This title appears in the Scientific Report :
2014
High resolution modeling of water and nutrient uptake by plant roots: at a scale from single root to root system
High resolution modeling of water and nutrient uptake by plant roots: at a scale from single root to root system
The uptake of nutrients by plant roots is a multiscale problem. At the small scale, nutrient fluxes towards singleroots lead to strong gradients in nutrient concentrations around single roots. At the scale of the root system andsoil profile, nutrient fluxes are generated by water fluxes and variatio...
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Personal Name(s): | Abesha, Betiglu (Corresponding Author) |
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Vanderborght, Jan / Javaux, Mathieu / Schnepf, Andrea / Vereecken, Harry | |
Contributing Institute: |
Agrosphäre; IBG-3 |
Published in: | 2014 |
Imprint: |
2014
|
Conference: | General Assembly 2014- European Geoscience Union, Vienna (Austria), 2014-04-27 - 2014-05-02 |
Document Type: |
Poster |
Research Program: |
Terrestrial Systems: From Observation to Prediction Modelling and Monitoring Terrestrial Systems: Methods and Technologies |
Publikationsportal JuSER |
The uptake of nutrients by plant roots is a multiscale problem. At the small scale, nutrient fluxes towards singleroots lead to strong gradients in nutrient concentrations around single roots. At the scale of the root system andsoil profile, nutrient fluxes are generated by water fluxes and variations in nutrient uptake due to spatially varyingroot density, nutrient concentrations and water contents. In this contribution, we present a numerical simulationmodel that describes the processes at the scale of a single root and the scale of the entire root system simultaneously.Water flow and nutrient transport in the soil are described by the 3–D Richards and advection-dispersion equations,respectively. Water uptake by a root segment is simulated based on the difference between the soil water potentialat the soil root interface and in the xylem tissue. The xylem water potential is derived from solving a set of flowequations that describe flow in the root network (Javaux et al., 2008). Nutrient uptake by a segment is simulatedas a function of the nutrient concentration at the soil-root interface using a nonlinear Michaelis–Menten equation.An accurate description of the nutrient concentrations gradients around single roots requires a spatial resolutionin the sub mm scale and is therefore not feasible for simulations of the entire root system or soil profile. In orderto address this problem, a 1–D axisymmetric model (Barber and Cushman, 1981) was used to describe nutrienttransport towards a single root segment. The network of connected cylindrical models was coupled to a 3–D regulargrid that was used to solve the flow and transport equations at the root system scale. The coupling was done bymatching the fluxes across the interfaces of the voxels of the 3–D grid that contain root segments with the fluxesat the outer boundaries of the cylindrical domains and by matching the sink terms in these voxels with uptake bythe root segments. To demonstrate the feasibility of this method, we compared cumulative nutrient uptake by thecoupled (3D–1D) with results obtained at the single root scale using a high resolution model and the approximateanalytical solution of Roose et al., (2001). The good agreement between the fine mesh 3–D and a coupled (3D–1D)model makes this coupling approach capable to simulate a root system scale models without a high computationalcost. Furthermore, the coupling allows to account for the effect of water uptake and soil drying on nutrient uptakeand to account for spatial variations in root density and nutrient concentrations. These effects cannot be representedby a simple upscaling of single root scale models since they require the description of water and nutrient fluxeswithin the entire root zone. |