Urmia University Applied Soil Research 2423-7116 4 1 2016 08 22 Distribution of Soil Iron Chemical Forms in some Golestan Province Soils Distribution of Soil Iron Chemical Forms in some Golestan Province Soils 28 38 20202 FA Gholamreza Nodehsharify Esmaeil Dordipour Mojtaba Barani Motlagh Mohsen Olamaee 4- دانشیار گروه علوم خاک، دانشکده آب و خاک دانشگاه علوم کشاورزی و منابع طبیعی گرگان Journal Article 2016 11 12 Iron is one of the essential micronutrients for plants. The various components of soil elements differ significantly from each other in terms of reactivity and bioavailability. The purpose of this research was to study the distribution of different forms of Iron among the various soil components and the relationships between the metal components with some soil characteristics. So, an experiment was carried out on 10 samples collected from different areas of Golestan province with different chemical and physical properties. Fractionation of soil iron was determined via Singh et al (1988)’s sequential extraction procedure. For investigating the relationship among the various forms of soil iron with dry matter, concentration and uptake of iron, a factorial pot experiment on <em>Glycine max</em> cv. Williams in a completely randomized design (10 types of soil at first factor and two iron fertilizer levels (0 and 20 Fe mg kg-1) at second factor), with three replications was also conducted. The results showed that the amounts of iron chemical forms were ordered as follows: carbonates-bound < exchangeable < OM-bound < Mn oxides-bound < amorphous Fe oxides-bound < crystalline Fe oxides-bound < residual forms. DTPA-extractable iron showed significantly a positive correlation with exchangeable, Mn oxides-bound and crystalline Fe oxides-bound fractions (r=0.54**, r=0.60** and r=0.41*, respectively). Application of iron sequestrene caused an increase in chlorophyll index and concentration and uptake of iron. The OM-bound fraction indicated significantly positive and negative correlations with dry weight (r=0.41**) and the number of chlorotic leaves (r= -0.33*), respectively. Mn oxides-bound form was significantly and positively correlated with iron uptake (r=0.35*) and chlorophyll indices of intact and bottom leaves (r=0.37** and r=0.53**, respectively). The soil exchangeable (r=0.51**), OM-bound (r=0.37*) and residual forms (r=0.57**) and total iron (r=0.46*) showed significantly positive correlations with soil clay content. A single extraction with DTPA is not able to estimate a plant available iron; therefore, in this regard the iron different forms and clay content of soil should be also considered. Iron is one of the essential micronutrients for plants. The various components of soil elements differ significantly from each other in terms of reactivity and bioavailability. The purpose of this research was to study the distribution of different forms of Iron among the various soil components and the relationships between the metal components with some soil characteristics. So, an experiment was carried out on 10 samples collected from different areas of Golestan province with different chemical and physical properties. Fractionation of soil iron was determined via Singh et al (1988)’s sequential extraction procedure. For investigating the relationship among the various forms of soil iron with dry matter, concentration and uptake of iron, a factorial pot experiment on <em>Glycine max</em> cv. Williams in a completely randomized design (10 types of soil at first factor and two iron fertilizer levels (0 and 20 Fe mg kg-1) at second factor), with three replications was also conducted. The results showed that the amounts of iron chemical forms were ordered as follows: carbonates-bound < exchangeable < OM-bound < Mn oxides-bound < amorphous Fe oxides-bound < crystalline Fe oxides-bound < residual forms. DTPA-extractable iron showed significantly a positive correlation with exchangeable, Mn oxides-bound and crystalline Fe oxides-bound fractions (r=0.54**, r=0.60** and r=0.41*, respectively). Application of iron sequestrene caused an increase in chlorophyll index and concentration and uptake of iron. The OM-bound fraction indicated significantly positive and negative correlations with dry weight (r=0.41**) and the number of chlorotic leaves (r= -0.33*), respectively. Mn oxides-bound form was significantly and positively correlated with iron uptake (r=0.35*) and chlorophyll indices of intact and bottom leaves (r=0.37** and r=0.53**, respectively). The soil exchangeable (r=0.51**), OM-bound (r=0.37*) and residual forms (r=0.57**) and total iron (r=0.46*) showed significantly positive correlations with soil clay content. A single extraction with DTPA is not able to estimate a plant available iron; therefore, in this regard the iron different forms and clay content of soil should be also considered. https://asr.urmia.ac.ir/article_20202_8dc25458d3ada9939376115b5ab2c3dd.pdf