Uncertainty quantification for water and nutrient uptake simulation of an architectural root system

Plant-root-soil interplays have a crucial role in the development of the terrestrial system. Therefore, modelling of root-soil interactions has become an essential tool for studying physical biochemical processes in the root-soil system. However, the soil characteristics and root properties such as hydraulic parameters, nutrient buffer capacity in the soil are mostly uncertain due to lack of our knowledge. This contribution presents an uncertainty quantification study for nutrient uptake model of 3D architectural root system in a 3D soil. In a simple case of single root segment, the Monte Carlo (MC) method was used to investigate the nonlinearity of the root-soil system. The performance of the Taylor series approximation (TSA) and Polynomial Chaos Expansion (PCE) methods were also investigated. For a complex 3D root architecture system, the MC method becomes unfeasible due to high computational cost. In the other hand, the PCE method showed its exceptional performance with less number of simulation runs. Figure 1: Spatial distribution of most sensitive parameters to nitrate concentration in soil matrix and root system