Detoxification of glyphosate in soil

Detoxification of glyphosate in not-autoclaved and autoclaved soils was followed by bioassay with wheat. Comparisons are made with detoxification of MCPA under similar conditions followed by bioassay with spring rape. The well known pattern for microbial metabolism of MCPA with a ‘lag’-phase preceding the rapid degradation was shown. The initial rapid inactivation of glyphosate is by adsorption, but the results also clearly indicate that the further disappearance of activity mainly depends on microbial degradation. Glyphosate does not seem to sustain microbial growth, which indicates that it is degraded by co-metabolism. In autoclaved soil the possibility of a slight chemical degradation or an adsorption that becomes stronger with time could not be excluded.