Morphology and Genesis of Some Soils in Saudi Arabia

Abstract

This publication deals with morphology, properties and genesis of major- soil groups acquiring morpho-pedogenic horizons. The prevailing climatic conditions divide the region into two different zones, these are: the arid-hyperthermic and ustic-thermic climatic zones. Within the aridic-hyperthermic zone, changes ascribed to pedogenesis deal with the soluble fraction of the plasma and include: accumulation of salts, gypsum or lime to form salic, gypsic or calcic horizons, respectively. Despite the significant influences of pedogenesis on morphology of soil profiles, their properties are largely determined by those of the parent material. Soils on the ustic-thermic zone appear with much more advanced stages of profile development. Changes ascribed to pedogenesis in these soils include: removals of the easy soluble part of the mobile fraction, additions of organic matter to form mollic epipedon, illuvation of clay to form argillic horizons and liberation of iron from Fe-bearing minerals.