Degradation of pesticides applied to banana farm soil: Comparison of indigenous bacteria and a microbial mat

Abstract

AbstractIndigenous bacteria from St. Vincent (West Indies) banana farm soil, enriched cultures of three isolates, and a microbial mat were tested for their ability to degrade carbofuran, chlordane, paraquat, and prophos. In single‐pesticide application experiments, only 35.0% of the parent carbofuran was recovered after 21 d; paraquat recovery was 40.0%, and chlordane, 91.0%. In a mixture containing each pesticide, 42.0% of the parent carbofuran was recovered, and paraquat and chlordane recoveries were 52.0% and 94.0%, respectively. A microbial mat and the isolates were shown to mineralize [14C]carbofuran. Best results (93.11 μg [14C]carbofuran/kg dry microbial mat) were from a 15‐d dark soil experiment. In field trials, the concentration of carbofuran decreased 82% with microbial mat treatment, and control plot concentrations actually increased 26%, The concentration of prophos decreased significantly after 4 d (0–6 mg/kg) in the plots with a microbial mat, whereas in control plots it increased from 7 to 12 mg/kg at day 0 to 180 mg/kg at day 4. After 60 d prophos was not detected in any microbial mat plot, whereas all but one control plot had it (0–12 mg/kg) in the soil.