THE EFFECT OF GLYPHOSATE ON SOIL MICROBIAL COMMUNITIES THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By

...................................................................................................................... iii ACKNOWLEDGEMENTS ............................................................................................... vi VITA ................................................................................................................................. vii LIST OF TABLES ............................................................................................................ xii LIST OF FIGURES ......................................................................................................... xiii CHAPTER 1: THE EFFECT OF GLYPHOSATE ON SOIL MICROBIAL ACTIVITY, COMMUNITY STRUCTURE, AND SOIL POTASSIUM: AN INCUBATION STUDY 1 ABSTRACT ................................................................................................................... 2.................................................................................................................. 2 INTRODUCTION ......................................................................................................... 4 MATERIALS AND METHODS ................................................................................. 10 Soils ......................................................................................................................... 10 Experiment I: Glyphosate Use History and Rate of Application ............................ 11 Experiment II: Repeated Application Incubation .................................................... 12 Soil Analytical Methods .......................................................................................... 13 Statistical Analysis .................................................................................................. 15 ix RESULTS .................................................................................................................... 17 Experiment I: Glyphosate Use History and Rate of Application ............................ 17 Experiment II: Repeated Application Incubation .................................................... 19 DISCUSSION .............................................................................................................. 21 TABLES ....................................................................................................................... 25 Table 1.1. Properties of Soils. ................................................................................. 25 Table 1.2. Fatty Acid Methyl Esters used as Biomarkers for Taxonomic Grouping ................................................................................................................................. 26 Table 1.3. Fatty Acid Methyl Ester Ratios used in Data Analysis .......................... 27 Table 1.4. Percentage difference in respiration rate ................................................ 28 LIST OF FIGURES ..................................................................................................... 29 Figure 1.1 ................................................................................................................ 31 Figure 1.2 ................................................................................................................ 32 Figure 1.3 ................................................................................................................ 33 Figure 1.4 ................................................................................................................ 34 Figure 1.5 ................................................................................................................ 35 Figure 1.6 ................................................................................................................ 36 REFERENCES ............................................................................................................. 37