Wd. Reynolds et Wd. Zebchuk, HYDRAULIC CONDUCTIVITY IN A CLAY SOIL - 2 MEASUREMENT TECHNIQUES AND SPATIAL CHARACTERIZATION, Soil Science Society of America journal, 60(6), 1996, pp. 1679-1685
Infiltration, drainage, and chemical leaching are strongly influenced
by the magnitude and spatial distribution of the field-saturated soil
hydraulic conductivity (K-fs). The Guelph permeameter (GP) method show
s promise as an effective means for held measurement of K-fs and its s
patial distribution, but its accuracy in medium- and fine-textured soi
ls is not well established. To further assess its accuracy and effecti
veness, the GP method was compared with the auger hole (AH) method at
the 0.5-m depth at 68 grid locations in a texturally uniform silty cla
y soil that had stable but spatially variable structure. The two metho
ds yielded similar geometric mean K-fs values (P < 0.001), as well as
similar semivariograms. The two methods were also positively correlate
d (r = +0.6565, P < 0.0001). We therefore concluded that the two metho
ds gave equivalent estimates of K-fs at this field site, and that the
GP method is capable of providing valid estimates of K-fs in at least
some fine-textured soils. The K-fs values were not correlated with soi
l texture, organic C content, or soil surface topography, but were neg
atively correlated (r = -0.7240 for GP method, r = -0.6070 for AH meth
od, P < 0.0001) with antecedent volumetric water content (theta(a)) me
asured in situ prior to the GP measurements using a down-hole time dom
ain reflectometry probe. The semivariogram for theta(a) was similar to
those for K-fs. These results suggest that the magnitude, range, and
pattern of variability of the K-fs measurements were controlled primar
ily by the well-developed and stable soil structure at the field site,
rather than by texture, organic C content, or surface topography.