Function to calculate the S index (Dexter, 2004) for evaluating the soil physical quality based on the Water Retention Curve (van Genuchten, 1980).
S = - n * (θ_S - θ_R) * (1 + 1/m)^{-(1 + m)}
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theta_R |
the residual water content. |
theta_S |
the water content at saturation. |
alpha |
a scale parameter of the van Genuchten's formula. |
n |
a shape parameter in van Genuchten's formula. |
m |
a shape parameter in van Genuchten's Formula. Default is 1-1/n (Mualem, 1976). |
vcov |
optional (default is |
nsim |
the number of Monte Carlo simulations; default is 999. It is used only if |
conf.level |
the confidence level; default is 0.95. It is used only if |
graph |
logical; if TRUE (defaul), the soil water retention curve is plotted. |
... |
further graphical arguments. |
A list of
h_i |
the modulus of the water potential at the inflection point. |
theta_i |
the water content at the inflection point. |
S.index |
the modulus of the S index. |
PhysicalQuality |
A character indicating the soil physical quality, as proposed by Dexter (2004). |
simCI |
the simulated confidence interval. It is stored only if |
conf.level |
the confidence level for the simulated confidence interval. It is stored only if |
Anderson Rodrigo da Silva <anderson.agro@hotmail.com>
Dexter, A. R. (2004). Soil physical quality Part I. Theory, effects of soil texture, density, and organic matter, and effects on root growth. Geoderma, 120:201-214.
Genuchten, M. T. van. (1980). A closed form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal, 44:892-898.
Mualem, Y. (1976). A new model for predicting the hydraulic conductivity of unsaturated porous media, Water Resource Research, 12:513-522.
soilwater
, fitsoilwater
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