After a peat swamp forest has been cleared and drained, the peat soil is still unsuitable for agriculture, because peat soil is nutrient-poor and acidic (pH 3 - 4). To make the soil suitable for agriculture, the pH has to be neutralised and nutrients added. Pests and plant diseases also have to be removed. One method is to use chemicals such as limestone to neutralise the acidity, as well as fertilisers and pesticides. This method costs about Rupiah 30 - 40 million per hectare. Alternatively, fire is used to clear the plant material left over from logging. The fire kills pests and the resulting ash serves to fertilise the soil and neutralise the acidity. This method costs Rupiah 2 million per hectare.
