Comparison of Methods for Determining Hydraulic Conductivity

The hydraulic conductivity function K(θ) for different profile layers of a lateritic sandy loam soil was evaluated by computational procedure (modified Marshall) based on pore-size distribution, and hot air drying technique (modified Bruce and Klute's method) and the results were compared with that estimated by instantaneous profile method (IPM). The K(θ) determined by computational and hot air drying techniques were steeper in upper layers (0 to 15, 15 to 25 and 25 to 55 cm) and less so in lower depths (55 to 85 and 85 to 115 cm) than that measured by instantaneous profile method. K measured by IPM was larger in magnitude than that estimated by hot air drying (HAD). Still lower were the values derived from computational procedure. The differences between K values of computational and IPM as well as of computational and HAD methods were, in general, higher in deeper layers and also in drier range of soil water. In wet range, there was a tendency of convergence of K(θ) functions especially those derived from hot air drying and field methods.