The influence of trigger events on bursts of soil microbial metabolism and N2O production and consumption

触发事件对土壤微生物代谢爆发和N2O产生和消耗的影响

• 批准号: RGPIN-2015-03746
• 负责人: Burton, David
• 金额: $ 1.97万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=681978
• 关键词: influence; trigger; events; bursts; soil

Climate drives the biological processes occurring in soil yet is a poorly described and seldom considered part of nitrogen management in agriculture. This is due to the number and complexity of processes involved in the soil N cycle. In this proposal we examine the role of climatic triggers (thawing of frozen soil and wetting of dry soil) in stimulating bursts of microbial activity and causing soil N losses. Specifically this work focuses on the influence substrate availability on inorganic nitrogen processes that control the timing and relative importance of nitrification and denitrification in producing N2O emissions. My hypothesis is that environmental events trigger microbial metabolism through the release of substrates as a result of microbial cell-lysis and solubilization of soil organic matter. Further, it is the rate at which microbial metabolism acts on these substrates, as influenced by soil temperature and water content, and the architecture of carbon and nitrogen distribution which determines the location, intensity, and products of denitrification and therefore N2O emissions.***The goal of my research is to understand the impacts of climate and climate change on soil N transformations and nitrogen losses. The specific objective of this proposal is firstly (PhD1) to examine the mechanisms resulting in N2O bursts in response to thawing and wetting triggers under controlled environment conditions and secondly (PhD 2) to examine the production and consumption of N2O in soil profiles in response to thawing and wetting triggers under field conditions.***This research takes advantage of recent technological developments that allow high frequency measurement of the isotopomeric composition of N2O emissions to determine the source of N2O during trigger events. Measurements of N2O production will be coupled with continuous measurement of soil water and temperature to provide a dynamic picture of how the physical effects of trigger events are translated into shifts in microbial metabolism. ***This research is innovative in that it uses high frequency measurement of concentration and isotopomeric composition of N2O to study the nature of microbial metabolism associated with environmental events. The use of 15N site preference of N2O will distinguish between nitrification and denitrification as sources of N2O during these events as well as the consumption of N2O by denitrification. ***This research will provide insight into the potential impacts of climate change on soil microbial processes. A better understanding of how agricultural management impacts N2O emissions associated with thawing and wetting events. This is important for developing strategies to sustain soil fertility and reduce greenhouse gas emissions from agriculture, reduce impacts on water quality and increase the profitability and sustainability of agriculture.

气候驱动了土壤中发生的生物过程，但在农业氮素管理中，气候描述得很少，也很少被考虑。这是由于土壤氮素循环涉及的过程的数量和复杂性。在这项建议中，我们研究了气候触发因素(冻土融化和干土壤湿润)在刺激微生物活动爆发和造成土壤氮素损失方面的作用。具体地说，这项工作着重于基质利用率对无机氮过程的影响，这些过程控制着硝化和反硝化在产生N2O排放中的时机和相对重要性。我的假设是，环境事件通过释放底物来触发微生物新陈代谢，这是微生物细胞分解和土壤有机质溶解的结果。此外，微生物新陈代谢作用于这些基质的速度受土壤温度和水分的影响，以及碳和氮分布的结构，决定了反硝化的位置、强度和产物，从而决定了N2O的排放。*我的研究目的是了解气候和气候变化对土壤N转化和N损失的影响。这项建议的具体目标是首先(Phd1)研究在受控环境条件下响应融化和润湿触发而导致N2O爆发的机制，其次(Phd2)研究在田间条件下响应融化和润湿触发而在土壤剖面中N2O的产生和消耗。*这项研究利用最近的技术发展，允许高频测量N2O排放的同位素组成，以确定触发事件期间N2O的来源。N2O产量的测量将与土壤水分和温度的连续测量相结合，以提供触发事件的物理影响如何转化为微生物新陈代谢的变化的动态图景。*这项研究的创新之处在于，它使用对N2O浓度和同位素组成的高频测量来研究与环境事件相关的微生物代谢的性质。使用N2O的15N位偏好将区分硝化作用和反硝化作用作为这些事件期间N2O的来源，以及反硝化作用对N2O的消耗。*这项研究将深入了解气候变化对土壤微生物过程的潜在影响。更好地了解农业管理如何影响与融化和潮湿事件相关的N2O排放。这对于制定保持土壤肥力和减少农业温室气体排放、减少对水质的影响以及提高农业的盈利能力和可持续性的战略非常重要。