In subsequent years, as a result of the consolidation of the sapric and hemic materials, the rate of subsidence is only 2 to 3 cm per annum. In Sarawak, a subsidence rate of 6 cm per annum has been reported for peat with a water table at 75-100 cm. Chemical characteristics Organic soils in the three regions are very acidic with very low pH values ranging from 3.0 to 4.5. In some cases where sulphidic materials are found within the profile, pH values can drop below 3.0. Variability in the CEC values of peat is due to the stage of decomposition and nature of the organic matter.
Peat soils have low exchangeable bases and base saturation values.
Micro-nutrients, particularly Cu, Bo and Zn, are also deficient. Iron is found to be high. Severe Cu deficiency of maize, cassava and oil palm on peat have been observed. This is because the sapric and hemic layers provide the necessary rooting medium and anchorage which is otherwise absent in the fibric materials. To obtain this profile morphology, the peat swamp must be drained to encourage decomposition of the peat and to enhance consolidation and compaction of the broken down organic materials resulting in the formation of the sapric and hemic layers.