I have a model (Miguez et al 2008) that defines wilting point as the soil water content below which there is no transpiration (from Johnson et al 1993). Field capacity is defined as the volume of water that remains in wetted soil after excess has drained. Neither are truly constants for a given soil, but they are commonly used as such in modeling.
Are there are any generic pedotransfer functions that can be used to estimate these parameters from sand/silt/clay fractions? These estimates will be used as priors in Bayesian data assimilation, and will thus be subsequently constrained by observations of soil moisture and transpiration.
- Johnson et al 1993 The Implementation and Validation of Improved Land-Surface Hydrology in an Atmospheric General Circulation Model. J. Climate (pdf)
- Miguez et al 2008 A semimechanistic model predicting the growth and production of the bioenergy crop Miscanthus giganteus: description, parameterization and validation. GCB-Bioenergy (pdf).
- Wikipedia "Field Capacity" and "Wilting Point".