Zinc fractionation in the rhizosphere of wheat (Triticum aestivumL.) plant in soils treated with sewage sludge

Rhizosphere is a microbiosphere and has quite different chemical, physical and biological properties from bulk soils. A greenhouse experiment was performed to compare fractionation of Zinc (Zn) between rhizosphere and bulk soils amended with sewage sludge (1% w/w of sewage sludge to soil). Fractions of Zn were determined in two subsamples (rhizosphere and bulk soils). The results indicated concentration of Zn-fractions (except carbonates-associated) in the rhizosphere soils were significantly (p<0.05) different from concentrations of Zn-fractions in the bulk soils. Also, results revealed that significant correlation (p<0.05) between Zn associated with iron-manganese and yield and uptake indices in the rhizosphere and bulk soils were found. The results of this research illustrated that rhizosphere is a small zone but important environmental zone in soils with quite different properties.