Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/24/2000
Publication Date: N/A
Technical Abstract: Conservation tillage practices have been promoted as a means of achieving a more sustainable farming system by minimizing soil losses due to erosion. However, this practice generally leaves farmers with few options for pest control other than chemical pesticides. In a two-year field study carried out on a 141-ha field, we have evaluated the impact on shallow groundwater quality of transition from conventional till to no-till for three herbicides used in minimum-till corn/soybean systems. Metolachlor, nicosulfuron, and imazethapyr were studied. Well water samples were obtained using manual bailers and residue analyses were carried out in our laboratory. Methods utilized cartridge chemistry followed by HPLC/MS/MS techniques, providing a 50 part per trillion quantitation limit for 1-L of filtered ground water. Results confirm that these widely used families of weed control chemicals are capable of leaching to shallow water table depths during tillage transition and after only a few years of application under central Iowa precipitation patterns.