Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 21, 2001
Publication Date: October 21, 2001
Technical Abstract: Estimates of hydraulic conductivity obtained using a tension disc infiltrometer can be affected by soil layering near the surface. Two-dimensional infiltration from a disc source was simulated to evaluate the influence of a layered soil on estimates of hydraulic conductivity obtained using Wooding's equation for the analysis of steady-state flow. Estimated hydraulic properties from field experiments were used as inputs to simulate infiltration into a soil with a slowly-permeable layer at 5, 10, and 15 cm from the surface. The depth to the second layer, initial water contents, and measurement duration at each supply pressure head influenced the error with which conductivities were estimated. Long duration infiltration experiments at high flow rates and high initial water contents produced the largest errors in the estimated conductivity when the second layer was 5 cm below the surface. For soils with a slowly-permeable elayer near the surface, it is recommended that infiltration times and maximum water contents be established to minimize the influence of this layer on estimated hydraulic conductivities of the surface layer.