Evaluation of Physical Characteristics of Soils Derived from Basement Complex Rocks of the Jos Plateau

The physical characteristics of soils to a large extent influences soil productivity.  The objective of this study therefore is to evaluate the physical characteristics of soils derived from basement complex rocks of the Jos Plateau. According to the methodology outlined in the Soil Survey manual, the stratification of the study region into three geologic units—granite gneiss, biotite granite, and migmatite—was the first step in the soil research process. Additionally, soil samples were collected from genetic strata and soil profile pits were dug in each of these geologic units. Following standard procedure soils were analyzed for color, particles size distribution, structure, and bulk density. Results indicated that physical soil characteristics over the geologic units studied were in most cases similar. However significant differences were observed in particle size distribution in the A-horizons. Clay content in the A horizon of these soils generally ranged from a minimum of 8% to a maximum of 28%. Clay content in the A-horizons of the magmatic soils were significantly higher (P<0.05) than soils over granite gneiss but statistically similar (P>0.05) to those of biotite granite. Particle size distribution data indicate that the soils have undergone intensive weathering. Soil structures were on the average moderately developed in the soils studied with angular and sub-angular blocky structures. Although there was evidence of soil compaction to suggest plant root development could be affected or inhibited in these soils. .