This study aims to find the effect of both geogenesis and pedogenesis on soil
fertility status in south Sinai wadis (Sidri and Feiran). Nine soil profiles in different
physiographic units characterizing the study area were selected to represent their
associated parent rocks, which in turn related to different parent rocks (basement
complex, sedimentary and mixed "sedimentary with igneous and metamorphic". The obtained data reveal that the total content of soil nutrients P, K, Fe, Mn,
Zn and Cu were markedly influenced by the type of parent rocks from which soils
were derived. The highest values are associated with the soils of igneous and
metamorphic parent rocks (wadi feiran and its delta) followed by the soils of mixed
parent rocks (marine sediments). The lowest values were found in the soils of
sedimentary parent rocks (wadi Sidri and its delta, piedmonts plain and bajada). The values of available soil nutrients were affected by pedogenic processes
and sedimentation regime. The soils in wadis of either igneous and metamorphic or
sedimentary parent rocks include higher contents of available P, K, Fe, Mn, Zn and
Cu than the soils in other units. This are related to the geomorphic process. The
vertical distribution of available P, K, and Mn in vegetated soils (wadis) show a relative
higher levels in soil surface (ecosystem). According to Soltanpour evaluation, the nutrient rating are high to medium for
P, K, Mn, Zn and Cu in the soils of wadis (Feiran and Sidri). Fe and Mn are adequate
in all physiographic units while, K is medium in bajada. For each nutrient, the rest of
physiographic units are suffering from the nutrient deficiency, which be needed as
fertilizers for such soils. The mineralogical examination of light and heavy minerals reveal that the
nutrient bearing minerals assemblage are achieved in feldspars as the main source
for K and Ca. A relatively high content of these minerals were found in the soils of
wadis and coastal braided delta (either derived from igneous and metamorphic or
sedimentary parent rocks), reflected their soil potentiality for these nutrients. As for
heavy minerals, the studied soils were characterized by abundance of opaques (as a
source of Fe). Pyroxenes and amphiboles (Ca, Mg and Fe), epidotes (Ca and Fe),
biotite (K, Mg and Fe) and Apatite and monazite (P), comprise a relatively high portion
of the non opaque minerals, especially for the soil derived from the igneous and
metamorphic parent rocks. Thus these soils are potentially rich in these elements,
comparing with the other· soils.