Effects of glyphosate on soil microorganisms

Black soil in northeast region of China was used to investigate the effects of glyphosate on soil respiration,soil cultural bacteria,Rhizobium japonicum and Fusarium oxysporum,to provide a theoretical basis for the evaluation of environmental safety of glyphosate.The results showed that increasing glyphosate concentration increased the inhibition on soil respiration.When glyphosate concentration in soil were 1mg·kg-1,10mg·kg-1 and 100 mg·kg-1,the risk index were 1.20,0.322 and 0.076,which were less than the standard index of 20.Glyphosate influenced quantities of soil fungi and actinomycetes.High glyphosate concentration increased the inhibition to population of soil cultural bacteria.With the extended application of glyphosate,soil fungus,bacteria and actinomycetes populations had been restored.Actinomycetes were more sensitive to glyphosate than fungus and bacteria,and soil bacteria had a strong tolerance or degrading ability to glyphosate.Glyphosate impacted on inhibiting Rhizobium japonicum and Fusarium oxysporum,and the inhibition of Rhizobium japonicum was in direct proportion with the concentration of glyphosate.Low glyphosate concentration promoted Fusarium oxysporum populations,while high concentration inhibited them.The extended application time of glyphosate decreased the inhibition of glyphosate on Rhizobium japonicum and Fusarium oxysporum.