Land use effects on the stocks of soil organic carbon (SOC) generally focus on the topsoil. However, while subsoil horizons have lower concentrations, they contain a significant amount of SOC, which may be more strongly protected than that in the topsoil layers. Analysis of SOC storage must therefore include the whole profile in respect of climate change mitigation. Humic soils in South Africa have high organic C in the A horizon, while the amounts of C stocks through the whole profile depth are unknown. This study was conducted at six sites in KwaZulu-Natal Province to determine the effect of land use and site factors on C stocks, texture, pH and extractable Al and Fe concentrations and their vertical distribution to 100 cm in soils with thick (>45 cm) and thin humic A horizons. The land use at some sites had been changed from uncultivated grassland to maize and cultivated pasture and at others from uncultivated forest to sugarcane farming. Clay soils had C concentrated in the topsoil while in those with coarser texture more C accumulated in deeper layers of the soil profiles. Although soil C stocks in the surface layers were reduced by cultivation, land use did not significantly affect the overall C stock (0-100 cm) at all sites. The high contents of extractable Fe and Al encourage the stabilisation of the soil C and were more important than the effects of either land use or other site factors.