Decreasing pyrite content and acidity on potential acid sulphate soil of south kalimantan by leaching-oxidation

Pyrite (FeS2) is a secondary mineral attribute of acid sulphate soil that is highly insoluble and can produce a high concentration of ferrous ions and sulfuric acid (H2SO4) which leads to extreme acidity of soil and water (pH<4). Leaching is one of the techniques that can be used to reduce acidity in acid sulphate soils. The objective of this research was to determine the effect of leaching and oxidation on decreasing pyrite content and acidity of a potential acid sulphate soil. The study was conducted in a greenhouse in Indonesian Swampland Agriculture Research Institute (ISARI), Banjarbaru. The experiment used a Randomized Complete Design (RCD) with 9 replications. The treatments were wetting of the soil followed by drying for 7 and 14 days, in a continuous cycle for 6 months. The results showed that pyrite content of the acid sulphate soil decreased faster with 14 days of treatment compared to the 7 days treatment. The decrease was 80.68 and 70.08, for the 14 and 7 days treatment, respectively. The quantity of titration acidity (sums of available H+ and Al3+) decreased by 14.90 cmol(+)kg-1 and 15.23 cmol(+)kg-1 respectively. It can be concluded that the longer the pyrite is exposed to air and followed by leaching, the more pyrite was oxidized and titration acidity can be removed. © 2020 Taylor & Francis Group, London.