Comparison of the physical and chemical properties of soils under natural forest and Gmelina plantation.

Abstract

Changes in physical and chemical characteristics of soils as affected by age of Gmelina and position on the slope were studied and compared with those of an adjacent natural forest. There were no significant differences in the effects of Gmelina and natural forest on the physical properties of the soi1, though soils under Gmelina had higher bulk densities. The chemical analysis showed that the upper and the lower slopes of the plantations had a higher organic carbon contents, 2.38% and 2.24% and total nitrogen contents, 0.21% and 0.20% than the middle slope with 1.91% and 0.17% organic carbon and total nitrogen respectively. Soils under Gmelina plantations, especially 1982 plantation compared favorably with those of natural forest in N, 0.22%, P, 82.13 mg/kg, organic carbon, 2.59% and mg, 2.42 Cmol kg-1, when compared with 0.23%N, 78.63mg/kgP, 2.5% Organic Carbon and 2.52 CmolK-lMg values of the natural forest. Phosphorus and contents of soils under Gmelina increased with age while the oldest Gmelina plantation has the highest K content.

Keywords: Gmelina, Toposequence, Bulk density, Nutrients.