Characterization and Classification of a Landscape underlain by Basement Complex for Engineering Purposes

Abstract

Utility of soil survey reports could be increased if used for evaluation of soils for engineering and other purposes apart from agriculture. The physical characteristics of some soils on basement complex in southwestern Nigeria generated from semi detailed soil survey activities were used for Urban Land Use Capability (ULUC) Evaluation. Soil morphological/physical characteristics, vegetation, land use, physiography, surface forms, stoniness and micro-relief of the soils were studied. Six soil series (mapping units) were identified and characterized on a 470.1 hectare land. Soil physical parameters evaluated for the ULUC include hydraulic conductivity, penetrometer resistance, bulk density, gravel content and particle size distribution. The soil characteristics and qualities that are of engineering importance like drainage, texture, structure, bulk density, consistency, gravel content, water holding capacity are important in grouping the soil for ULUC evaluation. Soil series identified were Iwo and Ibadan (Ferric Luvisol / Arenic Kandiustalf), Iregun (Haplic Lixisol / Typic Hapludalf), Balogun (Ferric Lixisol / Vetradic Hapludalf), Egbeda (Rhodic Ferrasol / Kanhaplic Rhodustalf) and Matako (Luvic Arenosol / Typic Psammaquent). Approximately 90 per cent of the entire area was rated ULUC class B for multipurpose / urban uses imposing slight physical constraints for development. Soil survey and evaluation maps and report can also be veritable tools for engineering and other agricultural uses.

Key words: Soil characteristics, Soil Engineering properties, soil series, soil survey.