Physical soil properties in specific fields of application especially in anthropogenic soils

The knowledge about the physics of soil properties is important for the understanding of the processes, which take place in a considered (elementary) soil volume and which have an impact on the environment. Soils, which have developed during centuries and milleniums respectively, are formed by processes, which created a relatively uniform structure and which can be described by known physical properties. However, the physical description is complicated or even impossible, when the mathematical definition cannot be extended linearly due to the problem of the combination of e.g. different scales. This problem is even magnified, when anthropogenic soils have to be described. Man made soils comprise in this sense soils, which range from extremely heterogenous in texture and structure (urban soils) to very uniform (e.g., highly compacted soil material, which is used for sealing purposes in respect to hydraulic and chemical flux). The soils show on the one hand a very high spatial variability with the problem to include the single 'homogeneous' elementary compartments and their properties, which can differ to a great extent, into linear physical theories. On the other hand known physical formulations of the processes are no longer valid, because the boundary conditions of the theoretical approach are beyond their validity (e.g. water flow and Darcy law in highly compacted and very loose soils respectively). Furthermore, anthropogenic soils underlie a rapid development due to high gradients in physico-chemical processes. Therefore methods have to be considered and developed, which allow the description of soil properties. As an outcome schemes of the design for sampling soil cores are the basis for measurements of the spatial heterogeneity and the comparison of field and laboratory data. However many of the problems which try to describe soil physical properties cannot be solved with existing models. This paper wants therefore to describe approaches, which allow the definition of the processes and hence the description of soil physical properties. The derivation of new concepts are important to have a mean for the modelling of processes, e.g. water flow, affecting the environment. (C) 1998 Elsevier Science B.V. All rights reserved.