Keywords: Chemical Forms of Iron, Concentration, Corn, Iron Uptake, Sequential Extraction

Iron (Fe) is the most important micronutrient for crops that has low availability in calcareous soils. Phytoavailability of Fe depends on the relative distribution of different chemical Fe forms in soil, which is function of soil properties. In this greenhouse research, total Fe fractionated into different forms by sequential extraction procedure was studied in 21 soil samples that varied in physical and chemical properties. According to the results, different Fe fractions concentration were as: Residual iron (Fe-Res)> iron associated with the crystalline iron oxides (Fe-CFeOX)> iron associated with the amorphous iron oxides (Fe-AFeOX)> manganese- oxide- associated Fe (Fe- MnOX)> organic matter-associated Fe (Fe-OM)> exchangeable iron (Fe-Ex) ≥ carbonates-bound iron (Fe-Car). Fe-Ex, Fe-OM, Fe-AFeOX, Fe-CFeOX, Fe-Res and available iron (Fe-DTPA) had a significant relationship with corn shoot and root dry matter, active iron content, chlorophyll index and shoot iron uptake. Correlation coefficient showed that the Fe-Ex, Fe-AFeOX and Fe-Res had a close and significant relationship with all measured agronomical traits of corn. It is concluded that, these forms of iron are probably the source of available iron for corn in studied soils.