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.

气候驱动土壤中发生的生物过程，但对农业氮管理的描述很少，很少被认为是农业氮管理的一部分。这是由于土壤氮循环过程的数量和复杂性造成的。在本提案中，我们研究了气候触发因素（冻土解冻和干土湿润）在刺激微生物活动爆发和导致土壤氮流失中的作用。具体来说，这项工作重点关注底物可用性对控制硝化和反硝化在产生 N2O 排放中的时间和相对重要性的无机氮过程的影响。我的假设是，环境事件通过微生物细胞裂解和土壤有机质溶解而释放底物来触发微生物代谢。此外，微生物代谢作用于这些基质的速率（受土壤温度和含水量的影响）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 排放。***我研究的目标是了解气候和气候变化对土壤氮转化和氮损失的影响。该提案的具体目标首先是（PhD1）研究在受控环境条件下响应解冻和润湿触发而导致 N2O 爆发的机制，其次（PhD 2）研究土壤剖面中 N2O 的产生和消耗以响应现场条件下的解冻和润湿触发。***这项研究利用了最新的技术发展，允许高频测量 N2O 的同位素组成。 N2O 排放以确定触发事件期间 N2O 的来源。 N2O 产生的测量将与土壤水和温度的连续测量相结合，以提供触发事件的物理效应如何转化为微生物代谢变化的动态图景。 ***这项研究的创新之处在于它使用高频测量 N2O 的浓度和同位素异构体组成来研究与环境事件相关的微生物代谢的性质。使用 N2O 的 15N 位点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解冻和湿润事件相关的氧化亚氮排放。这对于制定维持土壤肥力、减少农业温室气体排放、减少对水质的影响以及提高农业盈利能力和可持续性的战略非常重要。