Modeling Root Water Uptake in Heterogeneous Soils.

Non uniform water distribution in soil and heterogeneous soil properties affect plant root water uptake. Beyond the total soil water storage, the spatial distribution of soil water and its availability to plants can also play a major role in plant transpiration. In addition, plant-specific properties like root system hydraulic architecture or sensitivity to chemical/hydraulic signaling also affect plant ability to transpire in heterogeneous environments. In this talk, we will first illustrate how soil and plant properties impact plant water uptake.  Then, we will use numerical simulations with a 3-D detailed soil-root model to quantify the relative impact of soil and plant processes on transpiration in heterogeneous soils.  We will show how novel simple models can be used to account for the impact of soil heterogeneity on plant water uptake and transpiration.  Finally we will present the current challenges and remaining knowledge gaps for simulating root water uptake in natural soils.