Influence of kinetic sorption and diffusion on pesticide movement through aggregated soils

TY - GEN

T1 - Influence of kinetic sorption and diffusion on pesticide movement through aggregated soils

AU - Beulke, S

AU - Brown, C D

AU - Fryer, C J

PY - 2003

Y1 - 2003

N2 - Laboratory studies were carried out to investigate the availability of isoproturon for leaching at different times from application depending on initial soil moisture status. Initially dry and initially wet aggregates of a heavy clay soil were treated with the pesticide and incubated at 90% field capacity and 15degreesC. Samples were taken at intervals, filled into small leaching columns and irrigated. Soil water was extracted from parallel samples by centrifugation to characterise the fraction of isoproturon available for leaching under natural moisture conditions. Total soil residues were determined at each interval. Isoproturon losses in leachate decreased with time. The rate of decrease was similar to that for the mass in soil water which suggested that the centrifugation technique used may be suitable to characterise the fraction of the pesticide that is readily available for leaching. Leaching losses declined faster than would be expected from degradation alone. This phenomenon is likely to be caused by diffusion of the pesticide into soil aggregates where it is less available for leaching and time-dependent sorption processes. There was no significant influence of soil moisture conditions at the time of application on the leaching of isoproturon or its availability in soil water.

AB - Laboratory studies were carried out to investigate the availability of isoproturon for leaching at different times from application depending on initial soil moisture status. Initially dry and initially wet aggregates of a heavy clay soil were treated with the pesticide and incubated at 90% field capacity and 15degreesC. Samples were taken at intervals, filled into small leaching columns and irrigated. Soil water was extracted from parallel samples by centrifugation to characterise the fraction of isoproturon available for leaching under natural moisture conditions. Total soil residues were determined at each interval. Isoproturon losses in leachate decreased with time. The rate of decrease was similar to that for the mass in soil water which suggested that the centrifugation technique used may be suitable to characterise the fraction of the pesticide that is readily available for leaching. Leaching losses declined faster than would be expected from degradation alone. This phenomenon is likely to be caused by diffusion of the pesticide into soil aggregates where it is less available for leaching and time-dependent sorption processes. There was no significant influence of soil moisture conditions at the time of application on the leaching of isoproturon or its availability in soil water.

KW - kinetic sorption

KW - diffusion

KW - leaching

KW - soil structure

M3 - Conference contribution

SN - 88-7830-359-3

SP - 211

EP - 216

BT - PESTICIDE IN AIR, PLANT, SOIL & WATER SYSTEM

A2 - DelRe, AAM

A2 - Capri, E

A2 - Padovani, L

A2 - Trevisan, M

PB - LA GOLIARDICA PAVESE

CY - 27100 PAVIA

ER -