Abstract

Anthropogenic activities can destroy or drastically reduce the organic carbon contents of soils. This study was conducted to evaluate the effects of two land use management practices (arable land and oil palm land), soil depth and topography on soil organic carbon contents. The study was carried out in Ikole-Ekiti, Ekiti State, Nigeria. At each location, three topographic units were identified as upper slope, middle slope and lower slope at 50 m apart. A mini pit of 150 cm by 100 cm by 60 cm in length, breadth and depth, was dug and marked into delineated horizons of 0-20, 20-40 and 40-60 cm depths. The physical and chemical properties of all samples were determined. The data collected were subjected to analysis of variance (ANOVA) using the Randomized Complete Block Design (RCBD). In both agricultural land use types studied, the SOC was not significantly affected by (<0.05) slope levels and soil depths but the lower position recorded higher SOC contents at the surface soil depth (0-20cm). The highest mean SOC contents in the middle slope of both land use types can be due to tillage practices. Conservation tillage practices, crop residue management and addition of manure and compost should be recommended in order to increase and maintain soil organic content in the soils .

Keywords:Soil organic carbon(SOC), soil depth, topography, land use.