Land use effects on soil erodibility and hydraulic conductivity in Akure, Nigeria

This research was carried out to investigate the effects of three land use categories (grazed, cropped and forest land) on soil erodibility and hydraulic conductivity. Hydraulic conductivity was determined by a steady‐state flow using a mini‐disk infiltrometer while soil erodibility was determined following the Wischmeier and Smith equation. A suction rate of 2 cm s-1 was chosen for field infiltration measurement and subsequent estimation of soil hydraulic conductivity. The USDA textural classes for the land use types in forest, cropped and grazed lands are clay, sandy clay and sandy clay loam, respectively. The mean values of the hydraulic conductivity for the land uses/land cover are: forest land (0.00162±0.002019 cms-1), cropped land (0.002086±0.001299 cms-1), and grazed land (0.002244±0.002176 cms-1). Highest mean bulk density (1.45 ± 0.23 g cm‐3) and the lowest mean bulk densities (0.84 ± 0.14 g cm‐3) were observed in soils of forest and grazed land, respectively. Similarly, mean total porosity values ranged between 0.43 and 0.67 cm3 cm‐3. Highest organic matter was found out in the grazed soil (4.90%) as a result of the urine and excreta of the cattle. High organic matter was also observed in the forest soil (3.50%) but lower relative to grazed land. The soil erodibility was high in the sampled soils of grazed land with the value of 8.73 × 10-2 ±0.03, while the least erodibility (6.35 × 10-2 ± 0.02) was recorded in the forest land. These values indicate the eroding vulnerability of the three land uses. Key words: Infiltration rate, organic matter, bulk density, total porosity, land cover.