On a better understanding of hydraulic lift: A numerical study

Abstract

Hydraulic lift is the transport of water from moist into drier soil layers through plant root systems: Plant roots sometimes do not only take up water but also release water if the soil is dry. Hydraulic lift has been shown for a relatively small number of species, but it is believed to be a more general phenomenon. We model numerically water uptake and two‐dimensional water transport through the soil and through the root system as coupled processes. Both water uptake and transport through the root system are considered to be hydraulic processes; osmotic effects are neglected. The model is capable of tracing hydraulic lift; the simulated amount of shifted water is consistent with experimental data. This supports the theory that hydraulic lift is a pure hydraulic process without an osmotic component. Furthermore, we discuss how far hydraulic lift could be an optimized strategy for the plant.