Skip to Main Content
 

Global Search Box

 
 
 

ETD Abstract Container

Abstract Header

Microbial Community Structure in Soils Amended With Glyphosate Tolerant Soybean Residue

Nye, Mark Edward
http://rave.ohiolink.edu/etdc/view?acc_num=osu1396272020

Abstract Details

2014, Master of Science, Ohio State University, Environmental Science.
Glyphosate is a broad-spectrum herbicide used extensively worldwide to control broadleaf weeds in agriculture. Research suggests that repeated application causes a change in soil microbial properties which could be affecting soil quality and productivity. Glyphosate tolerant (GT) soybean technology is valuable to farmers because it reduces the use of other herbicides, is as a critical for weed control in reduced tillage systems, and is generally regarded as having low environmental impacts. However, after using this technology for 10 or more years, field observations by farmers and emerging research suggest that long-term glyphosate usage is having cumulative non-target effects on soils and crops. The research of GT relative to soils and crop productivity has been mixed and often inconclusive. However, most of this research was short-term lab and field studies that did not investigate soils that had been under long-term GT cropping (10+ years). Indeed, there is now anecdotal evidence that long-term repeated application of glyphosate has a detrimental effect on GT crop yields, including non-GT crops grown in rotation with GT crops. Another aspect of GT cropping is the potential effects on soils by the GT crop residue. Nearly all of the research to date has been on glyphosate added directly to soil with little information on the effects of GT plant residue that was exposed to glyphosate. Therefore, the objective of this study was to analyze soil microbial communities during decomposition of biomass from plants grown in soil that have been exposed to glyphosate in soils with and without a history of glyphosate exposure. An experiment was designed to mimic eight years of field applications in a 24 month greenhouse study. Soybean residues from this experiment were used in an laboratory incubation study and incubated in soils with and without a history of glyphosate exposure. These soils were profiled using phospholipid fatty acid analysis to determine shifts in soil microbial community structure due to the addition of GT residues to soil. The results showed that microbial shifts during decomposition of GT soybean residue varied between soils with or without long-term exposure to glyphosate. There was also a trend that GT material that had been exposed to glyphosate cause a differential shift in the communities over GT residue that had not been exposed to glyphosate. Commercially available glyphosate formulations have two major types of salt carriers; potassium salt and isopropylamine salt, which could be a factor besides glyphosate in affecting the chemistry of GT residues and subsequently microbial response during decomposition. However, the results showed that carrier did not significantly affect PLFA profiling in soils with or without history of glyphosate exposure. Ratios of saturated to monounsaturated PLFAs in combination with ratios of specific monounsaturated PLFAs to their cyclopropane precursors are used as indicators of microbial stress. Our results showed that there were significant differences in nutritional and water stress between soils with and without a history of glyphosate exposure. There were also significant differences in stress between glyphosate residue treatments in soil with a history of glyphosate exposure.
Richard Dick, PhD (Advisor)
Warren Dick, PhD (Committee Member)
Olli Tuovinen, PhD (Committee Member)
80 p.
Ecology; Environmental Science; Microbiology; Soil Sciences
glyphosate; glyphosate-tolerant; microbial community structure; PLFA; soybean

Recommended Citations

Citations

  • Nye, M. E. (2014). Microbial Community Structure in Soils Amended With Glyphosate Tolerant Soybean Residue [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1396272020

    APA Style (7th edition)

  • Nye, Mark. Microbial Community Structure in Soils Amended With Glyphosate Tolerant Soybean Residue. 2014. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1396272020.

    MLA Style (8th edition)

  • Nye, Mark. "Microbial Community Structure in Soils Amended With Glyphosate Tolerant Soybean Residue." Master's thesis, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1396272020

    Chicago Manual of Style (17th edition)

osu1396272020
719
© 2014, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.