Diurnal Variation in Soil Nitrous oxide Emissions (DIVINE): drivers and mechanisms

土壤一氧化二氮排放量的日变化（神圣）：驱动因素和机制

基本信息

批准号：
NE/V000837/1
负责人：
Niall McNamara
金额：
$ 52.44万
依托单位：
UK CENTRE FOR ECOLOGY & HYDROLOGY
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2021
资助国家：
英国
起止时间：
2021 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FV000837%2F1
关键词：
Diurnal Variation Soil Nitrous oxide

项目摘要

Nitrous oxide (N2O) is a potent greenhouse gas (GHG) with a global warming potential 298 times that of carbon dioxide. Agriculture contributes approximately two thirds of anthropogenic N2O emissions and is the most challenging sector for emissions reductions. Agriculture is also the largest source of uncertainty for national GHG reporting because N2O emissions are highly variable in space and time and consequently difficult to measure accurately.To achieve the enormous reductions urgently needed, we must be able to accurately measure and predict soil N2O emissions. Our work has demonstrated that N2O emissions can vary diurnally by up to 400% in agricultural soils. This diurnal variation is not captured in current measurements and predictions of N2O emissions. In DIVINE we will investigate for the first time, the mechanistic basis of diurnal variation in N2O emissions and use modelling approaches to quantify how this diurnal variation contributes to uncertainty in N2O emission factors used for GHG inventory reporting. Our aim is to enable more accurate GHG inventory reporting and more effective testing of mitigation strategies for agricultural N2O emissions. Our work has demonstrated that N2O emissions can vary diurnally in fertilised soils with emissions peaking in mid-afternoon. Soil N2O emissions are conventionally measured at a single time of day, leading to significant errors when measurements are scaled up to annual emission estimates. Whilst the existence of diurnal N2O variation is generally accepted, the underlying mechanisms are poorly understood. Greater daytime N2O emissions are typically attributed to increased microbial activity with increasing temperature. However, our recent research suggests light intensity is also important. We hypothesise that this is not a direct effect of light intensity, but rather differences in plant metabolism (photosynthesis and root exudation) between day and night altering soil properties (e.g. carbon availability and oxygen) and so promoting diurnal variation in N2O. It is only recently that we have been able to make these conclusions due to major technological advances that allow us to measure N2O emissions near-continuously from multiple locations over day-night cycles. Supported by this technology we will investigate the importance, drivers and mechanisms of diurnal N2O variation through four work packages. We will: 1. Conduct field experiments over whole crop life-cycles to quantify how diurnal N2O emissions vary with management practices and soil physical properties (WP1); 2. Construct outdoor mesocosms with soil temperature control and shading treatments to determine to what extent temperature and light intensity drive diurnal variations in N2O emissions (WP2). 3. Conduct laboratory experiments to identify the mechanisms by which plant metabolism affects soil nitrogen cycling and amplifies daytime N2O emissions (WP3)4. Quantify how diurnal variation in N2O emissions affects the accuracy of national GHG inventory reporting for agriculture and use Bayesian modelling to improve the accuracy of N2O emission factors by accounting for diurnal variability (WP4). The outcomes of the project will enable diurnal N2O variation to be factored into tools and models for reporting and predicting agricultural GHG emissions and will enable more accurate testing of agricultural N2O mitigation strategies.

一氧化二氮（N2O）是一种有效的温室气体（GHG），全球变暖潜力是二氧化碳的298倍。农业贡献了大约三分之二的人为N2O排放，并且是减少排放的最具挑战性的领域。农业也是国家温室气体报告的最大不确定性来源，因为N2O的排放在时空上是高度变化的，因此很难准确地测量。为了迫切需要实现巨大的减少，我们必须能够准确测量并预测N2O的N2O排放。我们的工作表明，在农业土壤中，N2O的排放量可能会在共同变化400％。在当前的测量和N2O排放的预测中未捕获这种昼夜变化。在神中，我们将首次调查N2O排放中昼夜变化的机理基础，并使用建模方法来量化这种昼夜变化如何导致用于GHG库存报告的N2O排放因子的不确定性。我们的目的是实现更准确的温室气库报告，并对农业N2O排放的缓解策略进行更有效的测试。我们的工作表明，N2O的排放可能在施肥的土壤中界定，午后排放峰值达到峰值。通常在一天中的一次时间中测量土壤N2O排放，当测量结果缩放到年度排放估计值时，导致明显的错误。尽管普遍接受昼夜N2O变异的存在，但对基本机制的理解很少。较大的白天N2O排放通常归因于随着温度升高的微生物活性的增加。但是，我们最近的研究表明光强度也很重要。我们假设这不是光强度的直接效应，而是昼夜改变植物代谢（光合作用和根源渗出）的差异，而昼夜改变了土壤特性（例如碳的可用性和氧气），从而促进N2O中的昼夜变化。直到最近，由于主要的技术进步，我们才能够得出这些结论，这使我们能够在昼夜周期中从多个位置近距离测量N2O的排放。在这项技术的支持下，我们将通过四个工作包进行调查昼夜N2O变化的重要性，驱动因素和机制。我们将：1。对整个农作物生命周期进行实地实验，以量化昼夜N2O排放如何随管理实践和土壤物理特性而变化（WP1）； 2。构建具有土壤温度控制和阴影处理的室外室内焦点，以确定N2O排放的温度和光强度驱动昼夜变化的程度（WP2）。 3。进行实验室实验，以确定植物代谢影响土壤氮循环并放大白天N2O排放的机制（WP3）4。量化N2O排放的昼夜变化如何影响农业的国家温室气体清单报告的准确性，并使用贝叶斯建模来通过考虑昼夜变化（WP4）来提高N2O排放因子的准确性。该项目的结果将使昼夜N2O变异能够纳入报告和预测农业温室气体排放的工具和模型，并能够对农业N2O缓解策略进行更准确的测试。