LOCKED UP: The role of biotic and abiotic interactions in the stabilisation and persistence of soil organic carbon

锁定：生物和非生物相互作用在土壤有机碳稳定和持久性中的作用

• 批准号: NE/S005137/1
• 负责人: Jeanette Whitaker
• 金额: $ 87.92万
• 依托单位: NERC CEH (Up to 30.11.2019)
• 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: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FS005137%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流失是21世纪最紧迫的环境挑战之一。有机碳的损失会导致气候变化，使土壤不太适合种植作物，通过氮（N）和磷（P）作为植物营养素的相关损失降低土壤肥力，并降低蓄水层的持水能力和排水能力-对抗旱和防洪，水质和水的可用性产生不利影响。“千分之四”国际倡议旨在解决SOC损失对粮食安全、气候调节和水资源的威胁，并旨在通过持续、渐进（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土壤中SOC产生和持久性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库存的能力和时间尺度。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的一系列复杂但可检验的相互作用产生的：1）相对快速的植物生物量输入土壤的微生物转化，产生; 2）特定类别的SOC化合物，包括细胞外产物和死细胞的组分，它们是持久形式的必要前体，然后3）通过对土壤矿物质的化学吸附而稳定以防止微生物降解，这可以从微生物可接近的C库中去除SOC;和4）通过土壤颗粒和土壤有机物的聚集而物理保护免受微生物降解，其中SOC在颗粒间和颗粒内孔隙空间中被保护免于微生物降解。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的基本知识，微生物的运作及其将SOC转化为与矿物质和矿物质聚集体持续存在的形式的速率;并量化这些转化和持续存在的形式如何响应不断变化的环境因素-植物输入C：氮比，水分胁迫，土著微生物群落组成，氧化还原状态，离子组成和孔隙沃茨的营养状况，温度和物理干扰。形成持久性有机碳的复杂和相互作用的阶段将被量化的阶段，在模型系统的微生物培养，水介质和选定的矿物在建成和真实的土壤基质，作为一个理想化的和实验上易于处理的土壤环境的代表。在多因素实验中，考虑到环境条件的范围，我们将量化速率定律和常数SOC转换的基础上的质量平衡，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则。研究结果将应用到现有的土壤过程模型中。这种机械知识的进步将使我们能够建立模型模拟从一个强大的第一原理的SOC转化动力学的理解，并导致土壤结构和散装性能的变化。我们将测试这些进步对独立的数据从操作实验的整个土壤芯从农业网站。将应用土壤机械过程模型，对从选定的土壤类型和生物群落中获得的、反映世界各地具体区域和土地利用情况的其他土芯进行处理。实验和模型结果将用于评估-针对关键土壤类型、气候区域和土地利用-可从假设的土地利用做法中获得的潜在最大值、时间尺度和持久性，以增加持久性有机碳的储存-例如，通过改变耕作做法、植被覆盖和水管理。

项目成果

Agricultural lands key to mitigation and adaptation-Response

农业用地是减缓和适应的关键-响应

• DOI: 10.1126/science.aba7577
• 发表时间: 2020
• 期刊: Science
• 影响因子: 56.9
• 作者: Morecroft M