Abstract
An attempt to improve the growth of oil palms on a Malaysian acid sulphate soil by leaching the soil intensively for five year was unsuccessful; the acidifica-tion of the soil was intensified, the condition of the palms deteriorated, and at the end of the period the soil still contained considerable reserves of unoxidized pyrite. Flooding the pyritic horizon by blocking the drainage channels caused a rapid improvement in the appearance of the palms, and 16 months after raising the water table the yield increased from 5 to 7 t/ha to more than 17 t of fresh fruit bunches per hectare. With appropriate use of fertilizer, yields a good as those on non-acid sulphate soils can now be obtained. An acid sulphate soil of the Sedu series contained bacteria resembling those found in similar soils elsewhere in the world, in that they promote the oxidation of pyrite by catalysing the atmospheric oxidation of pyrite. Experiments with oil palm seedlings grown in non-acid soil overlying acid sulphate soil showed that whereas the roots did not penetrate the freely-drained acid layer maintaining the acid soil in a flooded condition permitted root growth as extensive as in a freely-drained non-acid soil.
