Water as medium for nutrient distribution: Monitoring water distribution between subsoil and topsoil considering roles of biopores and plants, by MRT and pressure probes (WatMed)

用于CeMiX的微型土芯(直径200 mm)的磁共振层析成像(MRT)由来自CeFiT的自然堆积的底土和表土组成，将在一个横向开放的1.5T磁体上进行，最终面内空间分辨率为200μm。核磁共振成像将以非侵入性的方式确定岩心内生物孔的三维分布及其形成的动力学，并与补充SP2的CT分析进行比较。一个主要目标是基于核磁共振弛豫参数，非侵入性地区分生物孔为蚯蚓和根系起源的生物孔，以及目前充满空气、水、根和蚯蚓的生物孔。此外，还将尝试根据生物孔的亲水性对不同的壁涂层进行分类。从CeFiT(SP 3)的初始值开始，将以5毫米的面内分辨率记录微宇宙核心及其生物孔结构内的水分布动态，同时测量用于计算生物量和根表面积的根生长动力学。将特别强调植物根系在不同土层之间重新分配水/D2O(和溶质)的作用。最后，我们将尝试从微观世界岩芯收集MRT控制的样本，与我们的SPS 4-8研究单位合作伙伴一起，重复访问最小侵入性获取的营养和微生物分布数据，以及非侵入性收集的水和根分布数据，作为SP 10中水和溶质循环的动态建模的基础。除了微观世界岩心，SP 3中使用的平板根管将用于使用压力探头测量根和地上部的静水压力分布，以及MRT测量。这样，水的分布和相应的驱动力以及生长动力将以最小的侵入性方式一起被测量。

Magnetic resonance tomography (MRT) on microcosm soil cores (200 mm Ø) used for CeMiX, comprising naturally stacked subsoil down to 700 mm plus topsoil from CeFiT, will be implemented at a laterally partially open Split 1.5 T magnet, with intended final in-plane spatial resolution of 200 μm. Three-dimensional biopore distributions and dynamics of their formation within the cores will be determined non-invasively and compared to complementing CT analyses of SP 2. One major aim is a non-invasive differentiation of the biopores into earthworm- and root system-originating ones and currently air-, water-, root- and earthwormfilled ones, based on NMR relaxation parameters. Attempts will additionally be made to classify different wall coatings of the biopores with regard to their water affinity. Dynamics of water distribution within the microcosm core and its biopore structures, starting from initial values taken from CeFiT (SP 3), will be documented with an in-plane resolution of 5 mm, in parallel to measurements of root growth dynamics for calculation of biomass and root surface area. Special emphasis will be put on the role of the plant root system for a re-distribution of water/D2O (and solutes) between different soil layers. Finally we will attempt MRT-controlled sample collection from the microcosm cores, to get – together with our research unit partners of SPs 4-8 – repeated access to minimally invasively acquired data on nutrient and microorganism distributions in concert with non-invasively collected water and root distribution data as a basis for dynamic modelling of water and solute circuits in SP 10. Beside the microcosm cores, flat rhizotrons as used in SP 3 will be employed to enable measurements of root and shoot hydrostatic pressure profiles with pressure probes, in addition to MRT measurements. In this way water distributions and corresponding driving forces and growth dynamics will be measured altogether in a minimally invasive manner.