A MICROMORPHOLOGICAL APPROACH TO THE INTERACTIONS BETWEEN SOIL STRUCTURE AND SOIL BIOTA

Micromorphology is the qualitative and quantitative analysis of undisturbed soils and other consolidated materials, usually in thin sections, using microscopic and submicroscopic techniques. It can be applied to a wide range of sciences. Micromorphology has rarely been used in soil ecology, but techniques developed and being developed offer ample applications. This paper focuses on specific micromorphological techniques, old and new, used to study interactions between soil structure and soil biota. The main ones were: preparation methods to prevent the shrinkage of organic materials and clays; staining techniques to mark conductive voids and different organic materials, and lastly photographic methods to produce adequate images with enough contrast for measurements to be made by image analyses. Two preparation methods, freeze drying and acetone replacement led to good results. Conductive voids were stained with a methylene blue solution and a number of of organic tissues could be coloured with safranine O. Structure analyses were performed on mounted photographs, taken under rotating crossed polarizers and plain transmitted light, in which only the voids were black. Examples of results from the Dutch Programme on Soil Ecology of Arable Farming Systems are given.