Geotechnical Properties of Soils as Influenced by Land Use in a Humid Environment

Abstract

We investigated some geotechnical properties of soils of Port Harcourt in 2009 under three land use types, namely mechanically cleared land, on-going building constructions and fallow land. A combination of target and random soil survey techniques guided field studies. Five soil samples were collected in each land use, giving a total of 15 soil samples which were air-dried and sieved. These soil samples were subjected to routine laboratory analysis and resulting data were analyzed statistically using means and correlation analysis. Soils were sandy, of slight to neutral acidity (pH = 5.9-7.6). Disturbed soils were older (silt-clay ratio= 0.13- water 0.50) when compared with fallow having a mean value of 2.1. Plasticity index values were low (< 35%) and differed due to the land use: 11.63% (building site), 12.29% (mechanically cleared land) and 14.57% (fallow). There was low colloidal activity: 0.36 (building site), 0.40 (fallow) and 0.41 (mechanically cleared land). Highest recorded maximum dry density was found in building site (2.03 Mg mG3), while 24.87% optimum moisture content was obtained in fallow soils. Plasticity index showed good relationships with moisture, clay and colloidal activity in the study sites.

Keywords

• Atterberg limits
• Clay activity
• Land use
• Tropics