Soil diversity and properties in mountainous subtropical areas, in Sierra Sur de Oaxaca, Mexico

Abstract

Agroforestry is a new practice of sustainable soil use in the mountainous Sierra Sur de Oaxaca area of Mexico. Coffee is also a common cash crop grown in the region. The objective of this study was to investigate the pedodiversity in the area. Soil development is very complex, and is influenced by slope parameters and parent materials. Several soil groups are found in the area investigated: Alisols, Umbrisols, and Cambisols. Morphology, chemical properties, and mineralogical composition of the clay fraction of these soils were studied. The soils vary in the extent of weathering, morphology, and chemical properties, which are important to farming in the area. Most of the soils have heterogeneous parent material. The distribution of major soil types of the area is related to mass movement along the slopes, both past and present. The studied soils represent a chronosequence from unleached and unweathered Cambisols to Alisols, characterized by strong clay illuviation and dominance of kaolinite and gibbsite in clay fraction. A mosaic of landslides and gullies of various ages, formed by catastrophic events such as earthquakes and hurricanes, form the pedodiversity of the area studied. Key words: Landslides, chronosequence, pedodiversity, Cambisols, Umbrisols, Alisols