Persistence and carryover effect of oxyfluorfen residues in red sandy clay loam soil

A Field experiments were conducted for two years at Agricultural Research Station, Bhavanisagar of Tamil Nadu Agricultural University, Coimbatore, India during kharif season of 2010 and 2011 to evaluate the new formulation of oxyfluorfen (23.5% EC) on weed control in onion and their residual effect on succeeding crops. Herbicides are being chemical in nature, excessive and repeated use may pose phytotoxicity to crop plants, carryover effects on succeeding crops and also leads to adverse effects on non-target organisms. This might due to causes of health hazards to humans, animals and the environment. Many herbicides are bound residues which make them not only unavailable to the targets, but also polluting the soil ecosystem in a number of ways. Thus monitoring of herbicides residue in soil, plant and other matrixes are very much important. Therefore, a laboratory and field experiments were undertaken to investigate the persistence of oxyfluorfen in soil and onion crop under red sandy clay loam soil. Based on two years field experimentation, phytotoxicity symptoms of oxyfluorfen was complete recovery of affected on onion got completely recovered plant could be observed subsequently in 30 days after herbicide application (DAHA); and the phytotoxicity was not evident thereafter in onion plant. Field persistence of oxyfluorfen at varying doses applied in soil and residue content in onion plant sample were well below the prescribed maximum residue limits (0.05 μg g-1) at the time of harvest. Residue of oxyfluorfen herbicide dissipated faster in plant than in soil. It is highly bound to the soil organic carbon and has low mobility in red sandy clay loam soil which indicates the binding of this herbicide to soil particles is high. Bioassay results showed that the oxyfluorfen herbicide to be secure on the succeeding crops and this might be due to detoxification of herbicide in soil and do not adversely affect the growth and yield attributes of the succeeding crops.