Soil characteristics in teak plantations and natural forests in Ashanti region, Ghana.
2000
Amponsah, I. | Meyer, W.
The aim of this study was to compare soils of natural forests converted to teak (Tectona grandis) plantations (21.3thinñ5.1 years) in the Offinso and Juaso Forest Districts in the Ashanti region, Ghana. Sites selected for this study were in the moist semi-deciduous forest zone and had nearly identical physiographic characteristics. In each of three natural forest stands and three teak plantations, 16 soil pits were examined and soil samples from the 0-20 (major rooting zone) and 20-40 cm depths were analysed for selected chemical and physical properties. In the 0-20 cm depths bulk density significantly increased (1.17 to 1.30 g/cm3), but soil organic matter (OM) content (13 to 11%), total nitrogen (0.3 to 0.2%), available phosphorus (4.2 to 1.2 mg/kg), and exchangeable K (0.4 to 0.3 cmol/kg), Ca (17.0 to 12.4 cmol/kg), and Mg (3.8 to 3.2 cmol/kg) significantly decreased in soils where natural forests were replaced with teak plantations. Similar results were found for the 20-40 cm soil depths. The higher nutrient content in soils under the natural forest may have been due to more litter contributions from understorey vegetation observed there. In the teak plantations nutrient leaching losses may have accelerated due to increased mineralization and the inability of teak to use the increase in available nutrient.
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