Integrated evaluation of variation in biological, chemical and physical soil properties

The importance of biological processes for soil functioning is frequently stressed. In spite of this, the biological soil component has seldom been used to assess soil quality, while optimal and threshold values have been identified for many physical and chemical soil parameters. In this investigation, the variation in a number of microbiological, chemical and physical variables was studied on two scales. Small scales were studied with 52 samples from a single agricultural field, and large scales with a set of 26 samples from very diverse agricultural sites in Sweden. In addition, the functional structures of the two scales were studied by means of principal component analysis (PCA). The two scales had more similarities than dissimilarities regarding variable variation and functional structures. The relationships between variables were, however, more blurred in the large than in the small scales as the influences of soil structure, climate and cropping practice were larger. The possibilities to reduce the number of variables without loss of vital information about the soil system are discussed.