Hydraulic Conductivity and Penetration Resistance of a Tropical Rainforest Alfisol under Different Land Uses in Akure, Southwestern Nigeria

Abstract

Effects of different land use (Arable land; Teak forest/plantation; Natural forest; Banana plantation; and Construction site) on hydraulic conductivity, penetration resistance and hydrological changes of soils was investigated in Akure, southwestern Nigeria. The field experiment was conducted during the rainy season of 2013 in five (5) different locations based on land use pattern. Six points (approximately 60 m apart) were randomly selected from each location for the collection of soil samples following a grid sampling pattern. Soil infiltration rates, penetration resistance, soil moisture content, bulk density and porosity of the sites were measured. Cone penetration resistance was determined at depths 7.5, 15, 22.5 and 30 cm, while the soil moisture content and bulk density were determined at depths of 5, 10, 15 and 20 cm. Construction site demonstrated higher bulk density, higher penetration resistance and lower unsaturated hydraulic conductivity when compared with soils of other locations. Highest bulk density (1.88±0.06 g/cm3) was obtained at the soil surface layer of the construction corresponding to the highest penetration resistance value of 3.47 MPa. Strong and positive correlation was recorded between soil penetration resistance and bulk density within different land uses. The highest hydraulic conductivity was recorded under Natural forest with a mean value of 5.74 × 10-4 cms-1 and lowest (1.42 × 10-4 cms-1) in the Construction site. Results of the experiment provided the basis for proper selection, planning and implementation of land use schemes in the study area.