PROPERTIES OF SOILS ALONG A TOPOSEQUENCE UNDERLAIN BY COARSE GRAINED GRANITE GNEISS IN IFE AREA SOUTH WEST NIGERIA

Abstract

Research has shown that soil profiles are influenced by five separate, yet interacting factors: parent material, climate, topography, organisms and time which give soil profiles their distinctive character. Topography however, plays a major role in the variation of soil properties and nutrient distribution along a non-uniform agricultural landscape. This study was conducted to investigate the effects of topography on chemical properties of soil underlain by coarse grained granite gneiss at the teaching and research farm of Obafemi Awolowo University Ile Ife. Three profile pits was established at different physiographic positions along a toposequence (upper, middle and lower positions) were considered for this study. A total of eleven (11) samples were collected for routine laboratory analysis from the established horizons. The results revealed that the clay content increased with increase in profile depth while sand content decreases. Organic matter content was relatively low 0.2 – 1.35%, a result of continuous cultivation in the area. The values of available P (1.29 – 5.40ppm) showed that it is inadequate for crop production. The pH, exchangeable cations and exchangeable acidity values fluctuate across the pedons under investigation. The correlation between slope position and chemical properties showed that no singular property consistently showed the same level of significance on the entire slope.
 For effective management of the soils, organic inputs and usage of vegetal cover such as planting of cowpea and other crawling plants of economic importance should be adopted to assist in improving the organic matter content, conservation management practices should also be employed to prevent rapid soil degradation across the topography.