Self-starting Nls Power Models for Soil Water Retention
Function to self start the following nonlinear power models for soil water retention:
θ = \exp(a + b*Bd) ψ^c
(Silva et al., 1994)
θ = a ψ^c
(Ross et al., 1991)
where θ is the soil water content.
fitsoilwater() creates initial estimates (by log-linearization) of the parameters a, b and c and uses them
to provide its least-squares estimates through
a numeric vector containing values of soil water content.
a numeric vector containing values of water potential (Psi).
a numeric vector containing values of dry bulk density.
a character; the model to be used for calculating the soil water content. It must be one of the
A "nls" object containing the fitted model.
Anderson Rodrigo da Silva <firstname.lastname@example.org>
Ross et al. (1991). Equation for extending water-retention curves to dryness. Soil Science Society of America Journal, 55:923-927.
Silva et al. (1994). Characterization of the least limiting water range of soils. Soil Science Society of America Journal, 58:1775-1781.
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