Accelerated microbial breakdown of carbofuran in soil from previously treated fields

Abstract

Microbial degradation of carbofuran was rapid in acid mineral soil collected from fields in Prince Edward island, Nova Scotia, New Brunswick and Ontario with a history of use of this insecticide and with pH ranging from 6.1 to 6.6. Concentrations of carbofuran ranging from 10 to 5000 ppm (μg active ingredient per g of over-dry-soil) degraded to levels not detectable by bioassay (< 0.2 ppm) in less than 1 day at 10 ppm, to in about 90 days at 5000 ppm. Concentrations of 200, 300 and 500 ppm of 10% carbofuran granules degraded almost as quickly as a 100-ppm application, but 1000, 2000 and 5000 ppm degraded more slowly. Soil from fields with a natural pH lower than 5.8 have not shown any evidence of rapid microbial breakdown of carbofuran.