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Field Application of a Portable Air Permeameter to Characterize Spatial Variability in Air and Water Permeability

^a Danish Institute of Agricultural Sciences, Dep. of Agroecology, Research Centre Foulum, P.O. Box 50, DK-8830 Tjele, Denmark
^b Environmental Engineering Section, Dep. of Life Sciences, Aalborg University, Sohngaardsholmsvej 57, DK-9000 Aalborg, Denmark

View larger version (35K): [in a new window]   Fig. 1. Portable permeameter used for measurements of ka,in situ (after Iversen et al., 2001b).

View larger version (19K): [in a new window]   Fig. 2. Soil water characteristic curves for the (a) Ap and (b) B horizons in the excavated profiles (n = 5). Error bars show ±1 SD. Also plotted is the water content of the soil at the time of measurement (shown by a circle and the drop lines).

View larger version (31K): [in a new window]   Fig. 3. Measurements of ka,in situ at all grid points in the Ap and B horizon at the five sites as a function of coarse sand content.

View larger version (11K): [in a new window]   Fig. 4. Experimental and fitted variograms of log-transformed measurements of ka,in situ at two depths at the Kølvrå and Simmelkær sites.

View larger version (20K): [in a new window]   Fig. 5. (a) Log-log relationship between Ks and ka,lab measured in the laboratory on the 6280-cm3 soil columns sampled in the grid and from the soil profiles. The 95% prediction interval and r2 are given (values of n, , and ß are found in Table 4). Also plotted is the log-log relationship found by Loll et al. (1999). (b) Log-log relationship between ka,lab and Ks from the present study in combination with the log-log relationship on 6280-cm3 soil columns found by Iversen et al. (2001a). Also plotted is the log-log relationship and 95% prediction interval found by Loll et al. (1999).

View larger version (16K): [in a new window]   Fig. 6. (a) Log-log relation between Ks measured in the laboratory and Ks estimated from ka using Eq. [8] (Loll et al., 1999). The data include measurement on the 6280-cm3 soil columns sampled in the Ap horizon in relation to the grid points and in the Ap and B horizon in relation to the excavated soil profiles. Root mean square error is calculated on the arithmetic means of each site from the log-transformed data (data from the excavated soil profiles only). (b) Log-log relation between Ks measured in the laboratory and Ks estimated from Rosetta (Schaap et al., 2001) and Eq. [9] (Poulsen et al., 1999a). The data include measurements on the 6280-cm3 soil columns sampled in the Ap and B horizons in relation to the excavated soil profiles. Values of Ks (measured) are arithmetic means of each site on the log-transformed data.