Physical and Chemical Characteristics of Ghazallat Region, Siwa Oasis, Western Desert, Egypt

Abstract

Siwa Oasis is a closed depression situated in the north western portion of the Western Desert of Egypt between Longitudes 25º 16' and 26º 12' E, and Latitudes 29º 06' and 29º 24' N. Three soil profiles were selected to represent the main geomorphic units and their associated soil groups in the studied area. Ghazallat soils are characterized mainly by sand and sandy loam textures, as well as sandy clay loam in the deeper layers. The chemical analyses of soil solution indicate that the cultivated soil samples show slightly saline to moderately saline nature, whereas the soils under reclamation and the barren ones are strongly saline. In general the organic matter contents are low, while CaCo3 content increases from the deeper samples to the higher ones. As for the soil reaction of Ghazallat area, it is clear that these soils are ranging from mildly to moderately alkaline. It is noticed that Na + cation > Mg ++ , Ca ++ and Mg ++. The predominance of Na + and Mg ++ is a good reflection of the involvement of marine origin of the soils. On the other hand, the anionic distribution has the following descending order Clanion > SO 4-> HCO 3-, where CO 3-is almost negligible. The distribution of the fertility elements are of low to moderate levels. The bulk samples analysis indicates that quartz, calcite, feldspars (albite) minerals are the main dominant mineral associations in all soil profiles of Ghazallat region. Dolomite and anhydrite as well as gypsum presented in some depths of soil profiles. Illite and kaolinite represent the identified clay minerals in the studied soil samples. The radiometric studies show that all of the studied soils in the area are not related to the uraniferous soils (uranium content not exceeding 6ppm).