Abstract

This study examined the differences in the nutrient concentration of the parent material of teak plantations under basement and sedimentary rocks in south western Nigeria. Systematic line transect was employed to establish 18 plots (30 m x 30 m), each in Ilaro (sedimentary rock) and Olokemeji (basement complex rock) plantations which were 37, 40 and 42 years old while twelve rock samples each from 3 quadrants each of 30 m² were selected for rock nutrient analysis. Topsoil (0-15 cm) and subsoil (15-30 cm) samples, above-ground plant parts (leaf, bark, stem, twig and branch) and biomass parameters (bole height, girth, total height and crown diameter) were collected. The soil samples were analyzed for soil physicochemical and micronutrients while plant parts were analyzed for nutrient contents (nitrogen, phosphorous, potassium, calcium and magnesium) using standard procedures. Pearson’s correlation and regression analysis were used to establish the type and level of association between soil properties and vegetation parameters respectively at p<0.05. The result indicates that there is no significant difference between the various minerals found in the rocks of the two locations. Secondary test indicate that there is significant difference among the three horizons A, B and C on the mean concentration of phosphorus and iron with p = 0.008<0.05 and p = 0.046 < 0.05 respectively. The multiple comparisons  revealed that there is no statistical significant difference in phosphorous concentration between horizons A and B horizon but that there is a statistical significant difference between horizon A & C and B & C with p = 0.005< 0.05 for all.

Key words: Bedrock geology, parent rock materials, physical properties, physico-chemical properties, soil nutrients.