Simple analytical model of evapotranspiration in the presence of roots.
Evaporation of water out of a soil involves complicated and well-debated mechanisms. When plant roots are added into the soil, water transfer between the soil and the outside environment is even more complicated. Indeed, plants provide an additional process of water transfer. Water is pumped by the roots, channeled to the leaf surface, and released into the surrounding air by a process called transpiration. Prediction of the evapotranspiration of water over time in the presence of roots helps keep track of the amount of water that remains in the soil. Using a controlled visual setup of a two-dimensional model soil consisting of monodisperse glass beads, we perform experiments on actual roots grown under different relative humidity conditions. We record the total water mass loss in the medium and the position of the evaporating front that forms within the medium. We then develop a simple analytical model that predicts the position of the evaporating front as a function of time as well as the total amount of water that is lost from the medium due to the combined effects of evaporation and transpiration. The model is based on fundamental principles of evaporation fluxes and includes empirical assumptions on the quantity of open stomata in the leaves, where water transpiration occurs. Comparison between the model and experimental results shows excellent prediction of the position of the evaporating front as well as the total mass loss from evapotranspiration in the presence of roots. The model also provides a way to predict the lifetime of a plant.
Complex Assemblies of Soft Matter, CNRS-Solvay-UPenn UMI 3254, Bristol, Pennsylvania 19007-3624, USA.
Cesare M
CM
Cejas
Complex Assemblies of Soft Matter, CNRS-Solvay-UPenn UMI 3254, Bristol, Pennsylvania 19007-3624, USA.
L A
LA
Hough
Solvay Research and Innovation Centre, Aubervilliers, France 93300.
Jean-Christophe
JC
Castaing
Physico-chimie des Polymères et des Milieux Dispersés CNRS PPMD UMR 7615 ESPCI, Paris, France 75005.
Christian
C
Frétigny
Complex Assemblies of Soft Matter, CNRS-Solvay-UPenn UMI 3254, Bristol, Pennsylvania 19007-3624, USA.
Rémi
R
Dreyfus
D004777:Environment; D006813:Humidity; D008962:Models, Theoretical; D018517:Plant Roots / Q000502:physiology*; D054046:Plant Stomata / Q000378:metabolism; D018526:Plant Transpiration / Q000502:physiology*; D012987:Soil; D014867:Water
D012987:Soil; D014867:Water