Variations in Soil Properties as Influenced by Land Use and Soil Depth in a Derived Savannah Ecology of Southwestern Nigeria.

Soil physical and chemical properties are strongly influenced by soil management systems and changes in land use. The study was carried out in Iseyin LGA of Oyo state which is a derived savannah zone under four different land use types’ arable, grazing, fallow and tree crops. A total of twenty four soil samples were collected at two depths i.e. 0-15cm and 15-30cm, from the study area using the cluster sampling technique, profile pits were also dug on each land use type so as to classify the soil. The samples were subjected to both physical and chemical analysis to determine the fertility status of the area. Soil textural fractions varied with land use with the sand particles having the highest percentage of 76.2 % and 71.5% under arable and tree crops land use. This was followed by silt and clay fractions with values of 27.2 % and 10.64 % respectively in the grazing areas. The soils of the areas are mostly sandy loam and it also varied with depth with the top soil having higher particles than the sub soil. With respect to the soil chemical properties, the organic carbon content of the soils was generally moderate, it varied from 0.91% to 1.68 % for 0-15 cm depth while at 15-30 cm it ranged between 0.40 % - 1.24 %. The pH varied significantly with land use while the total nitrogen did not show any significant difference with all the land use types and soil depth, it ranged between 0.03 % - 0.08%. Available phosphorus and potassium contents were also not significant across all the land use types and soil depth