Iron forms in some egyptian soils

The present study is an attempt to find out the available forms of iron (Fe2+ and Fe3+) in five egyptian soils samples, representing alluvial, calcareous and sandy soils. Concerning the iron content of soil either Fe2+ or Fe3+, the tested soil types were relatively arranged in the order alluvial> calcareous> sandy soil. In spite of the considerable variations in the soil content of iron cations, the Fe2+/Fe3+ ratio was almost kept constant around 0.83. The uniformity of the ferrous : ferric ratio in the different tested soil types indicates their similarity in their redox-potential, pH and their environmental conditions, particularly, the aeration and partial O2- pressure degree. Fe2+/Fe3+ being less than unity suggests that the Fe2+ Fe3+ reaction tends towards the forward direction, i.e., to the Fe3+ formation. As a result of the pot experiment, significant correlations have been found between the laboratory determined soil Fe2+ and both of the plant Fe-uptake and the plant dry matter weight