Persistence of Butachlor and Pretilachlor in a Non Flooded Lateritic Soil

The persistence and bioefficacy of butachlor and pretilachlor in rice-rice system in a lateritic soil with and without farm yard manure (FYM) is reported. Initial residues (at one and 15 d after spraying, DAS) of butachlor and pretilachlor in soil were significantly higher in the treatments with organic manure. However, at 30 DAS and at the time of harvest, the residues did not differ significantly among the treatments. The enhanced degradation of herbicides over time in the presence of organic matter is apparently responsible for it. Higher levels of pretilachlor residues compared to butachlor were observed (0.121 and 0.056 μg g⁻¹ for the treatments pretilachlor+ FYM and butachlor + FYM respectively) at 15DAS. The enhanced retention in the FYM treated plots was reflected in the weed control and crop yield.