Flow of Water Through Root‐Soil Environment

Abstract

A model is developed for simulating the vertical movement of water through a crop's root system. The root‐water flow model is then coupled to a variably‐ saturated flow model via a root extraction term that is a function of the water pressure gradient across the root‐soil interface as well as soil and root parameters. The resulting root‐soil water flow model is a coupled pair of partial differential equations that describe the macroscopic movement of water through a root‐soil system. Rainfall, irrigation, and evaporation are treated as sources of potential soilsurface flux, and transpiration is treated as a source of potential root‐surface flux. Solution of the model is accomplished by using a Galerkin finite element method. The model is verified by comparing simulated and field measured soil‐water content levels. The comparisons show a very good agreement between simulated and measured soil‐water contents. The root extraction distribution, cumulative flow from an underlying water table, and sensitivity of model results to changes in root parameters are also analyzed.