Estimation of Topsoil Variability from Continuous 2-D Subsurface Images of in-situ Resistivity and Selected Soil Properties


  • A.B. Eluwole and M.O. Olorunfemi Department of Geophysics, Federal University Oye-Ekiti, Ekiti State Nigeria


In-situ, Selected topsoil properties, Horizons, 2-D subsurface soil variability, Continuous 2-D subsurface resistivity


The study was carried out to determine interplay between continuous 2-D subsurface variability of in-situ soil electrical resistivity and selected topsoil properties. In-situ resistivity measurements were taken using the Wenner electrode array with electrode spacing (a) of 8 cm and 128 cm to constrain measurements to the O (0 – 3 cm) and A (3 – 50 cm) horizons respectively. Soil samples were also taken from the O and A horizons and were analyzed for particle size distribution, moisture content and pH. The resistivity values ranged between 241 ohm-m and 1786 ohm-m, while the moisture content and pH ranged from 4.11% to 12.6% and 5.1 – 6.8 respectively. Texturally, the sandy loam and loamy sand textures were observed. On the 2-D subsurface soil properties variability maps, low, moderate and high values were observed. Soil properties with low to moderate values were classified as sandy clay/clayey sand with respect to resistivity; permanent wilting point with respect to moisture content and moderately acidic – slightly acidic with respect to pH. The soil properties with high values were classified as sand, plant available water and neutral in terms of resistivity, moisture content and pH. Predominantly, the sandy loam texture was characterized by low to moderate resistivities while the loamy sand texture corresponded to high resistivities. Resistivity reduced with increasing moisture content (plant available water) while pH approached neutrality. In the same vein, high resistivity corresponded to low moisture content (permanent wilting point) with pH approaching acidity. The continuous 2-D subsurface resistivity variation was attributed to soil variability.


Author Biography

A.B. Eluwole and M.O. Olorunfemi, Department of Geophysics, Federal University Oye-Ekiti, Ekiti State Nigeria