干拓地土壤に関する研究 (第17報) 伊勢湾台風による冠潮塩害地土壤について

This study was conducted to determine some characteristics of salted soil formed by flooding of sea water at the typhoon "Isewan", occurred on Sept. 26, 1959, with special reference to the effect of salinity and sulfide on growth of rice plant. A survey was carried out on May 1960, on Mie Prefecture and soil samples were collected and investigated. By this survey and investigation, the following points were made clear: 1. A considerable difference in chloride content and electric conductivity was found among soil samples. It was observed that, in general, the surface soil before leaching contained a large amount of soluble salt but most of surface soil in which the leaching was accomplished showed a marked reduction of salinity, with less than 4 millimhos/cm electric conductivity. 2. The texture of sea-mud deposits was very fine, containing more than 30% of silt and 10% of clay, and an appreciable amount of H2S was produced when incubated in water-logged condition. 3. Most of the soil of this region had the common characteristic of halogenetic soil, containing relatively large amounts of exchangeable mono-valent cations and magnesium. 4. Some of the salted soil contained appreciable amounts of oxidizable sulfur and the pH values of the soil became extremely acid after oxidation with H2O2. 5. A considerable difference in content of H2S and readily soluble and HCl soluble sulfide was found among these samples of soil. The experiments have indicated that an addition of rice-straw to salted soil in water-logged condition enhanced the rate of formation of H2S and sulfides in soil greatly.