Glyphosate is a systemic post-emergent herbicide of the non-selective organophosphate group widely used in apple orchards in the South of Brazil. It may have adverse effects on beneficial soil microorganisms. The aim of this study was to evaluate the biodegradability of glyphosate by soil microbiota in apple orchards with different histories of application of the product. For that purpose, soil samples from the region of Vacaria, Rio Grande do Sul, were used, with the biodegradation of glyphosate being evaluated by monitoring the release of CO2 by microorganisms over 32 days, as well as quantifying the residues of glyphosate and its metabolite, aminomethylphosphonic acid (AMPA), at the beginning and end of the period through extraction followed by analysis by high performance liquid chromatography (HPLC). The results showed that there was glyphosate degradation by soil microorganisms during the period evaluated, with formation of the metabolite AMPA. Glyphosate decreased the number of soil bacteria, but favored increased microbial activity. The bacteria present in soils with lower herbicide exposure showed more degradability of the product when compared to those found in soils with a greater period of glyphosate application.
glyphosate; biodegradation; herbicide; AMPA; microorganisms
