Decomposition of the herbicide EPTC in soils with a history of previous EPTC applications

The degradation of the herbicide EPTC ( S ‐ethyl N , N ‐dipropylthiocarbamate) in 3 soils, with and without, previous field exposure to this herbicide was investigated. The influence of storage of soil (12 months) on the subsequent breakdown of EPTC was investigated. Soils with added EPTC were incubated (22°C), and the fate of EPTC was followed using gas liquid chromatogaphy. The herbicide degraded more rapidly in soils with 3 and 4 years of previous' exposure to annual applications of EPTC (6kg/ha) than in those soils without any previous exposure. This more rapid decomposition was evident after storage of soils for I year at ambient temperatures. Microorganisms were responsible for EPTC degradation in these soils. Some of the implications of this phenomenon on soil ecology are discussed.