Degradation of pyraclonil in three typical soils

To clarify the degradation behavior of pyraclonil in the environment. The indoor simulation test method was used to study the degradation characteristics of pyraclonil in purplish soil, paddy soil and red soil under the conditions of anaerobic, aerobic and sterilized. The results showed that the degradation of pyraclonil in those three soils accorded with the first-order kinetic equation. Under aerobic conditions, the degradation half-lives in purplish soil, paddy soil and red soil were 13.4 d, 10.1 d, and 31.1 d, respectively. And the degradation rates were positively correlated with the organic matter and clay content in the soils. The degradation rates under different conditions were in the order of anaerobic > aerobic > sterilization, which indicated that the degradation of pyraclonil in the soil was affected by the hydrolysis and microbial activity. Within a certain range of soil water holding capacity, the degradation rate of pyraclonil in the soil was improved with the increase of soil water content. This study demonstrated that the degradation rate of pyraclonil was relatively fast and the residue period was short under the condition of flooding in paddy field. This work provided a scientific basis for the rational use of pyraclonil and its environmental safety evaluation.