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This study evaluated the effect of mound building termites on the increase in the quantity of fine particles of the dimension of clay on the surface of coastal plain sands of south-eastern Nigeria. Six termite mounds were selected in different locations, destroyed completely and sampled in three replications. Surface and subsurface soils were sampled within the periphery of the termite mounds in similar replications as the mounds. Samples were processed and analyzed in the laboratory. Data were analysed using ANOVA, correlation and principal component. Termite mounds were not common but massive, with base diameter more extensive than height. The major determinants (responsible for 28%) of the effects of termite activities on the surface characteristics are total sand, clay and silt + clay. Termite mounds were similar to the surface soil in available phosphorus, exchangeable sodium and potassium, effective cation exchange capacity, fine sand and silt. These similarities result from homogenization through erosion and redistribution of the mound material within the surface soil vicinity. The fortified mound materials redistributed in surface soil vicinity is responsible for the high clay, elevated pH, enhanced effective cation exchange capacity, improved structural stability, minimized leaching and subsequently improved fertility of coastal plain sands.

Knowledge of soil physical and chemical properties is a key to making agronomic and environmental decisions. The objective of this study was to assess the extent of spatial dependence and spatial structure of some soil physical properties and implications on pedogenesis and management in the basement complex soils of southwestern Nigeria. Surface soil (0-15cm) samples were collected at 10 m 2 rigid grid intervals in a 0.5 hectare plot under fallow along Parry road in University of Ibadan. Classical statistics and geostatistics were adopted in analysis of data. Among the nine measured soil physical properties, sand, coarse sand and bulk density were least variable with coefficient of variation (CV) <15%. Moderately variable (CV >15<35%) properties included clay, silt, silt + clay and silt/clay ratio (SCR), whereas fine sand and saturated hydraulic conductivity were highly variable (CV >35%). The nugget to sill ratio showed that clay (12.5%), silt (9.9%), fine sand (17.0%), silt + clay (5.4%), SCR (25.7%), bulk density (18.1%) and hydraulic conductivity (12.2%) were strongly spatially dependent, while total sand (40.4%) and coarse sand (29.2%) contents were moderately spatially dependent indicating intrinsic variation attributable to soil particle size and mineralogy. Pearson correlation coefficients of the semivariances of the soil physical properties indicated that there were very few significant (p<0.05) relationships (i.e. 16% of the soil physical property pairs). It was observed that those semivariances that displayed significant correlation with each other had similarity in the appearance of their contour maps. The implication is that significantly correlated variables could be representative for site specific agronomic and environmental management and for study of pedogenesis.

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Geostatistical analysis facilitates site-specific farming, soil and sanitary landfill management, sustainability and health. The objectives of this study were to assess the extent of variability, spatial dependence and structure of soil particle sizes, pedological and management implications in the coastal plain sands soils of southeastern Nigeria. Surface (0-15cm) and subsurface (15-30cm) soil samples were collected at 10m 2 intervals (rigid grid nodes) in a 100m by 100m plot at the one year fallowed portion of Teaching and