Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 6, 2004
Publication Date: November 15, 2004
Citation: Graff, C.D., Rice, C., Sadeghi, A.M., Bialek-Kalinski, K.M. 2004. Evaluating the field dissipation of atrazine, metolachlor and selected metabolites by quantifying the water extractable phase. ASA-CSSA-SSSA Annual Meeting Abstracts. 96th Annual Meeting, Seattle, WA Oct. 31 - Nov. 4, 2004, pg. 165. Technical Abstract: The water extractable phase of a pesticide should reasonably estimate the amount of chemical that can potentially be exported from agricultural systems due to the fact that soil and surface water are the key transport media for such compounds. Quantification of water extractable metolachlor, atrazine, and a suite of their respective metabolites in surface soils has been carried out on a sub-watershed at the Beltsville Agricultural Research Station. Soils were collected on a regularly spaced geo-referenced grid in order to identify a spatial component to dissipation. After uniform application, surface soil samples were collected at 2, 4, 6, 15 and 30 d. Results indicate less than 10% of initial concentrations remaining in surface soils 15 d after application. A simultaneous gradual increase in metolachlor ethane sulfonic acid and metolachlor oxanilic acid occurred until 6 d after application and then increased significantly by the 15th day. The atrazine metabolites OIET, CEAT, and CIAT also increased until 6 d after application, but then decreased over the next 15 d after application. Metabolites of both metolachlor and atrazine are present even on the day of application, evidencing the rapid degradation of both compounds. Differences in the dissipation patterns for both compounds at the individual sample locations were also observed.