Effect of hexachlorocyclohexane on methane production and emission from flooded rice soil

Application of commercial formulation (an isomeric mixture) of hexachlorocyclohexane (HCH) to flooded rice fields planted to cv. Rasi at 1 kg active ingredient.ha(-1) significantly inhibited methane emission. Negative relationship existed between methane emission from HCH-treated fields and root oxidase activity (in terms of alpha-naphthylamine oxidised). Under laboratory conditions, the addition of technical grade alpha-, beta-, gamma- and delta-isomers (99.1% purity) of HCH, individually at 20 mu g.g(-1) soil at flooding, effected a distinct inhibition of methane production. Evidence suggests that the inhibitory effect of all the four isomers on methane production only until 20-25 days after their application was related to their persistence in flooded soil. (C) 1997 Elsevier Science Ltd.