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United States Department of Agriculture

Agricultural Research Service

Title: Field Studies of Imidacloprid Distribution Following Application to Soil Through a Drip Irrigation System

Authors
item Felsot, Allan - WASHINGTON STATE UNIV.
item Evans, Robert
item Ruppert, Judy - WASHINGTON STATE UNIV.

Submitted to: American Chemical Society Symposium Series
Publication Type: Proceedings
Publication Acceptance Date: November 1, 2002
Publication Date: December 2, 2002
Citation: FELSOT, A.S., EVANS, R.G., RUPPERT, J.R. FIELD STUDIES OF IMIDACLOPRID DISTRIBUTION FOLLOWING APPLICATION TO SOIL THROUGH A DRIP IRRIGATION SYSTEM. AMERICAN CHEMICAL SOCIETY SYMPOSIUM SERIES 842. E.L. ARTHUR, V.E. CLAY AND A. BAREFOOT, EDITORS. 2002. PP. 189-205.

Interpretive Summary: Both surface and subsurface drip irrigation can reduce overland flow and thereby reduce surface transport of pesticides. Little is known, however, about leaching of pesticides when applied via drip systems. A series of experiments were conducted over several years to characterize the horizontal and vertical distribution of imidaclopid [1-[6-chloro-3-pyridinyl)methyl]-N-nitro-2-imidazolidinimine] in an experimental hop yard under subsurface drip irrigation.

Technical Abstract: Both surface and subsurface drip irrigation can reduce overland flow and thereby reduce surface transport of pesticides. Little is known, however, about leaching of pesticides when applied via drip systems. A series of experiments were conducted over several years to characterize the horizontal and vertical distribution of imidaclopid [1-[6-chloro-3-pyridinyl)methyl]-N-nitro-2-imidazolidinimine] in an experimental hop yard under subsurface drip irrigation. The insecticide pipe buried 45-60 cm deep on each side of a hop vine row. Water exited the pipe through labyrinth emitters spaced at 90-cm intervals. Soil profiles of either 105 cm or 150 cm in depth were collected at various times following chemigation to characterize imidaclopid distribution in successive 15-cm soil layers. Imidaclopid residues were mostly confined to soil profiles collected within a 30-cm radial distance from an emitter. When irrigation occurred on a 4-h daily time schedule (treatment 4H), imidaclopid leached to the lowest depths sampled (105 or 150 cm). Imidaclopid leaching was comparatively less extensive in two of the three trials that studies irrigation scheduling triggered on and off by soil moisture sensors recognizing pre-defined soil matric potentials (irrigation treatment MP). Pseudo-first order half-lives of imidaclopid ranged from 18 d in 4H treatments to 31 d in MP treatments. All dissipation rates were faster than previously reported for field studies at other locations. The effect or analyzing duplicate profile samples individually rather than analyzing them as bulked composites was investigated in a randomized treatment design experiment. Individual analyses of replicate plot duplicates significantly lowered the overall treatment mean standard deviation, suggesting an improved potential for resolving differences in residue distributions that may result from changes in irrigation management practices.

Last Modified: 9/10/2014
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