Degree Type

Creative Component

Semester of Graduation

Fall 2020



First Major Professor

Dr. Antonio P. Mallarino


Master of Science (MS), Master of Agriculture (MAg)





Previous research in fields of the eastern Corn Belt with histories of soybean manganese (Mn) deficiency symptoms showed that Mn fertilization could increase soybean yield. However, more recent research on Mn across the North Central region has shown mostly no increase in soybean yield or inconsistent results. In the early 2000’s, four plus years after glyphosate resistant soybean varieties were first marketed, field observations and research sometimes observed reduced weed control from Mn and glyphosate tank mixes. Also, Indiana research found reduced Mn uptake and leaf tissue concentration in glyphosate resistant soybean with or without applied glyphosate. The objective of this study was to assess potential interactions between foliar Mn fertilization and glyphosate application in soybean fields. Four treatments (water, water with Mn, water with glyphosate, and water with a mixture of glyphosate and Mn) replicated three times were applied at the soybean R3 growth stage in a field in Indiana and another field in Ohio. Preplant soil test results and tissue testing of trifoliate leaves sampled at the R2 growth stage suggested sufficient Mn levels for soybean. Tissue test results at the R3 growth stage (after treatment application) showed no statistically significant treatment differences for Mn or other nutrients at any field. Soybean yields were accidentally lost at the Ohio field. At the Indiana field there were no statistically significant yield differences. The study confirmed previous research that showed no antagonism between glyphosate and soybean Mn nutrition when soil Mn sufficiency is optimum or higher.

Copyright Owner

Shafer, Adam

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