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.

通过人类土地使用失去土壤有机碳（SOC）是21世纪最紧迫的环境挑战之一。 SOC损失会导致气候变化，使土壤不适合农作物，通过氮（N）的损失（N）和作为植物营养素的磷（P）降低土壤的生育能力，并降低了对含水层的水位和排水，从而对干旱产生了不利影响和泛滥，耐水性，耐水性，水质和水质的可用性。国际倡议“每米4”旨在解决SOC损失对粮食安全，气候监管和水资源的威胁，并旨在通过持续的增量（例如每年0.4％）的增长来逆转全球SOC损失。我们的研究项目旨在改变对土壤中SOC生产和持久性的过程和机制的基本知识，以告知土地管理创新，并量化增加持久性的能力和时间尺度 - 即“锁定” - SOC股票。我们的假设是，持续的SOC是由土壤微生物和土壤矿物质之间的一系列复杂但可检验的相互作用产生的：1）植物生物量输入到土壤的微生物相对较快的微生物转化，这会产生； 2）特定类别的SOC化合物，包括细胞外产物和死细胞的成分，这些细胞是持续形式的必不可少的前体，然后是3）通过化学吸附到土壤矿物质的微生物降解，可以从微生物可访问的C池中清除SOC； 4）通过聚集土壤颗粒和土壤有机物，在物理保护中免于微生物降解，在该土壤颗粒和土壤有机物中，SOC免受了间和颗粒内孔隙空间的微生物降解。我们的方法是进行关联的实验室研究，现场抽样和建模，以获得土壤微生物关键功能群，微生物操作及其速率的基本知识，这些知识将SOC转化为形式，然后将其持续使用矿物质和矿物聚集体。并量化这些转化和持续形式如何应对不断变化的环境因素 - 植物输入C：N比，水应力，土著微生物群落组成，氧化还原状态，离子成分和孔隙水的营养状态，温度和身体障碍。形成持久性SOC的复杂和互动阶段将在阶段，在微生物培养物，水性培养基的模型系统中进行量化，并在建筑和真实的土壤矩阵中，作为土壤环境的理想化且可以实验可触及的矿物质。在解释环境条件范围的多因素实验中，我们将根据质量平衡，生物学生长，化学质量作用和物理化学胶体相互作用的第一原理来量化速率定律和常数。结果将被实施到现有的土壤过程模型中。机械知识中的这一进步将使我们能够从对SOC转化动态的强有力的第一原则中构建模型模拟，并导致土壤结构和块状特性的变化。我们将对来自农业场所的整个土壤核心的操纵实验的独立数据进行测试。通过应用机械土壤过程模型的应用，将对来自选定的土壤类型和生物群落的其他土壤核心操纵 - 以反映世界各地的特定区域和土地用途。实验和模型结果将用于评估 - 对于主要土壤类型，气候区域和土地用途 - 可以从假设的土地使用实践中获得的SOC的潜在最大时间，时间尺度和持久性，以增加持续的SOC库存 - 例如通过改变耕作习惯，植被覆盖和水管理。