Influence of a commercial formulation of tridemorph on methane production and oxidation in a tropical rice soil

In a laboratory incubation study, application of a commercial formulation of tridemorph to a tropical rice soil under flooded condition significantly stimulated CH4 production at low levels (5, 10 and 20 mu g.g(-1)) but inhibited the process at higher levels of 50 and 100 mu g.g(-1). Oxidation of CH4, however, was progressively inhibited with increasing concentrations of the fungicide. Increase in CH4 production in tridemorph-amended soil was attributed to a hastening in the soil reduction, increase in the K2SO4-extractable C content and an increase in the population of methanogenic bacteria. Inhibitory effect of the fungicide on the oxidation of CH4, on the other hand, was related to the inhibition in the population of methanotrophic bacteria. (C) 1999 Elsevier Science Ltd. All rights reserved.