Pedology and Edaphology of Acid Sulfate Soils in Hokkaido

Abstract

Since the 1980's, damages derived from acid sulfates soils which appeared due to large scale cutting of soils have occurred in Hokkaido. A report on the classification with age or formation factors, properties, and distribution of these soils is introduced. Reports on countermeasures against these soils are also introduced. Subjects on the Japanese soil classification system for acid sulfate soils are described. 1. Acid sulfate soils appearing in Hokkaido are classified by origin of contained sulfur, namely marine deposit or volcano-geneous activities, formed age, and so on. 2. Vegetation on cut slopes of acid sulfate soils was successful by the neutralization method with CaCO_3, but failed by the impermeable method with a sheet of 1 cm thickness. The cost of the neutralization method is cheaper than traditional methods. 3. Countermeasures for acid sulfate soils damage caused by the consolidation in paddy fields were investigated. 4. Causes of drainage pipe clogging in the Mt. Tokachi mud flow distributed area, which consist of volcano-geneous acid sulfate soils, were clarified. Countermeasures using rockwool (calcium silicate) as filling material in ditches of tube drainage were successful. 5. The Japanese soil classification system for acid sulfate soils in Hokkaido seems to be insufficient.