METRIBUZIN SORPTION DYNAMICS IN ACID SOILS OF NZOIA SUGARCANE ZONE IN WESTERN KENYA
Date
2011Author
Lagat, Silas C
Lalah, Joseph O
Kowenje, Chrispine O
Getenga, Zachary
Chepkui, Richard
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The adsorption, desorption and leaching of metribuzin in agricultural soil samples taken
from Nzoia sugarcane farming area in Kenya were determined using standard methods. The
Freundlich adsorption isotherm constants (Kf and 1/n) were found to be 0.54 µg/g and 0.61
µg mL-1, respectively. 94.9% of the residues were recovered after 6 hours of the desorption
test and 93.7% of applied dose was found in the leachate after 9 hours of leaching in a soil
column. The adsorption curves indicated L-type of adsorption for 0.1, 1.0 and 2 µg L-1 initial
pesticide concentrations and S-type for the 5 ppm initial concentration with peak
equilibrium adsorption established after 4 hrs of exposure for the 0.1, 1.0, 2.0 µg L-1,
respectively, and after 6 hours for the 5 µg L-1 initial concentration. Although the
metabolites were not determined, HPLC analysis showed that degradation was rapid and
started to occur after 4 hours of exposure, influencing its adsorption isotherms