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，对全球气候变化有影响。一氧化二氮的浓度要低得多，但作为温室气体的威力比二氧化碳大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前途的减少N2O排放的方法的发展，该方法涉及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稷领域的N2O排放，并改善生物炭应用和氮肥下土壤N2O排放的预测。该项目的发现将有助于减少农田土壤中的N2O排放，维持柳枝稷的生产力，并可能减缓全球变暖。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。该项目的研究结果将纳入本科生和研究生的课程。该项目还将有助于提高一个为代表性不足的少数群体服务的机构的研究能力，并扩大代表性不足的群体对生态学和环境科学的参与，土壤N2O排放是通过硝化和反硝化过程产生的，并受到若干因素的影响，包括土壤温度、湿度、氮的供应、土壤微生物的组成和活动。在本研究中，我们将采用一种综合的方法，通过野外温室测量、实验室培养和生态系统模拟来量化土壤N2O排放的动态和机制。利用土壤酶活性和土壤微生物组成分析，评估不同生物炭和氮肥施用制度下土壤微生物种群在N2O排放中的作用。新的发现，从现场和实验室研究将被纳入一个生态地球化学模型，以改善土壤N2O排放估计。这项研究的结果将导致土壤N2O排放和土壤微生物对柳枝稷领域氮素可用性变化的反应的预测性和机械性理解。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

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.