Abstract: This paper studied the residue of chlorpyrifos and its degradation dynamics in Chinese chive (Allium tuberosum) plant and soil after irrigating different concentrations of this pesticide into A. tuberosum root zone under plastic greenhouse and open-field cultivated conditions. The chlorpyrifos  in A. tuberosum plant had a faster degradation rate than that in soil, with an average half-life of the pesticide being 3.41 and 7.40 days in the plant and soil, respectively. Under the conditions of plastic greenhouse and open-field cultivation, the degradation rate of chlorpyrifos in A. tuberosum plant had less difference, with the average half-life of chlorpyrifos being 3.37  and 3.44 days, respectively. 21 days after irrigating into root zone, the chlorpyrifos (0021-0102 mg·kg-1) in A. tuberosum plant did not exceed the maximum residue limit (≤0.01 mg·kg-1, GB 2763—2005). A few chlorpyrifos residue was found in the new growth parts of A. tuberosum, but the residue concentration was obviously lower than that in the first harvested plant after irrigating this pesticide. The chlorpyrifos residue in soil had significant effects on the residue of the pesticide in A. tuberosum plant.

Key words: soil, Allium tuberosum, chlorpyrifos, pesticide degradation