Saturated Hydraulic Conductivity in a Tropical Alfisol in South-West Nigeria

摘要

This study presents the results of a comprehensive laboratory investigation program on the spatial variability of saturated hydraulic conductivity within a 44.3 ha twin-forested watershed at the International Institute for Tropical Agriculture (IITA) Ibadan in south-west Nigeria. The saturated conductivity was excessively rapid. In pre-clearing 2001, the mean saturated hydraulic conductivity ranged from 178 cm h 1 for 15-20 cm depth to 336 cm h 1 for 0-5 cm depth.The standard deviation was often equal to or even more than the average. In addition to high values, the variability in saturated conductivity was also very high amongst the 14 sub-watersheds. The high variability in hydraulic conductivity was due to the effects of pre-clearing vegetation, influence of roots and stumps, activity of soil fauna (earthworm and termites) and the size distribution and percent of gravel and coarse fraction present. Empirical relationships have been developed between the hydraulic parameters and the properties of fines particles.