Sorption behaviour of oxadiazon in tropical rice soils

• Published in: Water science and technology Vol. 56; no. 1; pp. 115 - 121
• Main Authors: Hoque, M.E, Wilkins, R.M, Kennedy, A, Garratt, J.A
• Format: Journal Article
• Language: English
• Published: England IWA Publishing 01-01-2007
• Subjects: Adsorption; alluvial soils; Capacity; carbon; chemical equilibrium; Chemical Phenomena; Chemistry, Physical; Correlation coefficient; Correlation coefficients; duration; environmental fate; equations; Herbicides; Isotherms; Kinetics; linear models; Linearity; Mathematical models; Molecular Structure; Organic carbon; Oryza; Oryza sativa; Oxadiazoles - analysis; Oxadiazoles - chemistry; Oxadiazon; radionuclides; rice soils; Soil; Soil - analysis; Soil investigations; Soil Pollutants - analysis; soil pollution; Soils; Sorption; sorption isotherms; Tropical Climate; tropical soils; Bangladesh
• ISBN: 9781843395973; 1843395975
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2007.442

The soprtion behaviour of a pre-emergent herbicide, oxadiazon (5-tert-butyl-3-(2,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazol-2 (3H)-one) was investigated in tropical rice soils using a batch equilibrium method. There is no information available on the fate of oxadiazon in Bangladeshi soils; Bangladesh rice soil is a unique environment. The experiment was performed using radiolabelled (14C) oxadiazon. The sorption and desorption isotherm of oxadiazon was described using the Freundlich equation. L-type sorption isotherms were observed. The correlation coefficient (r2) was 0.995 to 0.997 and the linearity of the slope was in the range 0.96-1.07. Sorption of oxadiazon was related to organic carbon. Sorption of oxadiazon by soil was a rapid process; sorption kinetics indicated that most of the sorption occurred within two hours. Changes in sorption of oxadiazon by soils was investigated by repeated application. Sorption after the first cycle was in the range 81-92% whereas sorption capacity decreased in the following cycles.