Rhizosphere interactions: the root microbiome
Dunfield, Kari .
Microbial ecology and biogeochemical cycling in the rhizosphere of corn (Zea mays).
Soil microorganisms play a vital role in many important ecosystem functions that influence soil and crop productivity. There is ample evidence that the diversity of plant-associated bacterial communities can change in response to plant genotypes, and that management practices such as growing genetically modified crops, using conventional tillage practices and the harvest of agricultural residues for biofuels can affect the abundance and/or activity of soil organisms. Any agricultural management practice that alters microbial community structure is a concern because these microbial communities are a fundamental component of the soil food web and are responsible for many crucial soil processes, such as greenhouse gas emissions, nutrient transformations, crop decomposition, carbon storage, and soil structure. In my talk I will provide a brief overview of how soil communities respond to crop management strategies and present the results of research studies conducted at the at the University of Guelph in Ontario Canada focusing on greenhouse gas emissions. Nitrous oxide (N2O) is the most important greenhouse gas emitted from agroecosystems and is a byproduct of microbial nitrification and denitrification processes. In a long-term assessment measuring N2O emissions at our field site it was determined that in a corn-soybean-wheat rotation, using best management practices, that included no-tillage, decreased N2O emissions significantly compared to conventional management practices, and that the majority of the annual emissions occurred during spring thaw. Using molecular techniques we examined the diversity and abundance of microbial communities involved in the nitrogen cycle, and determined that environmental conditions that lead to significant N2O emissions from soil are also associated with alterations in the active microbial community. This is the first work to relate changes in abundance of active of nitrifiers and denitrifiersto year round field-scale measurements of N2O. The interaction between microbial communities, plants and tillage systems, along with the seasonal variability in microbial communities documented in this study emphasizes the complexity and need for a multifaceted approach to study the diversity of the microbial community in the rhizosphere.
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1 - University of Guelph, School of Environmental Sciences, Alexander Hall, Guelph, ON, N1G2W1, Canada
soil microbial community
Presentation Type: Symposium or Colloquium Presentation
Location: Delaware D/Hyatt
Date: Tuesday, July 10th, 2012
Time: 10:45 AM