Chapter 14 - Textural Pedofeatures and Related Horizons

Abstract

Textural pedofeatures are characterised by a difference in grain size with the adjacent groundmass and comprise coatings, infillings, silt cappings, infillings and intercalations. Because the most prominent textural pedofeatures are clay coatings, this chapter focuses mainly on this type of textural feature, its development and occurrence not only in soil horizons. Many field and laboratory experiments were carried out with the aim of investigating the genesis and formation of clay coatings. Nevertheless, it is hardly possible to infer from micromorphological data alone if the illuvial clay is a result of (i) vertical translocation from the overlying horizon, (ii) lateral translocation, or (iii) translocation processes within the same horizon. The correct recognition and description of clay coatings is the key to a precise interpretation of genesis and properties of the horizons and soils under consideration. Illuvial clay coatings are often difficult to recognise in the field, but in most cases they are easily distinguishable under the microscope. So far, micromorphology is the only reliable method to validate clay illuviation and it also provides additional information about the conditions of formation of the various textural illuvial features.