INFLUENCE OF THE HERBICIDE GLYPHOSATE ON SOIL MICROBIAL COMMUNITY STRUCTURE

The side effects of glyphosate on the soil microflora were monitored by applying a range of glyphosate concentrations (0, 2, 20, and 200 μg g-1 herbicide) to incubated soil samples, and following changes in various microbial groups over 27 days. Bacterial propagule numbers were temporarily enhanced by 20 μg g-1 and 200 μg g-1 glyphosate, while actinomycete and fungal propagule numbers were unaffected by glyphosate. The frequency of three fungal species on organic particles in soil was temporarily enhanced by 200 μg g-1 glyphosate, while one was inhibited. One species was temporily enhanced on mineral particles. However, many of these fungi were inhibited by 200 μg g-1 glyphosate in pure culture. There was little agreement between species responses to glyphosate in incubated soil samples and in pure culture. © 1990 Kluwer Academic Publishers.