An Investigation of Oxidoreduction Condition and Some Electrochemical, Chemical and Mineralogical Characteristics of Paddy and Nonpaddy soils

Ponding of unsaturated soils and the final resulted redox conditions, cause different chemical and electrochemical changes. Redox potential is one of the most effective factors in determination of chemical properties of ponded soils; as by influencing dissolution and sedimentation of minerals and the activity and uptake of soil nutrients. The study site with an extension area of area about 10 ha is located in the Rice Research Station (West of Tonekabon County). Considerable Test Results were developed in morphological, physical and chemical characteristics of the studied pedons. For this purpose, Eh, such different forms of iron such as soluble, crystalline, amorphous and total iron along with mineralogy of the redoximorphic features in 7 pedons were studied. The Eh values decrease by increase in soil organic matter under similar anaerobic conditions. Relatively higher organic matter contents (0.35-11.57 %) of the studied soils play an important role in strong complexification of iron and the level of its different forms [Fe-DTPA (8.45-206.64 ppm), Fe-o (0.37-1.3 %), Fe-cd (0.5-5.78 %), Fe-t (3.06-8.19 %)]. Comparison of EDS elemental analyses data revealed that Fe contents were rather higher in redoximorphic features than those in the soil matrix. Mineralogical composition of redoximorphic features showed that lepidochrosite is the dominant form of Fe in both reduced paddy as well as in nonpaddy soils.