Shigeo Ishikawa

Improvement of Leaching Methods for Acid Sulfate Soil

The area of acid sulfate soil (ASS) is distributed on a coastal plain in Southeast Asia. If improved, the area is useful for agriculture. One of major improvement methods of ASS is leaching with a large amount of fresh water. But in some case, it may be difficult to secure enough water. In this study, column experiments and a solute transport model, Hydrus-1D, were used for suggesting the most suitable reclamation method using minimum water. In column experiments, efficiencies of leaching, percolation and inundation, were compared. In addition, soil water quality in the field was measured at Banna Experimental Station in Thailand for estimating the difference between the result of the laboratory and field experiments. In this survey, soil water was collected from the area treated by an amendment and from the area without amendment. As a result, the sulfate leaching efficiency by percolation was better than that by inundation. From model calculation, sulfate transport was also estimated to be leached more efficienctly by percolation. A survey of soil water quality in the field showed similar results from the column experiment of using the percolation method.