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The lethal effect of herbicide butachlor (2-chloro 2,6diethyl N, butoxymethyl acetanilide) on the
earthworm Eutyphoeus waltoni was evaluated in different combination of feed materials under the
laboratory conditions. Eutyphoeus waltoni were exposed to different concentrations of butachlor
(0.3, 0.6, 0.9, 1.2 mg/kg) in feed material i.e. buffalo dung, wheat straw and gram bran and soils for
time range from 24 to 240h.The maximum toxicity was observed in the Sandy soil 24, 48, 72, 96,
120, and 240h with LC50 values ( 95% of confidence limits) estimated by probit analysis were 0.952
(0.689 to 2.071), 0.652 (0.486 to 0.852), 0.543 (0.346 to 0.724), 0.449 (0.246 to 0.602), 0.388 (0.127
to 0.533) and 0.287 (0.056 to 0.432), respectively. There were dose and time dependent increase in
the mortality rate due to exposure to the herbicide. Maximum toxicity was observed in the sandy soil
whereas, minimum in combination of buffalo dung with gram bran.
Keywords: Toxicity, Herbicides, Butachlor, Earthworm, Soil, Buffalo dung, Agro-wastes.