Geomorphic features and soil formation of arid lands in Northeastern Jordan

Arid and semiarid lands occupy about one-third of the Earth's land surface. Interpretation of soil formation and geomorphic features of arid lands is needed to assess their soil ecological potentials, limitations, problems and management needs. The objective of this paper was to study the geomorphic features and soil formation of the arid lands in northeastern Jordan, to provide information that could be used by land managers in the study area and other arid land areas. Five representative soil pedons were excavated and described in the field. Soil samples from each horizon per pedon were taken to the laboratory for chemical and physical analyses. Geomorphic features of the area were also studied. Most of studied land surfaces are plains where eolian deflation has exposed loose gravels consisting predominantly of pebbles forming desert pavements. Desert pavements cover most of the land surface, excluding the mud playas, and are composed of basalt clasts. The accumulation of calcium carbonate and gypsum within these soils create problems for their agricultural development. Accumulation of eolian fine-grained silt has resulted in the formation of a vesicular horizon. The climatic variations during the late quaternary and the late Holocene periods contributed to the development of the desert pavement and the vesicular horizons. Clay illuviation and argillic horizon development within these soils is assumed to be a relict feature from more humid climates during the Quaternary. Sustainable agricultural development of such arid lands may not be easy. In general, these soils have high erodibility, high runoff generation potential, high susceptibility to seal and crust formation, poor water-holding capacity, pedon hardening and structural instability.