Sorption of a hydrophilic pesticides: Effects of soil water content
Journal
Soil Science Society of America Journal
Journal Volume
70
Journal Issue
6
Start Page
1991
End Page
1997
ISSN
0361-5995
1435-0661
Date Issued
2006-11-01
Author(s)
DOI
10.2136/sssaj2006.0091
Abstract
Transport of pesticide to groundwater is governed in part by sorption of the pesticide to soil particles. Sorption may be dependent on soil moisture conditions, but limited data are available from which to elucidate the effect. Our objective was to determine the effect of soil water content on the sorption coefficient of a hydrophilic pesticide. Sorption of dicamba (3,6-dichloro-2- methoxybenzoic acid) was measured in three soils, each at two initial water contents. At low water contents (∼0.05 kg kg-1), sorption coefficients were similar for all three soils, ranging from 0.01 L kg -1 for the loamy sand to 0.07 L kg-1 for the silty clay loam. At higher water contents (0.19-0.24 kg kg-1), the sorption coefficient for the loamy sand was unchanged, for the silt loam it was doubled, and for the silty clay loam it was increased almost sixfold. Multiple regression analysis revealed a strong linear relationship between the sorption coefficient and the product of soil water content and organic C content (r2 = 0.86). The number of dicamba sorption sites probably increases with soil organic C content, while the accessibility of these sites appears to increase with soil water content. This may be caused by the decreasing hydrophobicity of soil organic matter with increasing water content. The effects of water content on pesticide sorption require further research and may ultimately have implications for the methods used to determine sorption and for managing pesticide application.
Subjects
Hydrophilicity
Moisture
Pesticides
Regression analysis
Soil surveys
Sorption
loamy sand
multiple regression
pesticide
soil carbon
soil water
sorption
transport process
water content
Silty clay loams
Soil moisture
Water content
Soil surveys
Publisher
Wiley
Type
journal article