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

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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:

θ = θ_R + a_1 \exp(-x/p_1) + a_2 \exp(-x/p_2)

where θ is the gravimetric water content.

Usage

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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.

Author(s)

Anderson Rodrigo da Silva <anderson.agro@hotmail.com>

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

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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)

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