Behavior and Distribution of Free Aluminum Oxides in some Soil Orders in North of Iraq

Abstract

This study was conducted to investigate the behavior of free aluminium 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 aluminium oxides (Ald) were extracted by (striate-bicarbonate, sodium dithionite), amorphous aluminium oxides by acid ammonium oxalate and aluminium oxide associated with organic matter by alkaline Sodium pyrophosphate. The results showed that the amorphous aluminium oxides followed the same behavior in the vertical distribution and did not take a homogeneous pattern among the study pedons, noting that the Vertisols and Mollisols had outperformed the rest of the orders when it was observed that the highest values of 1.42 g / kg soil appeared in the horizon Ck1 of the Mollisols order, and that the highest values of the active ratio Alo/Ald also appeared in these two orders, which reflects the effect of the development state of the soil in releasing larger amounts of these oxides. Crystalline aluminium oxides appeared at lower values than the amorphous form in the Vertisols and Mollisols, unlike the Entisols, Aridisols and Inceptisols, in which these values excelled, noting that the values of crystalline oxides were somewhat superior in Vertisols. The aluminium oxide associated with the organic matter was concentrated in the surface horizons of all the study pedons, and the degree of soil development had no effect on that.