Sorption characteristic of Cinosulfuron in Pakistani soils along with two minerals and their statistical evaluation

Abstract

A Sulfonylurea herbicide, Cinosulfuron was investigated for its adsorption-desorption behavior on two minerals and
two Pakistani soils having different geographical conditions. This sulfonylurea herbicide is used in Pakistan against
a wide range of leafy weeds and grasses. The sorption experiments were done utilizing batch equilibrium methods.
The data obtained showed that adsorption co-efficient isotherm for Cinosulfuron in two tested soils well fitted the
Freundlich equation. The isotherm was nonlinear in all cases with slope n<1 resembling the L type curve.
Distribution co-efficient (Kd) parameters were low indicating low adsorption. Low Gibbs free energy values were
connoting the phenomena of physisorption in soils. It was observed that Cinosulfuron herbicide showed a relatively
greater degree of adsorption on soil samples collected from northern hilly areas of Ayubia, Khyber Pukhtunkhwa
(Silt loam) i.e. 25.5% and low adsorption on sandy soil of Multan, Punjab. Soil organic matter (SOM), pH and total
carbon content (TOC) were considered to be imperative factors leading to variances in sorption capacity. Their
regression and correlation was determined with adsorption distribution coefficient (r=-1, r=1 and r=1
respectively).