Abstract
Borneo is the third biggest island in the world. It is under the tropical rain forest climate and most of the land is covered with lowland dipterocarp forests, where soil properties are mainly determined by the parent materials (Tertiary sand stone and shale) and topography. The red yellow podzolic soils by the Malaysian soil taxononly, Acrisols by the FAO-UNESCO classification, or UItisols by the US soil taxononly are widely distributed on the hilly land, while peat soils and alluvial soils are distributed in the lowland. Some arenacious soils are found in between hills and lowlands, where white coarse silicious sands are accunlulated (kerangas) and hold the kerangas or heath forests.
Soil nutrients in the forest soils were not always partialized on the surface soils as was often pointed out for the tropical forest soils. The rate of nutrient partition to the surface soils (5 cm / 70 cm) is almost equivalent to those found in the temperate forest soils of Japan. Land use capability is mostly determined by the slopes and subdivided by the soil acidity.
The shifting cultivation is one of the nlajor agricultural practices in Borneo island. Compared with the oil palm plantation and pepper field, rice cultivation on the sloping land without any plowing causes less soil erosion. Thus, sustainability of shifting cultivation is more than that of oil palm and pepper cultivation. However, considering the cash crop cultivation of the local people, a well organized agroforestry system should be introduced to protect against the severe soil degradation on the sloping lands.
