Introduction

Abstract

A decisive portion of many of the cycles of energy and matter in our natural environment passes through the soil. To possess knowledge of what happens in soils, formerly nearly exclusively an attribute of farmers and foresters, is today indispensable for everyone who is interested in the interactions between human life and the environment, or who has to intervene actively in environmental cycles in the frame of his duties. To carry out measures which are supposed to have a positive effect on the environment without knowledge on the dynamics of water in and below the rootzone can be compared to the operation of mines without the knowledge of geology. For the water balance and for the air balance in the soil, for the movement of soil solutes, for soil formation, for soil erosion, as well as for many other processes in the soil, the morphological properties of the upper decimeters of the soil cover are of special relevance. For just this zone, however, important laws of classical soil physics, with which one tries to quantify the movement and the persistance of water and solutes, are valid only to a reduced extent, because just here the structure of the soil is very heterogeneous. The same is true for aquifers with large voids.