Micromorphological Techniques in Research and Teaching (Submicroscopy)

Abstract Submicroscopic micromorphological studies are usually started after field and light microscopic investigations. Submicroscopy, apart from testing machines and developing techniques, is therefore strongly dependent on previous sample selection procedures and sample preparations. Statistically determined sampling strategies are important in the field and, subsequently, in light microscopy, image analysis and submicroscopy. Sample preparation is also important because impregnating the samples with plastics, freeze-drying, ultramicrotomy and micromilling produce artefacts. These artefacts, together with the ones caused by microbeam damage in submicroscopic machines, must be known in order to avoid faulty data and conclusions. Submicroscopy can be broadly subdivided into the study of the morphology and imaging of soil materials and pores, and the chemical and microchemical analysis of soil components. For morphology studies, a digital output instead of micrographs for rapid processing by image analyzers is advisable. This is certainly necessary for three dimensional research. Besides the scanning electron microscope, machines for computed tomography, magnetic resonance imaging and confocal laser scanning microscopy can possibly be used for 3D analysis of soils. Instruments, mainly developed for analytical physics, can be used to investigate even trace elements in thin sections and true surface sections of soil components. A variety of instruments, which could augment the electron microscopes used most by soil micromorphologists, are now available for submicroscopic research.