hemc: High-Energy-Moisture-Characteristics Aggregate Stability In soilphysics: Soil Physical Analysis

Description

A function to determine the modal suction, volume of drainable pores, structural index and stability ratio using the high-energy-moisture-characteristics (HEMC) method by Pierson & Mulla (1989), which is used to analyze the aggregate stability. Before using `hemc()`, the user may estimate the parameters of the Modified van Genuchten's Model through the function `fitsoilwater5()`.

Usage

 ```1 2 3 4``` ```hemc(x, theta_R, theta_S, alpha, n, b1, b2, graph = TRUE, from = 1, to = 30, xlab = expression(Psi ~ (J~kg^{-1})), ylab = expression(d ~ theta/d ~ Psi), ...) ```

Arguments

 `x` a vector containing matric potential values. `theta_R` a numeric vector of length two containing the parameter values in the following orde: fast and slow. `theta_S` a numeric vector of length two containing the parameter values in the following orde: fast and slow. `alpha` a numeric vector of length two containing the parameter values in the following orde: fast and slow. `n` a numeric vector of length two containing the parameter values in the following orde: fast and slow. `b1` a numeric vector of length two containing the parameter values in the following orde: fast and slow. `b2` a numeric vector of length two containing the parameter values in the following orde: fast and slow. `graph` logical; if TRUE (default), a graphical solution is shown). `from` the lower limit for the x-axis `to` the lower limit for the x-axis `xlab` a label for the x-axis `ylab` a label for the y-axis `...` further graphical arguments

Value

A list of a two objects: 1) a matrix containing the Modal Suction, the Volume od Drainable Pores (VDP) and the Structural Index for both, fast and slow wetting; and 2) the value of Stability Ratio.

Author(s)

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

References

Pierson, F.B.; Mulla, D.J. (1989). An Improved Method for Measuring Aggregate Stability of a Weakly Aggregated Loessial Soil. Soil Sci. Soc. Am. J., 53:1825–1831.

`fitsoilwater5`
 ```1 2 3 4 5``` ```hemc(x = seq(1, 30), theta_R = c(0.27, 0.4), theta_S = c(0.65, 0.47), alpha = c(0.1393, 0.0954), n = c(6.37, 7.47), b1 = c(-0.008421, -0.011970), b2 = c(0.0001322, 0.0001552)) # End (Not run) ```