Collaborative Research on Nitrogen Cycling in Ecosystems under Elevated CO2 and O3 is Regulated by Soil Microbial Communities at the Microscale

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Atmsopheric carbon dioxide (CO2) concentration has increased by 31% during the past century, and atmospheric ozone (O3) concentration has risen about 1 percent per year over the past four decades. The combined influence of elevated CO2 and O3 on agriculture is direct but often unpredictable. Consequently, the goal is to investigate the relationships between changes in soybean productivity, microbial community composition and nitrogen cycling in response to elevated CO2 and O3. The focus will be on biological nitrogen fixation, a major nitrogen input process, and nitrification and denitrification, processes inducing nitrogen losses. These nitrogen cycling processes will be determined with stable isotope techniques and will be linked to the microbial community structure, which will be measured by molecular techniques. Although soil nitrogen availability is crucial for plant growth, the long-term effects of elevated CO2 and O3 on the capacity of the soil to sustain plant productivity is largely unknown. This project will bridge this knowledge gap by linking the structure and function of soil microbes to the flow of nitrogen. The results from this research will improve our overall understanding of the role soil processes play in maintaining sustainable ecosystem functioning under elevated CO2 and O3. This area of inquiry and education is important as increased human population and atmospheric pollution increasingly stress ecosystems.