Comparison of Tension Infiltrometer, Pressure Infiltrometer, and Soil Core Estimates of Saturated Hydraulic Conductivity

Saturated hydraulic conductivity (KSAT) 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 KSAT, but there have been few field tests or comparisons with other methods. The TI, PI, and classical undisturbed soil core (SC) methods for measuring KSAT 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 × 3 soils × 3 managements), only four were significant (P < 0.05). The TI method yielded lower KSAT values under high‐permeability conditions (KSAT ≥ 10−4 ms−1) relative to the other methods, as evidenced by lower geometric mean KSAT (KGM), lower maximum KSAT (KMAX), and lower minimum KSAT (KMIN) values. The 0.10‐m diam. by 0.10‐m‐long SC method cores may have been too small to yield representative estimates of KSAT 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 KGM values, or high KMAX values relative to the other methods. Erratic KMAX and KMIN 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 KSAT measurement methods, interpreting KSAT results, and determining appropriate KSAT methods for various soil types and conditions.