Greenhouse Gas Fluxes in Agroecosystems: Towards an Integrated Understanding on Source-Processes and Spatio-Temporal Variation

农业生态系统中的温室气体通量：对源过程和时空变化的综合理解

• 批准号: RGPIN-2018-05717
• 负责人: HernandezRamirez, Guillermo
• 金额: $ 4.37万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=764524
• 关键词: Greenhouse; Gas; Fluxes; Agroecosystems; Towards

Greenhouse gas emissions derived from land-use systems are significant contributors (14%) to climate change, with croplands accounting for two-thirds of these emissions. Greenhouse gas emissions result from biophysical processes driven by soil temperature, oxygen concentration, and water content as well as the availability of nitrogen and carbon substrates for microbial activity. Processes such as denitrification and nitrification generate nitrous oxide, while plant root growth and microbial respirations produce carbon dioxide. The complexity of these processes results in large variability of greenhouse gas emissions both in space and time. Moreover, the additions of nitrogen from fertilizers and manure, and carbon from plant roots further increase this complexity. Collectively, these interacting factors lead to significant uncertainties in the quantification of greenhouse gas fluxes and sources across the landscape.My long-term research objective is to understand the triggers and drivers of nitrous oxide and carbon dioxide generation in soils. This knowledge is critical for identifying effective emission reduction options in Canadian agroecosystems, hence contributing to climate change mitigation.To achieve this objective, the proposed research will:1. Distinguish and quantify nitrous oxide that is produced through nitrification versus denitrification processes in soils, and investigate which process is the main flux source following nitrogen additions such as manure and fertilizer.2. Differentiate between sources of carbon dioxide from soils (organic matter breakdown versus root-derived respiration), and identify the effects of root growth on both carbon dioxide flux and turnover of organic matter across gradients of root carbon environments.3. Quantify the response of nitrous oxide and carbon dioxide production resulting from cyclic fluctuations of soil oxygen concentration, wetting-drying, and temperature.4. Use this gained understanding to identify causes and explain spatio-temporal variations in field fluxes with focus on peak emissions within varying field topography.In the next 5 years, I will train two MSc, two PhD, and four undergraduate students throughout this program. This research will create critical scientific foundations for improved management of greenhouse gas emissions, and support innovative strategies for emission reductions that are adaptable to Canadian agroecosystems under a changing environment.

来自土地使用系统的温室气体排放是气候变化的重要贡献者（14%），其中农田占这些排放量的三分之二。温室气体排放是由土壤温度、氧浓度和含水量以及微生物活动所需的氮和碳基质的可用性所驱动的生物物理过程造成的。反硝化和硝化等过程产生一氧化二氮，而植物根系生长和微生物呼吸产生二氧化碳。这些过程的复杂性导致温室气体排放在空间和时间上的巨大变化。此外，来自肥料和粪肥的氮以及来自植物根部的碳的增加进一步增加了这种复杂性。总的来说，这些相互作用的因素导致温室气体通量和整个景观来源的量化存在很大的不确定性。我的长期研究目标是了解土壤中一氧化二氮和二氧化碳生成的触发因素和驱动因素。这些知识对于确定加拿大农业生态系统中有效的减排方案至关重要，从而有助于减缓气候变化。区分和量化土壤中通过硝化和反硝化过程产生的氧化亚氮，并调查哪个过程是氮添加（如粪肥和化肥）后的主要通量来源.区分土壤中二氧化碳的来源（有机质分解与根源呼吸），并确定根系生长对二氧化碳通量和根系碳环境梯度中有机质周转的影响。3.量化土壤氧浓度、干湿和温度周期波动对氧化亚氮和二氧化碳产生的响应.利用这一理解来确定原因，并解释场通量的时空变化，重点是不同场地形内的峰值发射。在未来5年内，我将在整个项目中培养两名硕士，两名博士和四名本科生。这项研究将为改善温室气体排放管理奠定重要的科学基础，并支持在不断变化的环境下适应加拿大农业生态系统的减排创新战略。