EVALUATION OF MICROBIAL CHARACTERISTICS OF SOIL INFLUENCED BY DECOMPOSED LEAF LITTER IN IBIAE OIL PALM PLANTATION, CROSS RIVER STATE, NIGERIA

This study evaluated the microbial characteristics of soil influenced by decomposed oil palm leaf litter in Ibiae Oil Palm Plantation, Cross River State, Nigeria. The study examined soil physical and chemical properties, microbial population, microbial biomass carbon and nitrogen, and enzyme activities across lower, middle and upper slope positions at 0-15 cm and 15-30 cm depths, using an adjacent non-oil-palm plot as control. Thirty-six soil samples were collected and analysed using standard laboratory procedures, while descriptive statistics and analysis of variance supported interpretation. Results showed that plantation soils were sandy loam, slightly acidic (pH 5.5-6.2) and richer in organic carbon, available phosphorus, exchangeable bases, microbial biomass and enzyme activity than the control. The lower slope and surface depth generally recorded the strongest biological performance, with higher bacterial counts, microbial biomass carbon (196.8 mg/kg), microbial biomass nitrogen (29.2 mg/kg), dehydrogenase, urease, amylase and lipase activities. The findings demonstrate that decomposed oil palm leaf litter improves soil biological quality and nutrient cycling, supporting its use as a sustainable residue-management strategy in tropical oil palm systems.