Persistence of oxyfluorfen residues in the soil of paddy field and detection of its residues in crop produce.

摘要

There is increasing concern about persistence of pesticide residues in soils, agricultural products and subsequent contamination of groundwater. Thus persistence of oxyflourefen was evaluated under rice cropping system. Oxyfluorfen was sprayed at 150 and 300 g/ha application rates 4 days after transplanting of rice as post-emergence herbicide. Paddy grains, straw and soil samples were collected at harvest and analyzed for oxyfluorfen residues by a validated HPLC method with an accepted recovery of 85-89% at the minimum detectable concentration of 0.003 ppm. Residues of oxyfluorfen in paddy grains and straw were found below 0.003 micro g/g in lower and double the recommended dose. In the soil, 0.026 and 0.044 micro g/g residues were detected where oxyfluorfen was applied at 150 and 300 g ai/ha rates, respectively. Thus, a safe waiting period of 106 days is suggested for paddy crop after the herbicide application. Though residues were found within safe level in soil, paddy grain and straw but continuous use of oxyfluorfen in the same field may be avoided as this may lead to biomagnifications of residues in soil which then bioaccumulate in the crop produce and may enter to the aquatic system through runoff, drift and leaching and thus affect aquatic life.