Spatial dependence of some physical properties of a typic plithaqaualf on the basement complex in southwestern Nigeria

Abstract

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.

Cropping System Effects on Soil Quality for Three Agro-Ecosystems in India

“…Knowledge of soil properties is the key in making agronomic and environmental decisions (Obi et al ., 2010). Variability in soil properties has been observed due to various anthropogenic management practices and the soil-forming factor.…”

Pedogenesis of two lithologically similar soils under vegetation of contrasting features in Ohaji, south-eastern Nigeria

“…High variation in the clay fractions of the soils could be due to the existence of argillic horizons in the pedons; indicating wide variation in the clay contents of the horizons and increased clay down the soil profile. Soil properties manifest both long and short range variability and are multivariate in nature (Obi et al, 2010). This variability can be studied using CV in which case, ranking of CV of soil properties are grouped into different classes including least (< 15%), moderately (15 < 35%) and highly (> 35%) variable according to Wilding (1985).…”

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

“…The nugget semivariance expressed as a percentage of the total semivariance enables comparison of the relative size of the nugget effect among soil properties (Trangmar et al 1985). Several studies (Iqbal et al 2005;Duffera et al 2007;Santra et al 2008;Souza et al 2009, Obi and Nnadi, 2010, Obi et al, 2010a have shown that components of soil texture are strongly spatially dependent. Thus, influencing other soil properties (physical, chemical or biological) that may equally display strong spatial dependence.…”