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Combining Laboratory and Field Measurements to Define the Hydraulic Properties of Soil
Author(s) -
Clothier B. E.,
Smettem K. R. J.
Publication year - 1990
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1990.03615995005400020001x
Subject(s) - macropore , hydraulic conductivity , soil water , sorptivity , infiltration (hvac) , soil science , outflow , thermal diffusivity , loam , geology , hydrology (agriculture) , environmental science , materials science , geotechnical engineering , chemistry , porosity , mesoporous material , composite material , biochemistry , oceanography , physics , quantum mechanics , catalysis
In situ field measurements and laboratory determinations are presented of the saturated and unsaturated flow properties of two contrasting soils. Field measurements were obtained with ponded rings or disc permeameters of different radii. A pressure‐transient outflow technique was used in the laboratory on undisturbed cores. The soil water diffusivity function from this, when integrated, provides a good rendition of the growth of the field‐measured sorptivity as the surface potential, ψ o , approaches zero. The undisturbed wetting hydraulic conductivity K (ψ) from the cores of both soils merged neatly with the near‐saturated field results. One soil from within the herbicide strip of an apple orchard had a smoothly continuous K (ψ) befitting its texture. However, the K (ψ) of the other soil, from a dairy pasture, displayed a matrix‐macropore dichotomy due to its high level of soil floral and faunal activity. Here, a mean pore size weighted for unsaturated flow, when ψ o < −100 mm, was 17 ± 4 µm. For ponded infiltration, this changed abruptly to 2.2 ± 0.6 mm. Large and connected macropores caused K to change three orders of magnitude as ψ o went from just −100 mm to zero.