Linking microbial biodiversity and ecosystem function in agricultural soils

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This project will assess the impact of agricultural management practices on the ecology and function of soil microorganisms. Recently the Canadian government has targeted increased renewable fuel production as a way to combat the country's dependence on fossil fuels. The increased demand for fuel feedstock has challenged the agricultural sector to provide agricultural crops for food, animal grain, as well as biofuels. Any management practice that alters microbial community structure is a concern because of the potential impact that it could have on plant growth and soil health, and long term soil ecosystem sustainability. In addition, alterations in activity and biodiversity of these microorganisms may have a cascading impact throughout the soil food web, since bacteria and fungi are known to be at its base. It may be possible that certain soil types or climatic regions may be better suited for long term agricultural production of biofuels, however, it is understood that the interaction between soil, plants and climate will influence the composition of the microbial community. Therefore it is important to begin to understand how spatial and temporal variability influences soil microbial community dynamics. This project will use quantitative PCR to assess the impact of plant species and biomass removal on the soil microbial community abundance and activity. We will target groups associated with C and N cycles including ammonia oxidizing bacteria (AOB), ammonia oxidizing archaea (AOA), denitrifying bacteria, free-living nitrogen fixers, cellulolytic bacteria as well as total bacteria and fungi. Furthermore, we will use a targeted metagenomics and metranscriptomics approach to examine the diversity of functional groups of microbes in these systems. Finally, DNA-stable isotope probing combined with metagenomics will be used to identify microorganisms that are associated with residues from bioenergy crops such as switchgrass and miscanthus. Increasing our understanding of microbial community dynamics may be invaluable to current efforts that are underway to improve models that predict the emission of N2O in agricultural fields, and to predict which soil and climatic regions can most easily sustain biomass removal for biofuel production while maintaining soil health and ecosystem sustainability. This knowledge will ultimately contribute to the development of strategies to combat climate change.