The mobility, transport and partitioning of Zn in soils are dependent on various soil chemical properties such as soil pH, the type and contents of clay minerals, organic matter and the carbonates. The objective of this study was evaluation and comparison of zinc fractions, in native and treated soil with three levels of zinc: 0, 5 and 10 μg Zn kg-1 soil as ZnSO4. 7H2O, before and after removal of calcium carbonate by three sequential extraction methods. Calcium carbonates were removed from soil samples by the sodium acetate (NaOAc adjusted in pH = 5) and Hydrochloric Acid (HCl). Result shown that removal of carbonate led to decrease in total zinc for all samples but, there were significant differences in the Zn fractions (relative percentage) before and after carbonate removal at native soil and treated soil. Removal of calcium carbonate (in 3 methods) led to decrease in residual fraction and increase in other forms (except organic fractions and water-soluble) for rinsing with Hcl samples (for all methods) and also, led to slight decrease in residual fraction and slight increase in other forms (except organic fractions and water soluble) for rinsing with NaAOC samples. Generally, the results shown that soil chemical properties, such as calcium carbonate can influence fractions of zinc and convert soluble forms to insoluble forms.
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