Investigation of soil moisture content over a cultivated farmland in Abeokuta Nigeria using electrical resistivity methods and soil analysis

摘要

A combined 1D and 2D electrical resistivity surveys as well as laboratory determination of soil moisture contents of topsoil in a University cultivated farmland is presented. Apparent resistivity data were measured along six traverses using Schlumberger and Wenner arrays while soil samples were collected from all traverses at depths of 0.5, 1.0, 1.5 and 2.0?m respectively. The ranges of resistivity and thickness of the topsoil, clayey sand and weathered layers are 78.0–1094.0?Ωm, 0.5–1.9?m; 110.0–275.0?Ωm, 1.1–11.9?m; and 19.0–274.0?Ωm, 1.1–14.0?m respectively. 2D resistivity inverted sections revealed three zones of resistivity anomalies: topsoil with resistivity 78.0–600.0??m for traverses within the farmland and that of two traverses along the entrances to the farm. The second resistivity zone represents a clay region of high moisture content with resistivity values less than 25.0?Ωm. The third layer represents weathered/fractured layer with relatively high resistivity values ranging from 116 to 600?Ωm. The 1D resistivity models showed effective depths of more than 30.0?cm while the 2D image lines revealed that active water uptake zone extends to about 3.0?m depth. All the collected soil samples belong to sandy loam while the soil moisture content values ranged from 45 to 74% at different soil depths of 0.5–2.0?m. The study has shown that the integrated methods provide important methods for better management of soil water reserves for improved agricultural production.