Pyrite Oxidation and Plant Responses to Acidic Sulfate Soils

Acid sulfate soils are acidic, contain high levels of Al and Fe, which can be toxic to plants, and are low in plant nutrients. Acid sulfate soils are marine deposits containing sulfidic materials (pyrite), have a sulfuric horizon, jarosite spots, and contain neutralizing materials in the form of carbonates or other exchangeable bases. The development of acid sulfate soils for agriculture is hampered by the presence of pyrite layers. Pyrite (FeS2) oxidation in acid sulfate soils occurs when the pyrite layer is exposed to oxygen, producing sulfuric acid that significantly lowers soil pH and releases harmful ions. This condition seriously inhibits plant growth due to heavy metal toxicity and nutrient deficiencies. This article discusses pyrite oxidation and plant responses to acid sulfate soils by reviewing various published scientific articles and various background studies. This paper highlights the chemical characteristics of acid sulfate soils, the mechanism of pyrite oxidation, factors influencing pyrite oxidation, acid sulfate soil conditions due to pyrite oxidation, and plant responses to pyrite oxidation. The oxidation of these compounds causes the soil to become acidic, with metals and bases dissolving, resulting in a soil impoverishment. The oxidation of pyrite with oxygen in acid sulfate soils occurs in several stages, encompassing chemical and biological reactions. Micronutrients, SO2, Fe2+, H2S, Al3+, and organic acids are released as a result of pyrite oxidation. These substances can act as toxins to plants, disrupting metabolic processes and causing damage.