, saturated hydraulic conductivity and air permeability. Moreover, our results show that bulk density is not an appropriate parameter to derive soil functions, e.g. permeability or stability. Additionally we found that even in areas of bulk densities > 1.8 g/cm3 and with an inclination < 2 % impressive run-off and gully erosion developed during heavy rainfall events. We conclude that initial processes altering soil physical parameters play a major role for the landform evolution within the first 12 months after dumping. Further studies should reveal the mid-term impact of organic additives on the soils after 7 yrs.
Grazing-induced alterations of soil hydraulic properties and functions in Inner Mongolia, PR China
(2009)
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.