Abstract

Sixty surface (0-20 cm) soil samples were collected each from the paddy fields of villages in Gangavati taluka in North Karnataka during 2010. Distributions of different forms of zinc in paddy growing soils were studied. The results showed that more than 75% (79.38%) in Herura village and more than 90% (99.35%) in Maralanahalli village of total zinc occurred as residual zinc, whereas water soluble + exchangeable Zn accounted for only 0.11% in Maralanahalli village and 6.71% in Sanapura village soil samples. The water soluble + exchangeable zinc status varied from 0.13 to 1.93 ppm, organically bound zinc from 0.16 to 5.32 ppm, manganese oxide bound zinc from 1.00 to 5.89 ppm, amorphous sesquioxides bound zinc from 0.09 to 2.16 ppm, crystalline sesquioxides bound zinc form 1.21 to 9.94 ppm and residual zinc from 53.29 to 277.99 ppm. Among the Zn fractions water soluble + exchangeable zinc was low in all the soils when compared to other fractions, which is a very important for the plant nutrition. Amorphous sesquioxide bound form of zinc is the seat for zinc adsorption because of its high specific surface area. Crystalline sesquioxide bound form of zinc dominated when compared to water soluble + exchangeable, organically bound, manganese oxide bound and amorphous sesquioxide bound zinc fractions in selected village soils in Gangavati taluka.

Keywords: Zinc fractions, paddy soil, water soluble and exchangeable zinc, organically bound zinc, amorphous sesquioxide bound zinc, residual zinc, total zinc