Soil Quality Assessment of Different Land Use in Kabba Southern Guinea Savannah of Nigeria

The study assessed the soil qualities of five land use types; Oil palm plantation, Nursery site, Forest (Teak), Citrus orchard and Arable Crop land in Kabba College of Agriculture using selected biological indicators which include, Organic Carbon (OC), Total Nitrogen (TN), Microbial Biomass Carbon (MBC) and Microbial Biomass Nitrogen (MBN). An area of 40 m x 30 m that is representative of each land use was selected, sampled and analyzed following standard procedures for laboratory analysis. The highest values of OC (18.41 g/kg) and TN (7.95 g/kg) were obtained at the nursery site followed by Oil Palm (OC - 14.12 g/kg; TN - 6.56 g/kg), the lowest values were obtained at the Arable Crops site (OC - 10.53 g/kg; TN - 5.20 g/kg). The MBC values ranged from 307 – 498 mg/kg across the land use studied. The MBN values obtained in this study ranged between 16.93 - 34.41 mg/kg. The MBC/MBN ratios obtained in this study were relatively high and in the following order Forest land (26.5 mg/kg) > Oil Palm Plantation (21.3 mg/kg) > Citrus orchard (19.5 mg/kg) > Nursery site (15.9 mg/kg) > Arable Crops land (12.2 mg/kg) respectively indicating the predominance of fungi in these soils. It is recommended that sustainable practices that will encourage replenishment of C and N into the soil should be adopted in the study area.