During photosynthesis, plants inevitably lose water that has to be continuously replaced by soil water absorbed by the roots. Hydrological status of the soil, root absorption, plant water transport, gas exchange and atmosphere are therefore intricately coupled within the soil–plant–atmosphere continuum (SPAC). It appears therefore straightforward to derive information on hydrology or plant ecophysiology from models that include as many components of the SPAC as possible. For example, plant related parameters might indicate the state of soil parameters. In this contribution, a basic model system is introduced that describes soil related parameters as dependent on plant parameters that are species-specific or have to be measured on-site: transpiration rate, leaf area index, root area index, ground area that is covered by the plant canopy, xylem conductivity, and leaf water potential. Test of the model indicates that plant subsurface parameters have no great influence on the model behavior. It appears feasible to obtain basic information on soil parameters by plant physiological parameters that can be readily measured above ground. In this case the approach has to be applied to at least three species of a site.