Effect of land use and slope on selected soil properties of an Alfisol in Afaka forest Area, Northern Guinea Savanna of Nigeria

Land use changes from forest into cultivated ecosystems result in negative impact on soil structure and quality. The purpose of this study was to determine effect of land use and slope on selected properties and quality of an Alfisol in Afaka forest, Northern Guinea savanna of Nigeria. Land use systems, including natural forest and cultivated land were identified. Eighteen (18) composite disturbed and undisturbed samples were collected from depth of 0-5 and 5-10cm for analysis of pertinent soil properties in the laboratory using rigid grid procedure. Most physical and chemical properties show relative variations in response to land use types and geomorphic positions. Textural classes of soils under all the land uses on different topographic positions were sandy loam. Results indicate that the soils had high degree of weathering potentials, low to moderate bulk density at 0-5cm depth values range between 1.42 to 1.49 Mg m-3 in forest and cultivated land, bulk density at 5-10cm depths had values ranging between 1.34 and 1.46 1.Mg m-3 for forest and cultivated land respectively. The pH (H2O) ranged from 6.9 to 7.16 in the land uses. The electrical conductivity in the land uses was 0.13 dS/m and 0.12 dS/m was obtained for forest and cultivation land respectively, with highest EC at upper slope 0.16 dS/m. The total nitrogen content of 1.21 g kg-1 and 1.11 g kg-1 for forest and cultivation land uses was recorded. The highest available phosphorus of 8.78 mg kg-1 and 5.47 mg kg-1 was recorded under cultivated and forest land use while lowest value 4.12 mg kg-1 of available phosphorus was recorded at middle slope. Results indicate that soil fertility parameters were moderate to low in soils of cultivated land and all slope positions, suggesting that soil fertility management is required in order to make agriculture sustainable on Afaka area.