Microbial Community Structure in Soils Amended With Glyphosate-tolerant Soybean Residue

Nye, Mark; Hoilett, Nigel; Ramsier, Cliff; Renz, Peter; Dick, Richard P.

doi:10.12691/aees-2-3-1

Cited by 5 publications

(4 citation statements)

References 28 publications

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“…However, even sorbed glyphosate might be available to microbial degradation (32). Additionally, it has been suggested that microbial populations in soils with a history of glyphosate exposure have adapted and can better tolerate (i.e., are less responsive) or more rapidly break down (i.e., are more responsive to) the herbicide (24,25,29,33).…”

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confidence: 99%

Impacts of Repeated Glyphosate Use on Wheat-Associated Bacteria Are Small and Depend on Glyphosate Use History

Schlatter

Yin

Hulbert

et al. 2017

Appl Environ Microbiol

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Glyphosate is the most widely used herbicide worldwide and a critical tool for weed control in no-till cropping systems. However, there are concerns about the nontarget impacts of long-term glyphosate use on soil microbial communities. We investigated the impacts of repeated glyphosate treatments on bacterial communities in the soil and rhizosphere of wheat in soils with and without long-term history of glyphosate use. We cycled wheat in the greenhouse using soils from 4 paired fields under no-till (20+-year history of glyphosate) or no history of use. At each cycle, we terminated plants with glyphosate (2× the field rate) or by removing the crowns, and soil and rhizosphere bacterial communities were characterized. Location, cropping history, year, and proximity to the roots had much stronger effects on bacterial communities than did glyphosate, which only explained 2 to 5% of the variation. Less than 1% of all taxa were impacted by glyphosate, more in soils with a long history of use, and more increased than decreased in relative abundance. Glyphosate had minimal impacts on soil and rhizosphere bacteria of wheat, although dying roots after glyphosate application may provide a "greenbridge" favoring some copiotrophic taxa. Glyphosate (Roundup) is the most widely used herbicide in the world and the foundation of Roundup Ready soybeans, corn, and the no-till cropping system. However, there have been recent concerns about nontarget impacts of glyphosate on soil microbes. Using next-generation sequencing methods and glyphosate treatments of wheat plants, we described the bacterial communities in the soil and rhizosphere of wheat grown in Pacific Northwest soils across multiple years, different locations, and soils with different histories of glyphosate use. The effects of glyphosate were subtle and much less than those of drivers such as location and cropping systems. Only a small percentage of the bacterial groups were influenced by glyphosate, and most of those were stimulated, probably because of the dying roots. This study provides important information for the future of this important tool for no-till systems and the environmental benefits of reducing soil erosion and fossil fuel inputs.

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confidence: 99%

Impacts of Repeated Glyphosate Use on Wheat-Associated Bacteria Are Small and Depend on Glyphosate Use History

Schlatter

Yin

Hulbert

et al. 2017

Appl Environ Microbiol

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“…The two glyphosate formulations tested had little or no effect on the microbial groups quantified. In this experiment, the general absence of an effect, even at twice the maximum allowed dose, may be associated to the strong adsorption of glyphosate by Fe and Al oxides and clay (Nye et al, 2014), all of which were major components of the soil used in this experiment (clay >70%; AlO3 24%; Fe2O3 25%).…”

Section: Resultsmentioning

confidence: 79%

“…Although specific for plants, herbicides not only affect the target organisms, but may also alter the ecological balance directly or indirectly (Nye et al, 2014). However, they can be biodegraded or mineralised in the environment, being of great importance for bioremediation of both soil and environment (Singh et al, 2004;Ramos and Yoshioka 2012).…”

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confidence: 99%

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Glyphosate impact on C and N microbial functional groups in soybean rhizosphere

Avanzi

Matsumoto

Albino

et al. 2019

ASB J.

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The no-tillage system requires a higher use of herbicides to control weeds before sowing, increasing the concern over the effect that such products might have on the environment. However, few studies reporting the influence of glyphosate on soil microorganisms are available in the literature. The aim of this work was to evaluate the effect of two formulations of glyphosate on functional groups of microorganisms in soybean rhizosphere. The experiment was performed in a greenhouse, and the treatments were the isopropylamine salt and the ammonium salt of glyphosate at the maximum and twice the maximum allowed dose. The control treatment had no application. The populations of soil bacteria, fungi, actinomycetes, fluorescent pseudomonas, cellulolytics, amylolytics, proteolytics and free-living N-fixing were determined by plate counts on selective media. Plant root dry weight, shoot dry weight and the number and dry weight of nodules were determined. The application of herbicides had little effect on the populations of microorganisms, as well as on plant growth. Nevertheless, the interactions among some populations of microorganisms and between these and the plant were influenced by the formulation of the glyphosate applied.

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Location, Root Proximity, and Glyphosate-Use History Modulate the Effects of Glyphosate on Fungal Community Networks of Wheat

et al. 2017

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Glyphosate is the most-used herbicide worldwide and an essential tool for weed control in no-till cropping systems. However, concerns have been raised regarding the long-term effects of glyphosate on soil microbial communities. We examined the impact of repeated glyphosate application on bulk and rhizosphere soil fungal communities of wheat grown in four soils representative of the dryland wheat production region of Eastern Washington, USA. Further, using soils from paired fields, we contrasted the response of fungal communities that had a long history of glyphosate exposure and those that had no known exposure. Soil fungal communities were characterized after three cycles of wheat growth in the greenhouse followed by termination with glyphosate or manual clipping of plants. We found that cropping system, location, year, and root proximity were the primary drivers of fungal community compositions, and that glyphosate had only small impacts on fungal community composition or diversity. However, the taxa that responded to glyphosate applications differed between rhizosphere and bulk soil and between cropping systems. Further, a greater number of fungal OTUs responded to glyphosate in soils with a long history of glyphosate use. Finally, fungal co-occurrence patterns, but not co-occurrence network characteristics, differed substantially between glyphosate-treated and non-treated communities. Results suggest that most fungi influenced by glyphosate are saprophytes that likely feed on dying roots.

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Microbial Community Structure in Soils Amended With Glyphosate-tolerant Soybean Residue

Cited by 5 publications

References 28 publications

Impacts of Repeated Glyphosate Use on Wheat-Associated Bacteria Are Small and Depend on Glyphosate Use History

Impacts of Repeated Glyphosate Use on Wheat-Associated Bacteria Are Small and Depend on Glyphosate Use History

Glyphosate impact on C and N microbial functional groups in soybean rhizosphere

Location, Root Proximity, and Glyphosate-Use History Modulate the Effects of Glyphosate on Fungal Community Networks of Wheat

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