Hydraulic Properties of a Clay Loam Soil and the Field Measurement of Water Uptake by Roots: III. Comparison of Field and Laboratory Data on Retention and of Measured and Calculated Conductivities

Abstract

Abstract Soil water characteristics obtained on soil cores in the laboratory at air pressures < 1 bar agreed substantially with pressure‐water content relations determined in the field. Thus, in field studies of soil hydraulics, measurement of either water content or pressure potential may suffice. When the laboratory data were supplemented with a doubletube measurement of the saturated conductivity, the relation between water content and conductivity was calculated using two methods. Of these, the one due to Millington and Quirk gave less accurate agreement with actual field measurements than did the method proposed by Laliberte, Corey and Brooks. The latter method, when based on double‐tube measurements in the field and pressure cells or similar measurements on cores in the laboratory, appears useful. Retention values measured with the pressure membrane method on disturbed soil samples were out of line with both field and core results, even when the disturbing treatments were minimized.