Studies on the Subsoil Improvement of Sea Bottom Polder based on the Analysis of Salt and Ion Behavior in Clayay Soil

1986 Fiscal Year Final Research Report Summary

• Project/Area Number: 60560248
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: 農業土木
• Research Institution: Okayama University
• Principal Investigator: AMAYA Takao Faculty of Aqriculture, Okayama University, 農学部, 講師 (80033265)
• Co-Investigator(Kenkyū-buntansha): MITSUNO Toru Faculty of Aqriculture, Okayama University, 農学部, 教授 (10026453)
• Project Period (FY): 1985 – 1986
• Keywords: Sea bottom polder / Gypsum dressing / Subsoil improvement / Cation exchange reaction / Physico-chemical properties of soil / 除塩

Research Abstract

The Fieid studies and laboratory experiments about a process of subsoil improvement after gypsum dressing into Kasaoka polder had been carried out. The results are as follows;
1. The field study showed the decrease of diffusion double layer and increase of free water because of the exchange reaction of adsorbed sodium ion by calcium ion supplied from gypsum. Consequently, the dispersion reaction in gypsum mixed layer had controled and soil changed to floculation state. At the same time, the improvement of soil physical characteristics had gained.
2. It was showed that the sedimentation volumes of soils was most adequate judgment standard for the improvement progress of sodium clay with gypsum.
3. The progressive situation of adsorbed sodium to calcium ion had been pursued and investigated from 1985 to 1986. The gypsum was scatterd and mixed until 50cm depth in the end of 1984 and its quantity was calculated from rational equation of cation exchange reaction considering spatial variance. Accordingly, the exchange had progressed smoothly and the subsoil improvement was remarkable. Furthermore, the long-term decline of salt concentration had become clear.