Effect of different chelating agents and bioinoculants on fractional distribution of cadmium and nickel in spiked soil after harvest of Indian mustard (Brassica Juncea)

Abstract

Screen house experiment was conducted t o study the different forms of Cadmium (Cd) and Nickel (Ni) in the soil after harvest of Indian mustard (Brassica juncea L.) as affected by chelating agents and bioinoculants from metal enriched soil. A seven-step sequential extraction procedure was applied to evaluate the association of metals with soil constituents. The different chemical forms of fraction of Cd and Ni extracted were exchangeable + water soluble carbonate, organic matter complexed, Mn-oxide bound, occluded in amorphous and crystalline Fe-oxide and residual mineral fraction. The present study revealed that dominant Cd fraction was organic followed by carbonate, Manganese oxide, exchangeable, crystalline Fe-oxide, amorphous Fe-oxide and residual Cd fraction. Application of chelating agents increased the exchangeable fraction causing an increase in its availability in the soils. It may be ascribed that application of chelating agent caused an increase in the exchangeable fraction of Cd with a consequent decrease in carbonate, organic, Mn-oxide, AFe- oxide and CFe-oxide bound fractions. Highest amount of exchangeable fraction was observed in EDTA treated soil. Application of FYM and vermicompost increased organic and carbonate fraction of Cd but decreased other fractions. In bioinoculants treated soil, addition of FYM and vermicompost increased organically bound fraction of Cd (greater than non-bioinoculants treated soil). Application of chelating agent (EDTA) significantly increased the exchangeable fraction of Cd with a consequent decrease in carbonate, organic, MnOX, AFeOX, bound fractions. Application of FYM and vermicompost increased organic and carbonate fraction of Cd but decreased other fractions. In bioinoculants treated soil, addition of FYM and vermicompost increased organically bound fraction of Cd. Fractionation of soil Cd after the harvest of Brassica juncea crop showed that the application of chelating agent (EDTA) excellently improved the exchangeable pool of Cd.

Screen house experiment was conducted t o study the different forms of Cadmium (Cd) and Nickel (Ni) in the soil after harvest of Indian mustard (Brassica juncea L.) as affected by chelating agents and bioinoculants from metal enriched soil. A seven-step sequential extraction procedure was applied to evaluate the association of metals with soil constituents. The different chemical forms of fraction of Cd and Ni extracted were exchangeable + water soluble carbonate, organic matter complexed, Mn-oxide bound, occluded in amorphous and crystalline Fe-oxide and residual mineral fraction. The present study revealed that dominant Cd fraction was organic followed by carbonate, Manganese oxide, exchangeable, crystalline Fe-oxide, amorphous Fe-oxide and residual Cd fraction. Application of chelating agents increased the exchangeable fraction causing an increase in its availability in the soils. It may be ascribed that application of chelating agent caused an increase in the exchangeable fraction of Cd with a consequent decrease in carbonate, organic, Mn-oxide, AFe- oxide and CFe-oxide bound fractions. Highest amount of exchangeable fraction was observed in EDTA treated soil. Application of FYM and vermicompost increased organic and carbonate fraction of Cd but decreased other fractions. In bioinoculants treated soil, addition of FYM and vermicompost increased organically bound fraction of Cd (greater than non-bioinoculants treated soil). Application of chelating agent (EDTA) significantly increased the exchangeable fraction of Cd with a consequent decrease in carbonate, organic, MnOX, AFeOX, bound fractions. Application of FYM and vermicompost increased organic and carbonate fraction of Cd but decreased other fractions. In bioinoculants treated soil, addition of FYM and vermicompost increased organically bound fraction of Cd. Fractionation of soil Cd after the harvest of Brassica juncea crop showed that the application of chelating agent (EDTA) excellently improved the exchangeable pool of Cd.