1 STUDIES ON GENESIS, CLASSIFICATION AND EVALUATION OF SOME SOILS

ABSTRACT Egypt soils are generally characterized by slightly alkaline to alkaline pH values which are mainly due to its dry environment. Under such aridic conditions, the occurrence of acid soils is considered an anomalous, and interesting to be studied. Three acid soil profiles, located at El-Wahat El-Bahrya, Giza Governorate, Egypt were investigated for this study. The field description indicated the occurrence of common iron oxides, jarosite and clay-iron cutans. Except the Ap horizon of profile 3, all the pH values of the studied soils were acidic and ranged between 3.63 to 5.15, which is mainly considered due to the oxidation of pyrite that was formed during an old more humid period. The chemical analysis assured the presence of exchangeable acidity and low cation exchange capacity due to the dominance of kaolinite clay mineral. The results were confirmed by the x-ray diffraction and transmission electron microscope examinations, which indicated the dominance of kaolinite clay minerals and the presence of ferric oxides and jarosite. Both skell-ferriargillans and the undulic plasmic fabric were identified by the micromorphological inspection confirming the formation of kandic horizon in the studied soils. The soils are classified mainly as “Typic Haplosalids and "Plinthic Kandiudalfs”. All the soils have kandic horizons that were pedologically developed on ferruginous sandstone materials during different paleo-environments and were preserved under the recent arid conditions within which some salic horizons are formed. The suitability of the studied soils for irrigated agriculture was evaluated as S2 and S3 classes. Integrated environmental management is recommended for the area to conserve soils from the irruptive degradation that occur mainly due to the mismanagement activities