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

二氧化碳(CO2)和一氧化二氮(N2O)等温室气体是大气中重要的吸热气体，有助于全球气候变化。一氧化二氮的存在浓度要低得多，但作为一种温室气体，其威力约为二氧化碳的300倍。大量施用氮肥的农田土壤是释放到大气中的N2O的主要来源。减少农田温室气体排放的努力导致了一种有希望的减少N2O排放的方法的开发，其中包括使用生物炭作为土壤改良剂。然而，生物炭和氮肥如何相互作用影响土壤N2O释放仍然是一个谜。这项卓越研究(EIR)奖将使研究人员能够调查柳枝花田地的N2O排放，并改进对生物炭施用和氮肥施肥下土壤N2O排放的预测。该项目的发现将有助于减少农田土壤N2O的排放，维持柳枝草的生产力，并有可能减缓全球变暖。两名研究生和六名本科生将直接参与该项目，并获得实践研究经验。这个项目的发现将被纳入本科生和研究生的课程。该项目还将有助于提高为代表不足的少数群体服务的机构的研究能力，并扩大代表不足的群体对生态和环境科学的参与。土壤N2O的排放是通过硝化和反硝化过程产生的，受土壤温度、水分、氮素有效性以及土壤微生物组成和活动等几个因素的影响。在这个项目中，将使用一种综合的方法来量化土壤N2O排放的动态和机制，方法包括野外小室测量、实验室培养和生态系统模拟。将通过土壤酶活性和土壤微生物组成分析来评估不同生物炭和氮肥制度下土壤微生物种群在N2O排放中的作用。来自田间和实验室研究的新发现将被纳入生物地球化学模型，以改善土壤N2O排放的估计。这项研究的结果将导致对土壤N2O排放和土壤微生物对柳枝草农田氮素有效性变化的响应的预测性和机械性的理解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.