Different functions to estimate soil diffusivity from the air-filled pore space.
Usage
DSD0_millington_quirk(AFPS, TPS = NULL, tortuosity = NULL)
DSD0_moldrup(AFPS, AFPS_100, b_campbell)
DSD0_currie(AFPS, a_currie = 1.9, b_currie = 1.4)
DSD0_linear(AFPS, a_lin, b_lin)Details
DSD0_millington_quirk()is of the form \(D_s / D_0 = \Xi \cdot \epsilon\) where \(\Xi\) is the tortuosity factor (tortuosity) calulcated as \(\Xi = \frac{\epsilon^{(10/3)}}{\Phi^2}\) ; \(\epsilon\) is the air-filled pore space (AFPS) and \(\Phi\) is the porosity (TPS). From Millington & Quirk (1961).DSD0_moldrup()is of the form \(D_s / D_0 = (2 \cdot \epsilon_{100}^3 + 0.04 \cdot \epsilon_{100}) \cdot (\frac{\epsilon}{\epsilon_{100}})^{(2 + \frac{3}{b_{campbell}})}\) where \(\epsilon_{100}\) is the air-filled pore space at a matric potential head of -100 cm and \(b_{campbell}\) is the slope of the water retention curve. From Moldrup et al. (2000).DSD0_currie()is of the form \(D_s / D_0 = a \cdot \epsilon^b\) where \(a\) and \(b\) are fit parameter of an exponential model. From Currie (1960) with default values (a=1.9; b=1.4)from Troeh (1982).DSD0_linear()is a linear model of form \(D_s / D_0 = a \cdot \epsilon + b\).
References
Millington, R. J., & Quirk, J. P. (1961). Permeability of porous solids. In Transactions of the Faraday Society (Vol. 57, p. 1200). Royal Society of Chemistry (RSC). https://doi.org/10.1039/tf9615701200
Moldrup, P., Olesen, T., Schjønning, P., Yamaguchi, T., & Rolston, D. E. (2000). Predicting the Gas Diffusion Coefficient in Undisturbed Soil from Soil Water Characteristics. In Soil Science Society of America Journal (Vol. 64, Issue 1, pp. 94–100). Wiley. https://doi.org/10.2136/sssaj2000.64194x
Currie, J. A. (1960). Gaseous diffusion in porous media. Part 2. - Dry granular materials. In British Journal of Applied Physics (Vol. 11, Issue 8, pp. 318–324). IOP Publishing. https://doi.org/10.1088/0508-3443/11/8/303
Troeh, F. R., Jabro, J. D., & Kirkham, D. (1982). Gaseous diffusion equations for porous materials. In Geoderma (Vol. 27, Issue 3, pp. 239–253). Elsevier BV. https://doi.org/10.1016/0016-7061(82)90033-7