Mineralogical and Micromorphological Properties of Oued Righ Region Soils in the Northern Sahara of Algeria

Soil resources and their quality in the desert region of Oued Righ, located in northeastern Algerian Sahara, have emerged as unifying concepts to approach the larger issue of sustainability of oasian ecosystems in general, and agriculture in particular. This study aims to characterize and classify using physicochemical, mineralogical and micromorphological analyses, thirteen pedons located in different landscapes positions, including butte, plateau, piedmont, alluvial plain, playa, and claypan, to provide information about the genesis, classification, and properties of the Oued Righ soils. The results showed that the parent materials (calcareous and gypsiferous), as well as the topographic conditions, greatly influence soil development and its distribution in the study area. The soils of the Oued Righ region are generally slightly alkaline and saline, have coarse texture, especially at the soil surface, and are very rich in gypsum accumulations. These soils are classified as Aridisols and Entisols. The clay mineralogy results revealed that detrital input and inheritance are possibly the main sources of palygorskite, kaolinite, smectite-chlorite, and illite. Thin-section observations revealed that calcite coatings on grains and voids, calcite nodules and gypsum macro- and microcrystals were common pedofeatures observed in the studied soils. Hence, the actual hydrological regime in the study area is not compatible with the data obtained; therefore, the majority of pedons should be considered as paleosols.