MORPHOLOGY, GENESIS AND CLASSIFICATION OF SURFACE CRUSTS IN LOAMY AND SANDY SOILS

In an attempt to organize the knowledge of soil crusting processes and to group soil crusts on the basis of common morphological features and physical properties, we synthesized and reinterpreted information from previous publications. As a result, we propose a classification system for surface crusts formed by rainfall in loamy and sandy soils. Although this system does not aim to be comprehensive, it was designed from the study of a great number of crust samples collected in the temperate and tropical zones, thus corresponding to a wide range of environmental and land use conditions. Three main classes of crusts: structural, erosion and depositional, were distinguished, each with subclasses. Where possible, correspondence has been made with former systems.This system helps predict infiltrability in accounting not only for total porosity of surface crusts but also for pore shape and continuity. Since crust classes are genetically related, this classification system also supplies some insight into predicting soil degradation and selecting the most suitable control techniques.