INFLUENCE OF TIME ON RELEASE BEHAVIOUR OF ZINC AND ITS FRACTION IN DIFFERENT PHOSPHORUS STATUS SOILS

Zinc in soil exists in different chemical forms, while its total concentration does not provide accurate information about its bioavailability, the application of fractionation approach provides information on the metal's actual and potential availability.In this study, an incubation experiment was conducted to evaluate the influence of time on DTPA-extractable Zn and Zn fractionation in two different phosphorus status soils.The study's findings show that in both kinds of soil, the release of DTPA-extractable Zn and all other Zn fractions consistently decreased during the course of incubation.Although the pattern of DTPA-extractable Zn release and its fractions remained same but their amounts were noticeably different across the two soils, reflecting their varying capacities for continuous supply of Zn to the soil solution.Based on the results, comparison of the values shows that the concentration of DTPA-extractable Zn and its fractions for high P status soil was more than low P status soil.Moreover, Zn fractions followed the same order for both the soils, viz.RES-Zn > Fe/MnOX-Zn > CAR-Zn > ORG-Zn> WSEX-Zn.Among the fractions in both the soils, RES-Zn was the dominant fraction that contributed most to the total-Zn, followed by Fe/MnOX-Zn, whereas, the contribution of WSEX-Zn fraction to the total-Zn was relatively low.