Residue dynamics and degradation behaviour of pyrazosulfuron-ethyl in the rice field environment

Pyrazosulfuron-ethyl is used in rice fields to manage a range of annual and perennial weeds. Its long-term herbicide residue dynamics in rice ecosystem and degradation pattern is poorly characterized. Therefore, in the present study, field experiments were conducted for consecutive two years to investigate the residue dynamics and degradation of pyrazosulfuron-ethyl in the soil, rice plant, water and fishes in the rice field. Pyrazosulfuron-ethyl residues were found to be below the maximum residues levels (0.01 mg/kg) in the soil, rice grains, and straw. In the fishes, pyrazosulfuron-ethyl residues were in the range of 0.056- 0.013 μg/g. Half-life of pyrazosulfuron-ethyl in the soil of rice field was found to be 9.41 to 13.9 days. Results showed that pyrazosulfuronethyl at 25 g/ha application rate did not cause any environmental hazards and can be safely applied in the rice fields for management of annual and perennial weeds.