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Spatial Analysis of Particle Size Distribution of Soils Formed on Basement Complex Materials in the Southwestern Nigeria
Abstract
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 particle
size 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 and
correlation 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 least
variable (<15%), silt and silt + clay were moderately variable (>15<35%), whereas clay, fine sand contents and silt clay ratio were highly variable (>35%). Spatial dependence of the soil separates indicated that clay
and 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<0.01), and silt and silt clay ratio (r = 0.77, p<0.01). It was observed that clay, sand and silt + clay bear similar distribution in the field as shown by the prediction contour maps. These variables could receive similar treatment in precision farming, enhance knowledge of pedogenesis and sustainable environmental management.
size 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 and
correlation 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 least
variable (<15%), silt and silt + clay were moderately variable (>15<35%), whereas clay, fine sand contents and silt clay ratio were highly variable (>35%). Spatial dependence of the soil separates indicated that clay
and 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<0.01), and silt and silt clay ratio (r = 0.77, p<0.01). It was observed that clay, sand and silt + clay bear similar distribution in the field as shown by the prediction contour maps. These variables could receive similar treatment in precision farming, enhance knowledge of pedogenesis and sustainable environmental management.
