Zinc fractionation in the rhizosphere of wheat (

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

Effect of wheat (

Our purpose was to quantify the effect of rhizosphere processes on the fractions of Copper (Cu) in 10 soils amended with sewage sludge under greenhouse conditions by using a rhizobox. For amended soils, 1% (w/w) of sewage sludge was added to soil samples and then amended soils were incubated at field capacity, for 1 month. After incubation, soils were put in rhizobox and seeds of wheat were planted. Plants were harvested after 8 weeks and rhizosphere and bulk soils were separated. Fractions of Cu in the rhizosphere and bulk soils were determined. The results showed that Cu extracted using several extractants in rhizospheric soils were significantly (P<0.01) lower than in bulk soils. In the rhizosphere of amended soils the average of residual Cu, Cu associated with iron-manganese oxides, Cu associated with organic matter, Cu associated with carbonates and exchangeable Cu were 18.8, 2.10, 1.00, 0.37 and 0.24 mg kg−1 respectively, whereas above fractions in the bulk soils were 18.1, 2.43, 0.80, 0.42 and 0.30 mg kg−1 respectively. This study illustrated that Cu-fractions in the wheat rhizosphere were different compare to bulk soils in sewage sludge amended soils