Spatial Analysis of Particle Size Distribution of Soils Formed on Basement Complex Materials in the Southwestern Nigeria

Variability in soil properties is a critical element for agronomic and environmental decision making processes. This study therefore assessed the extent of spatial dependence and spatial structure of particlesize distribution in 0.49 hectares of land and their implications on pedogenesis and management of basement complex soils of southwestern Nigeria. A total of forty-nine (49) surface soil (0 – 15 cm) samples were collected at 10 m2 rigid grid (node) intervals in a plot under fallow at University of Ibadan Teaching and Research Farm, Ibadan. Classical statistics (including statistics of dispersion, test of normality andcorrelation analysis) and geostatistics were adopted in evaluation of spatial variability of soil particle size distribution. The results of coefficient of variation indicated that sand, and coarse sand contents were leastvariable (1535%). Spatial dependence of the soil separates indicated that clayand coarse sand had 16.6% and 24.6%, respectively and were strongly spatially dependent. Moderately spatially dependent soil properties included silt (46.5%), fine sand (59.7%), silt + clay (54.4%) and SCR(52.9%), while total sand (93.6%) was weak. The Pearson correlation coefficients of the semivariances indicated significant relationships between sand and silt + clay (r = -0.99, p