The legacy of rhizosphere: how multi-year root activity fosters soil structure formation and the buildup of soil organic matter

在PP 2089“根际时空组织”的背景下，该项目的目的是调查根际时空发展对土壤结构的长期(遗留)影响以及根和土壤衍生有机物质的命运。我们将阐明植物根系活力和有机质输入与土壤结构之间的复杂联系，土壤结构受土壤质地和根系特征的调节。这项工作将从单一的根到根系统，从微米到地块尺度，整合定量和定性的方法。我们在联合实验室实验中涵盖了单一的根，以及完整的根系及其在田间的长期命运。一个主要的焦点将是阐明根源有机质在不同的根际土壤结构中的持久性，即由于根系活动而形成的土壤微团聚体和大团聚体。这些方法将基于对储存的碳池和氮池的定量和定性分析。在田间尺度上，我们将决定根际驱动土壤结构形成的长期命运和根源有机质的持久性。我们将测量不同土壤有机质组分以及不同土壤团聚体粒级的C、N含量和有机质的化学成分。根源有机质在不同团聚体大小等级中的持久性将通过实验室规模的培养实验来分析。我们将利用13C和15N同位素标记来追踪根部沉积物进入根部直接附近的微生物细胞和土壤隔间的命运。与其他几个PP参与者合作的综合方法将使人们能够从根本上洞察受根系影响的土壤性质的长期发展及其随时间的持久性，同时将为根际土壤集合体建模提供数据。根据这些结果，我们将对PP的焦点主题IV：固碳/微团聚体的形成/土壤结构的稳定性做出重要贡献。

The aim of the project in the context of the PP 2089 “rhizosphere spatiotemporal organisation” is to investigate the long term (legacy) effects of rhizosphere spatiotemporal development on soil structure and the fate of both root and soil derived organic matter. We will elucidate the intricate connection of plant root activity and organic matter input with the soil structure as modulated by soil texture and root traits. The work will reach from the single root up to the root system, integrating quantitative and qualitative approaches from micrometre to plot scale. We cover single roots in joint lab experiments as well as complete root systems and their long term fate in the field. A major focus will be the elucidation of the persistence of root derived organic matter in distinct rhizosphere soil structures, namely soil micro- and macroaggregates formed due to root activity. These approaches will be based on quantitative and qualitative analyses of the stored C and N pools. At field scale we will determine the long term fate of rhizosphere driven soil structure formation and the persistence of root derived organic matter. We will measure the amounts of C and N and the chemical composition of organic matter in different soil organic matter fractions as well as in distinct soil aggregate size fractions. The persistence of the root derived organic matter in distinct aggregate size classes will be analysed by laboratory scale incubation experiments. We will make use of 13C and 15N isotopic labelling to trace the fate of rhizodeposits into microbial cells and soil compartments in the direct vicinity of the root. The combined approach in collaboration with several other PP participants will allow to provide a fundamental insight into the long term development of root affected soil properties and their persistence over time and will at the same time provide data for modelling soil aggregation in the rhizosphere. With these results we will provide a significant contribution to focal topic iv ‘Carbon sequestration / microaggregate formation / stability of soil structure’ of the PP.