soilphysics (version 5.0)

soilwater3: Soil Water Retention, based on the Dexter's (2008) formula

Description

Function to calculate the soil water content based on the Dexter's (2008) formula. It is based on the segregation of pore space in two categories what are called bi-modal pore size distributions. In this model, the pore space is divided into two parts: the textural porosity which occurs between the primary mineral particles, and the structural porosity which occurs between micro aggregates and/or any other compound particles. This is called the double-exponential (DE) water retention equation, given by: $$\theta = \theta_R + a_1 \exp(-x/p_1) + a_2 \exp(-x/p_2) $$

where \(\theta\) is the gravimetric water content.

Usage

soilwater3(x, theta_R, a1, p1, a2, p2)

Arguments

x

a numeric vector containing the values of applied air pressure.

theta_R

a parameter that represents the residual water content.

a1

a parameter that represents the drainable part of the textural pore space in units of gravimetric water content at saturation.

p1

a parameter that represents the applied air pressures characteristic for displacement of water from the textural pore space.

a2

a parameter that represents the total structural pore space in units of gravimetric water content at saturation.

p2

a parameter that represents the applied air pressure that is characteristic for displacing water from the structural pores.

Value

The the soil water content.

References

Dexter et al. (2008). A user-friendly water retention function that takes account of the textural and structural pore spaces in soil. Geoderma, 143:243-253.

See Also

fitsoilwater3, soilwater, soilwater2

Examples

# NOT RUN {
soilwater3(x = 0, theta_R = 0.058, a1 = 0.233, p1 = 3.274, a2 = 0.070, p2 = 1.78)
soilwater3(x = 3, theta_R = 0.058, a1 = 0.233, p1 = 3.274, a2 = 0.070, p2 = 1.78)
soilwater3(x = 4, theta_R = 0.058, a1 = 0.233, p1 = 3.274, a2 = 0.070, p2 = 1.78)

# End (not run)
# }