Excellence in Research: Dynamics and Controls of Nitrous Oxide Emission in Switchgrass Fields under Biochar Application and Nitrogen Fertilization

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Greenhouse gases such as carbon dioxide (CO2) and nitrous oxide (N2O) are important heat-trapping gases in the atmosphere, contributing to changes in global climate. Nitrous oxide is present at a much lower concentration but is about 300 times more powerful a greenhouse gas than CO2. Cropland soils that receive heavy application of nitrogen fertilizer are a major source of N2O released to the atmosphere. Efforts to reduce greenhouse gas emissions from croplands have led to the development of a promising method to reduce N2O emissions that involves the use of biochar as a soil amendment. However, how biochar and nitrogen fertilization interact to influence soil N2O release remains a mystery. This Excellence in Research (EiR) award will enable researchers to investigate N2O emissions in switchgrass fields and to improve prediction of soil N2O emission under biochar application and nitrogen fertilization. The findings from this project will help reduce soil N2O emissions in croplands, sustain the productivity of switchgrass, and potentially slow global warming. Two graduate students and six undergraduate students will participate directly in the project and gain hands-on research experience. Findings from this project will be incorporated into courses for undergraduate and graduate students. The project will also contribute to the improvement of research capacity at an institution serving underrepresented minorities and broaden the participation of under-represented groups in ecology and environmental sciences.Soil N2O emission is produced through nitrification and denitrification processes and influenced by several factors including soil temperature, moisture, nitrogen availability, and soil microbial composition and activities. In this project, an integrated approach will be used to quantify the dynamics and mechanisms of soil N2O emission using field chamber measurement, laboratory incubation, and ecosystem modeling. The role of soil microbial populations in N2O emission under different biochar and nitrogen fertilization regimes will be assessed using soil enzymatic activities as well as soil microbial composition analysis. The new findings from field and laboratory studies will be incorporated into a biogeochemical model to improve soil N2O emission estimation. Results of this study will lead to a predictive and mechanistic understanding of soil N2O emission and soil microbial responses to changes in nitrogen availability in switchgrass fields.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.