CAREER: Mechanisms and control of nitrous oxide emissions from forage conservation

农业是美国的主要产业，2019年为美国国内生产总值（GDP）贡献了约1万亿美元。农业也是全球温室气体排放的重要贡献者。它是一氧化二氮（N2O）的最大来源，N2O是一种温室气体，其加热大气的效力大约是二氧化碳的300倍。然而，目前来自农业和农业经营的一氧化二氮排放清单，包括ISO 14064和USEPA美国温室气体排放和汇清单，只跟踪土壤管理、粪肥管理和农业残留物的田间燃烧排放。这个CAREER项目将重点关注饲料保护的一氧化二氮排放，这是农业和农业中一氧化二氮的丰富来源，但尚未被计算在内。牧草是作为牲畜饲料的植物或植物的一部分。饲料的保存通常依赖于发酵，因为发酵产生的乳酸是饲料作物的天然防腐剂。然而，产生温室气体的微生物也可以在保存的牧草中茁壮成长，这个CAREER项目的首席研究员（PI）的初步研究表明，苜蓿（一种广泛用于饲料保存的作物）的实验室孵育产生了大量的一氧化二氮。在这些初步研究结果的基础上，这个CAREER项目的PI建议开展一个综合的实验室和实地研究计划，以量化饲料保护中的一氧化二氮排放，并调查控制这种排放的微生物过程。该项目的成功完成将通过产生新的数据和基础知识来量化、管理和减轻非二氧化碳和更强的温室气体（如一氧化二氮）的排放，从而造福社会。进一步的社会效益将通过学生教育和培训来实现，包括指导堪萨斯州立大学的两名研究生和两名本科生。在农业和耕作中，饲料保护是一种重要的、未被充分研究的强效温室气体（如氧化亚氮（N2O））的来源。这个CAREER项目的总体目标是量化和推进对饲料保护过程中N2O排放机制的基本理解。该项目的实验室和实地研究的具体目标是：(1)量化和探索牧草保护区微生物排放N2O的机制（目标1），(2)制定控制和管理牧草保护区N2O排放的新策略（目标2），以及(3)在野外规模实验中验证实验室实验的发现（目标3）。这项研究的成功完成具有变革性影响的潜力。综合实验室和田间试验有助于在地方、区域和全球尺度上更准确地估计牧草保护带来的N2O通量。微生物学研究可以产生新的基础知识，并为制定更有效的策略和解决方案来管理和减少饲料保护过程中N2O的排放开辟新的途径。为了推进该CAREER项目的教育和培训目标，PI将与K-State研究与推广机构（堪萨斯州立大学农业实验站和合作推广服务机构）合作，通过外联和教育活动，提高畜牧业生产者对饲料保护产生的温室气体对环境影响的认识。此外，PI计划1)与美国未来农民协会（FFA）合作，为在堪萨斯州农村地区开展FFA项目的高中教师开发一个关于温室气体排放和农业和畜牧业管理的课程模块；2)与K-State项目影响的工作人员合作，鼓励和招募农村学生攻读环境工程的研究生教育。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Agriculture is a major industry in the United States contributing about $1 trillion to the Nation’s gross domestic product (GDP) in 2019. Agriculture is also a significant contributor to the global emissions of greenhouse gases (GHGs). It is the largest source of nitrous oxide (N2O), a GHG which is about 300 times as potent as CO2 at heating the atmosphere. However, the current N2O emission inventories from agriculture and farming operations, including ISO 14064 and USEPA Inventory of US Greenhouse Gas Emissions and Sinks, only track emissions from soil management, manure management, and field burning of agricultural residues. This CAREER project will focus on N2O emissions from forage conservations as an abundant and yet unaccounted source of N2O from agriculture and farming. Forages are plants or parts of plants that serve as feed for livestock. Forage conservation often relies on fermentation as lactic acid produced from fermentation works as a natural preservative for forage crops. However, microorganisms that produce GHGs can also thrive in conserved forages with preliminary studies by the Principal Investigator (PI) of this CAREER project showing the production of a significant amount of N2O from laboratory incubations of alfalfa, a widely used crop in forage conservation. Building upon the results of these preliminary studies, the PI of this CAREER project proposes to carry out an integrated laboratory and field research program to quantify N2O emissions in forage conservations and investigate the microbial processes that control such emissions. The successful completion of this project will benefit society through the generation of new data and fundamental knowledge to quantify, manage, and mitigate the emissions of a non-CO2 and more potent GHG such as N2O. Further benefits to society will be achieved through student education and training including the mentoring of two graduate students and two undergraduate students at Kansas State University.Forage conservation is a significant and understudied source of potent GHGs such as nitrous oxide (N2O) in agriculture and farming. The overarching goal of this CAREER project is to quantify and advance the fundamental understanding of the mechanisms of N2O emissions from forage conservation processes. The specific objectives of the project laboratory and field studies are to: (1) Quantify and probe the mechanisms of N2O emissions by microorganisms in forage conservations (Objective 1), (2) Develop new strategies to control and manage N2O emissions from forage conservations (Objective 2), and (3) Validate the findings from the lab experiments in field-scale experiments (Objective 3). The successful completion of this research has the potential for transformative impact. The integrated laboratory and field experiments could contribute to more accurate estimates of N2O fluxes from forage conservations at local, regional, and global scales. The microbiological investigations could produce new fundamental knowledge and open new avenues to develop more effective strategies and solutions to manage and mitigate N2O emissions from forage conservation processes. To advance the education and training goals of this CAREER project, the PI will work with K-State Research and Extension (the Kansas State University Agricultural Experiment Station and Cooperative Extension Service) to raise awareness of the environmental impact of GHGs produced from forage conservations among livestock producers through outreach and educational activities. In addition, the PI plans to 1) partner with Future Farmers of America (FFA) to develop a course module on GHG gas emissions and management in farming and livestock production for high school teachers who run FFA programs in rural Kansas and 2) work with the K-State Project Impact staff to encourage and recruit rural students to pursue graduate education in Environmental Engineering.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.