LOCKED UP: The role of biotic and abiotic interactions in the stabilisation and persistence of SOC

锁定：生物和非生物相互作用在 SOC 稳定和持久性中的作用

• 批准号: NE/S005153/1
• 负责人: Nicholas Ostle
• 金额: $ 41.21万
• 依托单位: Lancaster University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FS005153%2F1
• 关键词: LOCKED; UP; role; biotic; abiotic

Loss of soil organic carbon (SOC) through human land use is one of the most pressing environmental challenges of the 21st century. SOC loss contributes to climate change, makes soils less suitable for crops, reduces soil fertility through associated loss of nitrogen (N) and phosphorous (P) as plant nutrients, and reduces water holding capacity and drainage to aquifers - adversely impacting drought and flood resistance, water quality and water availability. The international initiative "4 per mille" addresses the threat of SOC loss to food security, climate regulation and water resources and aims to reverse global SOC losses through sustained, incremental (e.g. 0.4 % per year) increases. Our research project aims to transform fundamental knowledge of the processes and mechanisms of SOC production and persistence in soil to inform land management innovation, and quantify the capacity and time scale to increase persistent - i.e. "LOCKED UP" - SOC stocks. Our hypothesis is that persistent SOC is produced by a series of complex but testable interactions between soil microbes and soil minerals: 1) relatively rapid microbial transformation of plant biomass input to soil, which produces; 2) specific classes of SOC compounds including extracellular products and components of dead cells that are essential precursors to persistent forms, which are then 3) stabilised against microbial degradation through chemical sorption to soil minerals, which can remove SOC from the microbially accessible C pool; and 4) physically protected against microbial degradation through aggregation of soil particles and soil organic matter, where SOC is protected from microbial degradation in inter and intraparticle pore spaces. Our approach is to undertake linked laboratory studies, field sampling and modelling to obtain fundamental knowledge of key functional groups of soil microbes, the microbial operations and their rates which transform SOC to forms which then persist with minerals and within mineral aggregates; and to quantify how these transformations and persistent forms respond to changing environmental factors - plant input C:N ratios, water stress, indigenous microbial community composition, redox status, ionic composition and nutrient status of pore waters, temperature, and physical disturbance. The complex and interactive stages of forming persistent SOC will be quantified in stages, in model systems of microbial cultures, aqueous media and selected minerals in built and real soil matrices, as an idealised and experimentally tractable representation of the soil environment. In multi-factorial experiments that account for the range of environmental conditions, we will quantify rate laws and constants for SOC transformations based on first principles of mass balance, biological growth, chemical mass action and physical-chemical colloid interactions. The results will be implemented into an existing soil process model. This advance in mechanistic knowledge will allow us to build model simulations from a strong first principles understanding of the SOC transformation dynamics and resulting changes in soil structure and bulk properties. We will test these advances against independent data from manipulation experiments on whole soil cores from agricultural sites. Manipulation of additional soil cores - obtained from selected soil types and biomes to reflect specific regions and land uses around the world - will be carried out with application of the mechanistic soil process model. The experimental and model results will be used to assess - for key soil types, climate regions and land uses - the potential maximum, time scale and persistence of SOC that can be obtained from hypothesised land-use practices to increase stocks of persistent SOC - e.g. by changing tillage practices, vegetation cover and water management.

人类土地利用造成的土壤有机碳 (SOC) 损失是 21 世纪最紧迫的环境挑战之一。 SOC 损失会导致气候变化，使土壤不太适合农作物生长，通过作为植物养分的氮 (N) 和磷 (P) 的相关损失而降低土壤肥力，并降低持水能力和含水层的排水能力 - 对抗旱和抗洪能力产生不利影响、水质和水的可用性。国际倡议“千分之四”解决了 SOC 损失对粮食安全、气候调节和水资源的威胁，旨在通过持续增量（例如每年 0.4%）的增加来扭转全球 SOC 损失。我们的研究项目旨在转变有关 SOC 产生和土壤持久性的过程和机制的基础知识，为土地管理创新提供信息，并量化增加持久性（即“锁定”）SOC 储量的能力和时间尺度。我们的假设是，持久性 SOC 是由土壤微生物和土壤矿物质之间一系列复杂但可测试的相互作用产生的：1）输入土壤的植物生物量相对快速的微生物转化，产生； 2) 特定类别的 SOC 化合物，包括细胞外产物和死亡细胞的成分，它们是持久形式的重要前体，然后 3) 通过对土壤矿物质的化学吸附来稳定微生物降解，这可以从微生物可接触的碳库中去除 SOC； 4) 通过土壤颗粒和土壤有机质的聚集，以物理方式防止微生物降解，其中 SOC 在颗粒间和颗粒内孔隙空间中免受微生物降解。我们的方法是进行相关的实验室研究、现场采样和建模，以获得土壤微生物关键功能群、微生物运作及其将 SOC 转化为随后与矿物质和矿物团聚体一起存在的形式的速率的基础知识；并量化这些转化和持久形式如何响应不断变化的环境因素——植物输入碳氮比、水分胁迫、本土微生物群落组成、氧化还原状态、孔隙水的离子组成和营养状态、温度和物理干扰。形成持久性 SOC 的复杂和相互作用的阶段将在微生物培养、水介质和建筑和真实土壤基质中选定矿物质的模型系统中分阶段进行量化，作为土壤环境的理想化且可通过实验处理的表示。在考虑环境条件范围的多因素实验中，我们将根据质量平衡、生物生长、化学质量作用和物理化学胶体相互作用的第一原理量化 SOC 转化的速率定律和常数。结果将被应用到现有的土壤过程模型中。机械知识的进步将使我们能够根据对 SOC 转变动力学以及由此产生的土壤结构和整体特性变化的强大第一原理理解来构建模型模拟。我们将根据来自农业​​场地整个土壤核心的操纵实验的独立数据来测试这些进展。将从选定的土壤类型和生物群落中获得的额外土壤核心进行操作，以反映世界各地的特定区域和土地利用情况，将通过应用机械土壤过程模型来进行。实验和模型结果将用于评估 - 对于关键土壤类型、气候区域和土地利用 - SOC 的潜在最大值、时间尺度和持久性，可以从假设的土地利用实践中获得，以增加持久性 SOC 的储量 - 例如，通过改变耕作方式、植被覆盖和水管理。