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Land use management effects on soil hydrophobicity and hydraulic properties in Ekiti State, forest vegetative zone of Nigeria

Olorunfemi, Idowu Ezekiel, Fasinmirin, Johnson Toyin
Catena 2017 v.155 pp. 170-182
bulk density, carbon, cation exchange capacity, correlation, cropland, ethanol, forests, growers, hydrophobicity, infiltrometers, land use planning, managers, organic matter, porosity, scientists, soil density, soil sampling, soil types, soil water, unsaturated hydraulic conductivity, water content, water holding capacity, water management, Nigeria
This study was conducted to characterize soil hydrophobicity, unsaturated hydraulic conductivity and sorptivity under different land uses (i.e croplands, plantation agriculture and natural forests) and soil types in southwestern Nigeria. In this study, a total of 105 different points in 35 different locations comprising of the 3 land uses were sampled in the study areas. Random sampling pattern of 3 sampling points per sample location were carried out and undisturbed soil samples were collected at depths up to 15cm from the different locations. Handheld mini disk infiltrometer at a steady-state flow of −2cm water suction rate was used to determine the unsaturated hydraulic conductivity, water and ethanol sorptivity at each land use site. In addition, the effects of antecedent soil moisture contents (MC), soil bulk density (BD), total porosity (PT), soil water holding capacity (WHC), organic matter content (SOM), and cation exchange capacity (CEC) on soil hydrophobicity, unsaturated hydraulic conductivity and sorptivity were determined. The mean hydrophobicity index, R, showed a decreasing trend in the order: natural forest˃plantation agriculture˃croplands, whereas, mean hydraulic conductivity values showed an increasing trend in the order: natural forest<plantation agriculture<croplands. Hydraulic conductivity resulted to a negative correlation with hydrophobicity among all sampled soils. In all the sampled soils, index of soil hydrophobicity (R) correlated significantly (p≤0.01) with organic matter content, organic carbon and cation exchange capacity (CEC). Soil sorptivity to water correlated negatively with moisture content among all samples at p≤0.05. Soil ethanol sorptivity showed significantly positive correlation with organic carbon, organic matter content and cation exchange capacity among all the soil samples at a p≤0.05. Soil properties such as organic matter content, bulk density, and aggregate sizes influence the infiltration characteristics of soils of the study areas. Findings from this research has provided a better understanding of soil characteristics and water management under different land uses, which will be of utmost usefulness to land managers, growers, hydrologist and soil scientists.