Effect of vertical and lateral variations of soil moisture at the field-scale on root water uptake and plant transpiration
Research Area:
Soil Physics, Hydrology, Plant Sciences
Root water uptake plays an important role in the soil water balance and for land surface-atmosphere interactions. In this project, we simulate root water uptake from soil with a three-dimensional and dynamic model, R-SWMS, which couples water flow in the soil with root water uptake and flow inside the root system. This model has been extended to include the effect of hormonal signaling on transpiration and root water uptake, as well as the effect of soil environmental conditions on root development. In addition to the model development, a field rhizotron facility that allows a quasi-non-invasive monitoring of root growth and root zone processes at the field plot scale has been developed. The horizontal installation of 7-m long rhizotubes, which serve as access tubes for minirhizotron cameras, GPR antennas and NMR slimline tool, with minimal invasion so as to preserve the natural soil structure of the sub soil, was a challenge that required specialized technical solutions. Since rhizotron facilities of this extent and in undisturbed field plots have not been constructed before, specialized equipment had to be developed and tested.
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TR 32 Retreat 2017 in Schleiden
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Based on observations from the rhizotron facility and on simulations of coupled flow processes in the soil-root system, a macroscopic model for root water uptake was developed and is currently being implemented in the land surface model CLM. It is currently further developed for vegetation with different degrees of lateral root density heterogeneity and different degrees of hormonal control of transpiration. As the rhizotron facility allows mapping the spatial and temporal distribution of root development and water distribution, root development models can be parameterized from these data. The relation between root development and soil conditions such as water content/availability can be derived. Furthermore, it will be investigated if functional relations between root water uptake, root distribution, root development and soil water content distribution can be derived from plant and soil variables that can be monitored at a larger spatial scale and be included in the vegetation model CLM.
Cooperation partner:
