In terrestrial ecosystems, soil microorganisms and soil animals are essential for litter degradation, soil formation and the availability of nutrients and trace elements. The measurement of biological soil parameters allows a rapid evaluation of the effects of chemical and physical influences due to pollutants or soil management. This book introduces a number of well proved methods for the analysis of carbon, nitrogen, phosphorus and sulfur cycles. It focuses further on the determination of the number and biomass of microorganisms, algae and animals in the soil. Particular emphasis is placed on the comprehensible and complete description of the experimental procedures.