Abstract
The application of the insecticide carbofuran (technical or formulated) to rice rhizosphere soil suspensions at 10 and 100 ppm (mug/ml) of active ingredient distinctly stimulated the autotrophic oxidation of ammonium. Evidence suggested that Nitrosomonas sp. was enriched in the presence of carbofuran. Formulated carbofuran (Furadan 3G) exhibited a more pronounced stimulation of ammonium oxidation than that exhibited by technical-grade (99.5%) carbofuran, a result which was attributed to the CaCO(3) present in the formulation.