Organic carbon dynamics along a toposequence in a peri-urban site

The pattern of carbon (C) storage in soils has implications for agriculture and the environment. Dynamics of organic C, in the 0- to 20-cm soil depth along a toposequence in a peri urban site in Sierra Leone, West Africa, were studied. Organic C was determined by the dry-combustion method on the following aggregate size fractions: whole soil (< 2000 mu m), 250 - 2000 mu m, 53 - 250 mm, and 53 mu m. Mean organic C content of whole soil ranged from 4.8% on the backslope to 9.3% on the toeslope. Organic C content of aggregate size fractions increased with decreasing aggregate size. The amount of soil and organic C present in aggregate size fractions, at all positions on the toposequence, decreased with decreasing aggregate size. In general, convex upper slopes had lower contents and amounts of organic C compared to lower concave areas. This study provided benchmark levels and patterns against which changes resulting from imminent urbanization can be measured.