The stability of iron chelates in calcareous soils

Iron in Fe-EDTA was more fixed than in Fe-CDTA. The fixation increased by increasing the ionic strength. The values of the retardation factor showed that this parameter depended more on the surface area of the soil than on the ionic strengths or CaCO3 content. The product of the reaction rate of fixation with the retardation factor depends on CaCO3-content, surface area of the soil, ionic strength and chelating agent used. It can be taken as an index of the efficiency of the iron chelate under different conditions. Fe-EDTA was more absorbed than Fe-CDTA, the adsorption increased with increasing ionic strength and surface area of the soil.