Abstract
In acid sulfate soils, the heavy acidity is caused by the oxidation of sulfate, mainly pyrite (FeS2). In the primal acidify stage chemical and bacterial acidify work together. These bacteria (Thiobacillus ferrooxidans, Thiobacillus thiooxidans) have a huge role as a catalyst. This studies were examined the effects of drying on bacterial acidification, mainly on Thiobacillus ferrooxidans, and the formation of iron in the soil by the incubate experimentation. Five water content stages were set (1.30〜0.25kg/kg) by drying process in the incubator at 30°C for water adjustment. After the treatment, these samples were contained in the each bottles and started to culture at 30°C. Thiobacillus ferrooxidans propagated rapidly in the water content of Liquid Limit (LL)〜Plastic Limit (PL). Near the water content of PL, the propagation of the bacteria became slow, and they became decline near by the water content of Shrinkage Limit (SL). Amorphous - free - iron increased at the primal of acidification and changed for crystallized - free - iron. Around SL, the water content that the soil pH was stable, the propagation of the bacteria became slow, and the formation of iron became stable. In the range of water content 1.00〜0.70kg/kg (LL〜PL), the samples acidified strongly.
