Behavior and Distribution of Free Iron Oxides in Some Soil Orders in Iraq

Abstract

This study was conducted to investigating the behavior of free iron oxides in some soil orders in Iraq. Soil samples were collected from five Pedons for soil orders Entisols, Aridisols, Inceptisols, Vertisols and Mollisols. Total free iron oxides (Fed) were extracted by CBD, amorphous iron oxides by acid ammonium oxalate and iron oxide linked with organic matter by alkaline Sodium pyrophosphate. the distribution of iron oxides in (Fep) to crystallized iron oxides were compared. The results showed that (Fed-Feo) there is no particular direction that controls the vertical distribution of Fed Mollisols and Vertisols pedons excelled in the content of Fed compared to the other orders. Amorphous Feo accumulates in surface horizons and Mollisols pedon was excelled on all pedons in Feo content followed by Vertisols, Inceptisols, Aridisols and Entisols. The Pedons of Inceptisols, Aridisols and Entisols soil order contain higher amounts of crystalline Fed-O oxides compared to the Mollisols and Vertisols as well the vertical distribution taken a different pattern for all pedons. (Fep) was low compared to other forms of iron oxides and is accumulated in surface soil horizon in all pedons.