Chapter 4 Soil morphology

Abstract

Publisher Summary Morphology is the most important feature used to differentiate Vertisols from other soil orders. The major morphological markers of Vertisols are linear and normal gilgai (micro-relief), cyclic horizons, surface cracking upon desiccation, and slickensides. Soil structure is also peculiar, especially the occurrence of wedge-shaped aggregates. Slickensides between aggregates are the most characteristic feature of Vertisols. The most striking morphological characteristics are associated with swelling and shrinking on alternate wetting and drying cycles. Vertisols were believed to be homogeneous, but recent studies showed that morphological and other characteristics are very complex. The differences in degree of expression of any morphological characteristics reflect the differences in chemical, physical, mineralogical, and environmental conditions. The morphological characteristics of Vertisols, without giving any reference to their genesis, are discussed in the chapter. It describes macromorphology and micromorphology of vertisols. Macromorphology includes gilgai, nature of cyclic horizons, cracking, surface granular structure, slickensides and sphenoids, color, depth, carbonates and Fe and Mn segregations, clay distribution, and bulk density. These characteristics may not be all present in Vertisols, except for slickensides. Micromorphology is used to determine the direction of pedogenic processes rather than quantify the magnitude of such expressions.