Soil Developmental Stages of Layered Cambisols and Calcisols on Socotra Island, Yemen

Abstract

Semiarid tropical regions are very suitable to study the polygenesis of layered substrates and soils. To determine relic and recent soil features of tropical soils, pedons in the northern part of Socotra Island, Yemen, were investigated. The aim of the study was to create developmental stages of widely distributed soils, which in particular are layered Cambisols and Calcisols. In most layers of those investigated soils, denudative components occur, which clearly indicate the relocation of coverloams and coverclays with an incorporation of extraneous materials, such as small pieces of relic clayey loams with different shapes. These fragments indicate strong chemical weathering, preceding erosion, and redistribution and/or embedding into younger sediments. Calcium carbonate found at a depth of up to 30 cm in 52% of the layered soils is very typical of an increasing aridity in parts of the semiarid tropics, particularly in areas with high groundwater levels and interflow. In addition, oxidation features and clay illuviation in noncalcareous substrates were detected. At the end, two major soil developmental stages of layered Cambisols and Calcisols were defined and demonstrated at two selected profiles. We assume that patterns of soil polygenesis depend not only on the composition of the respective substrates but also on changing climate conditions. Geochemical and soil physical methods as well as micromorphological analysis were used to describe and classify the soils.

Archaeopedological analyses around a Neolithic hearth and the beginning of Sabaean irrigation in the oasis of Ma'rib (Ramlat as-Sab'atayn, Yemen)

“…Periodically sayls may have brought sufficient water to support the development of a weak soil mainly represented by partial decalcification with corresponding ironhydroxide precipitation and residual clay enrichment, well known from other dry tropical areas (Khormali et al, 2003;Pietsch and Kü hn, 2009). Since soil formation also modified the sediment filling of the fireplace (Bwkb horizons) to the same degree as the adjacent buried land surface, some time must have passed before the area around the fire place was irrigated.…”

Terrace soils in the Yemen Highlands: Using physical, chemical and radiometric data to assess their suitability for agriculture and their vulnerability to degradation

“…Soil and climate change research in Yemen conducted in recent years has highlighted these drastic climatic changes Geoderma 185-186 (2012) [48][49][50][51][52][53][54][55][56][57][58][59][60] in Southern Arabia (e.g. Fleitmann et al, 2007;Lézine et al, 2007;Parker et al, 2006;Pietsch and Kühn, 2009;Sirocko et al, 1993;Wilkinson, 2005). Few studies of afforestation, a very important strategy for soil protection and for combating soil erosion, have been reported in Yemen.…”

Soil formation in loess-derived soils along a subhumid to humid climate gradient, Northeastern Iran

“…Argillic horizons in calcareous soils of arid to semiarid regions characterized by limited leaching may indicate periods of more humid climatic conditions in the past. Pietsch and Kuhn (2009) reported that calcium carbonate found at a depth of up to 30 cm in most of the layered soils is very typical of an increasing aridity in parts of the semiarid tropics, particularly in areas with high groundwater levels and interflow.…”