Comparison of tension infiltrometer, pressure infiltrometer, and soil core estimates of saturated hydraulic conductivity

Saturated hydraulic conductivity (Ks,) is an important soil property that is difficult to measure. Positive-head tension infiltrometer (TI) and single-ring pressure infiltrometer (PI) techniques show promise for measuring Ks,, but there have been few field tests or comparisons with-other methods. The TI, PI, and classical undisturbed soil core (SC) methods for measuring K-SAT were compared on single-grain sand, structured loam, and cracking-clay loam soils under conventional tillage (CT), no-tillage (NT), and native woodlot (WL) managements. Of the 27 between-method correlations (3 methods x 3 soils x 3 managements), only four were significant (P < 0.05). The TI method yielded lower Ks,, values under high-permeability conditions (K-SAT greater than or equal to 10(-4) ms(-1)) relative to the other methods, as evidenced by lower geometric mean K-SAT (K-GM), lower maximum K-SAT (K-MAX), and lower minimum K-SAT (K-MIN) values. The 0.10-m diam. by 0.10-m-long SC method cores may have been too small to yield representative estimates of K-SAT in the cracking-clay loam and in the NT and WL managements of the sand and loam, as indicated by high coefficients of variation (CVs), inconsistent K-GM values, or high K-MAX values relative to the other methods. Erratic K-MAX and K-MIN values, along with high CVs, suggest that the 0.10-m-diam. PI ring may have been too small to adequately sample the cracking clay loam soil under CT and NT management. Further work appears warranted for developing K-SAT measurement methods, interpreting K-SAT results, and determining appropriate K-SAT methods for various soil types and conditions.