Estimation of Soil Carbon and Spatial Variability of Soil Properties in Omo Biosphere Reserve, Ogun State, Nigeria

Abstract

Understanding the role of soil in climate change mitigation requires accurate estimates of soil carbon. Soil Organic Carbon (SOC) plays a vital role in mitigating global climate change, and alleviates land degradation and enhances crop production and food security.  Soil samples were collected with soil auger from 25 sample plots (30 m x 30 m) at depths of 0 – 15 cm in Omo Biosphere Reserve. The quantity of SOC per hectare was determined using a bulk density measurement.  To examine the spatial variance of soil parameters, descriptive statistics and Kriging spatial interpolation techniques were employed. The estimated quantity of soil organic carbon in the Omo biosphere spans from 9.89 to 76.61 ton/ha with a mean of 29.14 ton/ha, whereas the estimated amount of CO₂ sequestered ranges from 36.31 to 281.15 ton/ha with a mean of 106.94 ton/ha. The estimated total content of the SOC in the biosphere reserve was 11,801.43 tons, while the CO₂ equivalent is 43,311.25 tons.  Due to varying nuggets to sill ratios, the soil properties displayed varied spatial dependence. Strongly spatially dependent were OM, N, Cu, Na, and K, somewhat spatially dependent were Mn, Fe, Mg, Sand, and Clay and weakly spatial dependent were OC, pH, P, Zn, Ca, Silt and CEC. The study concluded that monitoring soil degradation through details soil mapping is an important step in reducing emission and enhancing soil carbon sequestration.