Effect of preflooding on transformation of applied zinc and its uptake by rice in lateritic soils
1992
Mandal, B. | CHATTERJEE, J | HAZRA, G C | MANDAL, L N
Lateritic soils usually contain high amounts of oxides of iron, which are known to have strong zinc-binding capacity. When such soils are used for growing flooded rice and zinc is used as fertilizer, much of it is likely to be fixed by oxides of iron if it is applied immediately after flooding the soil. But if such application of zinc is made after keeping these soils preflooded for a few days, its fixation may be lowered due to the changes occuring in the oxides of iron during the preflooding period.Keeping the above in view we investigated the effect of different periods (0 and 15 d) of preflooding on the transformation of applied zinc in four lateritic ricegrowing soils into its different forms, namely (i) water soluble plus exchangeable (WSEX), (ii) organically complexed (OC), (iii) manganese oxide bound (MnOX), (iv) amorphous iron oxide bound (AMOX), and (v) crystalline oxide bound (CRYOX).Results showed that the transformation of applied zinc into WSEX, OC and AMOX forms was more, and that transformation into MnOX and CRYOX forms was less, when zinc was applied after keeping the soils preflooded for 15 days as compared to such transformation when zinc was applied immediately after flooding (0 d preflooding). This was found to be related to the changes in the forms of oxides of iron and manganese during the period of preflooding.Results of a greenhouse experiment showed that uptake of applied zinc by rice was more when it was applied after 15 d than after 0 d preflooding. Results suggest that use efficiency of applied zinc for rice in lateritic soils can be improved if its application is delayed by 15 d after flooding the soils.
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