Adsorption of oxadiargyl and butachlor on soil particle size separates
2012
Rao, P.C. | Lakshmi, Ch. S. Rama | Madhavi, M. | Swapna, G. | Sireesha, A.
Study on adsorption of oxadiargyl and butachlor was carried out on soil particle size separates of four type of soils from different agroclimatic zones of Andhra Pradesh using batch equilibration technique. Irrespective of the particle size, the per cent adsorption was more in vertisols than alfisols. Among four soils studied, maximum adsorption (59.7 ìg/g) was observed in 0.05 mm soil separate of vertisol-2, whereas minimum adsorption of 4.5 ìg/g was observed in 2 mm soil of alfisol-1. The amount adsorbed increased with increase in initial concentration and reached a plateau. The isotherms were mainly parabolic in nature with 'S' shaped tendency. The S-shape reflected the initial resistance to the adsorption of herbicides, to overcome later by the cooperative effect of adsorbed molecules. Soil low to medium in organic carbon, has a tendency to give S-shaped isotherms on account of their hydrophilic nature as compared to soil high in organic carbon which tend to be hydrophobic. The adsorption maxima was positively and significantly correlated with organic carbon content. Freundlich 'Kf' values which indicate the extent of binding of herbicide to the soil constituents were positively and significantly correlated with organic carbon, clay content and clay + organic carbon.
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