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和根和土壤来源的有机物质的命运的长期（遗产）影响。我们将阐明植物根系活性和有机质输入与土壤结构的复杂联系，土壤质地和根系性状的调制。这项工作将从单根到根系，从微米到小区尺度整合定量和定性方法。我们涵盖了联合实验室实验中的单根以及完整的根系及其在田间的长期命运。一个主要的重点将是阐明根源有机物在不同的根际土壤结构，即土壤微团聚体和大团聚体形成由于根系活动的持久性。这些方法将基于对储存的C和N库的定量和定性分析。在田间尺度上，我们将确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度组分中的C和N含量以及有机质的化学组成。将通过实验室规模的培养实验，分析不同聚集体大小类别的根源有机物的持久性。我们将利用13 C和15 N同位素标记追踪根沉积物进入根附近微生物细胞和土壤隔室的命运。与其他几个PP参与者合作的综合方法将允许提供对根影响土壤特性的长期发展及其随时间的持续性的基本见解，同时将提供用于模拟根际土壤聚集的数据。这些结果，我们将提供一个重要的贡献，重点课题四“碳封存/微团聚体的形成/土壤结构的稳定性”的PP。

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.