AbstractThe enantioselective degradation of quizalofop‐ethyl and its metabolite quizalofop‐acid in two soils, a Wuhan acidic soil and a Baoding alkaline soil, was investigated. The dissipation of quizalofop‐ethyl consisted of two phases, a rapidly deceasing first phase that lasted 1 day and a slowly decreasing second phase that extended till the end of the incubation. It is shown that S‐quizalofop‐ethyl degraded slightly faster than R‐quizalofop‐ethyl in the two soils. Further incubation of enantiopure enaniomers showed that quizalofop‐ethyl was configurationally stable in soil. Quizalofop‐acid was produced quickly, and its amount reached a maximum at 1–6 days time and then decreased slowly with half‐lives ranging from 11 to 21 days. The results also showed that quizalofop‐acid degraded faster in the acidic Wuhan soil than in the alkaline Baoding soil. At last, significant enantiomerization from S‐quizalofop‐acid to R‐quizalofop‐acid was observed, and the enantiomerization was fast, resulting in residues enriched with R‐quizalofop‐acid whatever racemic quizalofop‐ethyl or pure enantiomers were initially applied in the soils. Chirality 24:552–557, 2012. © 2012 Wiley Periodicals, Inc.