Long-Term Effects of Exotic Tree Species (Tectona grandis Linn. F.) on the Status of Extractable Micronutrients in the Southern Guinea Savanna of Nigeria

Abstract

In an effort to combat the declining forestry resources through the establishment of exotic tree species like Tectona grandis, this have lead to processes associated with soils underneath these trees that have not been properly elucidated, particularly
the distributions of extractable micronutrients. Results from the study showed that 0.1M HCl extractable Zn, Cu and Fe in the surface and subsurface horizons varied from 0.74 to 4.68, 0.04 to 2.64 and 0.55 to 44.25 mg kg^-1. The DTPA extractable Zn, Cu and Fe ranged from 0.40 to 1.99, 0 to 4.37 and 2.11 to 24.06 mg kg^-1 for both horizons. The extracting properties of these solutions indicated that 0.1M HCl, extracted more Zn, while DTPA extracted more Fe under the plantations. The extractable micronutrient contents showed an increase with aging plantation. The study therefore implied that Tectona grandis has an extractive property on micronutrient particularly on soils that are low in these nutrients.

Nigerian Journal of Soil and Environmental Research Vol. 7 2007: pp. 15-22