Suitability assessment of soils developed in coarse-grained granite and gneiss in humid rainforest area of Southwestern Nigeria, for maize and cassava production

Abstract

Suitability evaluation of soils developed in coarse-grained granite and gneiss in the humid rainforest area of southwestern Nigeria was carried out for maize and cassava production, using the parametric method. A soil profile pit was established on each of the four physiographic units of two toposequences. Eight profile pits were established and described following the FAO guidelines for soil profile description and thereafter sampled. The physical and chemical properties of the soil samples were determined in the laboratory, using standard methods. The land qualities of the soils were matched with the crop requirements for maize and cassava to obtain the soil suitability classes. Results showed the soils were rated presently not suitable (N1), permanently not suitable (N2), moderately suitable (S2), and marginally suitable (S3) for maize and cassava production. Major agronomic constraints were nutrient availability, nutrient retention and slope. In addition, soils of Jago series were limited by drainage, texture, high bulk density, shallow depth and low fertility. The soils were closely related but not homogenous. They varied in their potentiality with physiographic units for maize and cassava production. As a result, agronomic constraints in each physiographic unit calls for specific management practices to ensure sustainable use of the soil resources.