A study was conducted to determine the effect of different land use on microbial biomass carbon, organic carbon and nitrogen stock on a tropical acric luvisols at Ibadan, Oyo State, Southwestern Nigeria. Soil samples were collected in 2014 using a quadrant approach across ten plots at the surface (0-15 cm) and sub-surface (16-30 cm) depths in four different land use systems of (i) 8-year old citrus, (ii) 8 year old cacao, (iii) 8 year oil palm and (iv) a fallow land of over 25 years. Significant differences in soil physical and chemical properties, microbial biomass carbon, carbon and nitrogen stock in different land use types at two depths (0-15 and 15-30 cm) were observed on soil properties important for sustainable crop production. Fallow land use, oil palm plantation and cocoa plantation were characterized by higher carbon and nitrogen stock, microbial biomass carbon, total nitrogen, organic carbon, available phosphorus, marginally low exchangeable bases except for Ca and Mg with relatively higher values and marginal C/N ratio. These land use also had lower bulk density, high total porosity, high moisture content and optimum soil temperature level. These results suggest that incorporation of optimum fallow cycle with appropriate land use in combination with soil enriching cover and tree crops in the study area will increase carbon and nitrogen stock while imitating a forest ecosystem condition which would help restore soil fertility in degraded lands while reducing greenhouse gas fluxes.
Status of soil organic carbon and nitrogen stocks in Koga Watershed Area, Northwest Ethiopia