Assessment of Chemical Properties of Soils Derived from Basement Complex Rocks of the Jos Plateau

Abstract

Information on the chemical characteristics of soils is required in the sustainable the management of soil fertility and productivity. The objective of this study was to determine chemical characteristics of basement complex derived soils of the Jos Plateau. Soil study followed the approach in the Soil Survey manual and began by identification of three geologic units: granite gneiss, biotite granite and migmatite. Furthermore, eighteen soil profile pits were dug in each geologic units and eighty-four samples were taken from genetic horizons. Standard laboratory procedures were used to analyze soil samples for pH, organic matter, nitrogen and phosphorus.  Results showed that organic matter contents in the soils were generally low and seemed to influence the distribution of nitrogen in the soils. Consequently, contents of total nitrogen were low. Mean contents of pH in the A horizon were 5.15, 4.64 and 5.58 respectively for soils derived from granite gneiss, biotite granite and migmatite. Low pH levels are linked to the basic cations draining out of the profile and the acidic character of the basement complex rocks from which the soils were formed. Soil reaction in most cases indicated that soils had a net negative charge. Available P contents in the magmatic soils was significantly higher than those of other geologic units. Effects of granite gneiss, biotite granite and migmatite parent materials on variation in soil chemical properties were more noticeable for soil reaction and available P contents.