Evaluation of the relative importance to carbon sequestration and nutrient cycling of root exudation, and turnover of roots and mycorrhizas

评估根系分泌物对固碳和养分循环以及根系和菌根周转的相对重要性

• 批准号: 1645860
• 金额: --
• 依托单位: Bangor University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1645860
• 关键词: Evaluation; relative; importance; carbon; sequestration

Maintaining soil function and carbon storage represent key objectives in sustainable agriculture. Most C, N and P is returned to soil via exudation from live roots, and turnover of dead roots and their associated symbionts. Consequently, both the rate at which C fixed by plants is returned to the atmosphere as CO2 and the rate at which nutrients are recycled to plant-available forms are tightly coupled. However, quantitative separation of the three most important below-ground fluxes of C and nutrients (root exudation and root and mycorrhizal turnover) remains largely unachieved. This is due both to limited understanding of the fate of the range of C, N and P compounds and their polymers (e.g. protein, nucleic acids, cellulose, lignin and chitin) delivered to soil, and to a lack of suitable techniques to measure rates of delivery. Consequently, poor knowledge of these fluxes is a major impediment to understanding and modelling the storage of atmospheric C in soils and the factors controlling nutrient cycling. We propose to utilise recent technological advances to determine: (1) The relative quantities and types of C, N and P delivered to the soil in turnover of roots and mycorrhizas in temperate permanent grassland. (2) The rate and route of utilisation by soil microbes of the various forms of C delivered to the soil by these processes and how this controls the delivery of C back to the atmosphere as CO2. (3) How synchronous with mineralisation of plant C to CO2 is the return of N and P to plant-available forms. (4) How estimates of root and mycorrhizal turnover measured by state-of-the-art techniques compare with those from more traditional approaches.

保持土壤功能和碳储存是可持续农业的关键目标。大部分C、N和P通过活根的渗出和死根及其相关共生体的周转返回到土壤中。因此，植物固定的C以CO2形式返回大气的速率和营养物质再循环为植物可用形式的速率是紧密耦合的。然而，定量分离的三个最重要的地下通量的C和养分（根分泌物和根和菌根营业额）仍然在很大程度上没有实现。这是由于对C、N和P化合物及其聚合物（例如蛋白质、核酸、纤维素、木质素和几丁质）递送到土壤中的范围的命运的理解有限，以及缺乏测量递送速率的合适技术。因此，这些通量的知识不足是理解和模拟大气碳在土壤中的储存和控制养分循环的因素的一个主要障碍。本文拟利用最新的技术进展来确定：（1）温带永久性草地根系和菌根周转过程中向土壤输送的C、N、P的相对数量和类型。(2)土壤微生物对通过这些过程输送到土壤中的各种形式的C的利用率和途径，以及这如何控制C以CO2的形式返回大气。(3)与植物C矿化为CO2的同步程度是N和P返回到植物可利用的形式。(4)如何估计根和菌根周转率测量国家的最先进的技术与那些从更传统的方法比较。