Spatial Variability of Particle Sizes of Coastal Plain Sands Soils of Southeastern Nigeria

Abstract

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 10m2 intervals (rigid grid nodes) in a 100m by 100m plot at the one year fallowed portion of Teaching and Research / Commercial Farm of University of Uyo, in Use Offot, Uyo, Nigeria. A total of 100 samples were collected for each depth. Coefficient of variation (CV) of silt: clay ratio (SCR), silt, fine and coarse sand (surface) were highly variable at both soil depths, while coarse sand of subsurface soil was least variable (13.8%). Spatial dependence of the variables ranged from strong to moderate. The moderately spatially dependent variables included fine sand (36.7%), coarse sand (48.7%) on the surface, and SCR (33.7%) on the subsurface, while the remaining variables were strongly spatially dependent. Pearson correlation coefficients between the semivariances of the two depths showed significance in 52.8% of the entire relationships compared to 19.4% observed on the measured values of the particle sizes. Stronger spatially dependent variables correlated with more variables compared to the moderately spatially dependent variables. It was observed that most of the kriged maps produced displayed similarity in the sedimentation or depositional characteristics which now followed the depositional effect of the massive erosive forces. Kriging may combine correlation and spatial dependence to facilitate site specific farming, soil and sanitary landfills management, knowledge of pedogenesis and sustainability in the coastal plain sands soils.

Keywords: coastal plain sands, spatial structure, soil variability, particle sizes, pedogenesis