Introduction

The degradation of plant and animal matter, i.e. the release and binding of nutrients and trace elements, is one of the most important functions of soil organisms. The task of the soil fauna is to loosen the soil, and to diminish and to mix the litter. The microorganisms are important for the enzymatic degradation of the complex organic substances to nutrients and for the release of nutrients and trace elements from the mineral soil fraction. Soil microorganisms include bacteria, fungi and algae, as well as the mycorrhizae, which contribute to better plant development. Further, there are many pathogenic plant and animal fungi in the soil. The sensitive reaction of the soil microflora to external influences results in a quick adaptation to the new conditions, but also in a changed reaction towards the plants.