Estimating soil hydraulic conductivity and macroscopic capillary length from the disk infiltrometer

The disk infiltrometer is increasingly used to measure in situ soil hydraul ic properties in the field. Several procedures have been proposed for deter mining soil hydraulic conductivity from disk infiltrometer data. However, t he procedures require steady-state infiltration rates at several tensions, which limits their applications in the field. In this study, two methods we re developed to estimate soil hydraulic conductivity and macroscopic capill ary length using soil water fluxes at any infiltration time under the disk infiltrometer. The proposed procedures do not require steady-state infiltra tion rates but infiltration data at any time. Therefore, the time required for field infiltrometer experiments can be dramatically reduced. Meanwhile the new procedures provide high estimation accuracy of soil hydraulic condu ctivity and macroscopic capillary length. Extensive numerically simulated d ata were used to examine the methods for various soils and different radii and tensions of the disk infiltrometer. The proposed methods are especially useful for estimating soil hydraulic conductivity and macroscopic capillar y length of fine-textured soils, using infiltration data collected during a short experiment period with a relatively large infiltrometer.