津波を受けた水田土壌塩分の経時変化

Abstract

A field test was conducted in a tsunami-affected paddy field in Natori city, Miyagi prefecture to understand temporal changes in soil salinity over the past 27 months and to collect information about the desalinization in the near future. Vertical profiles of the soil salinity and water content were obtained by TDR and four-electrode sensors installed down to a depth of 0.6m below the paddy soil surface near our micrometeorological station. Salt mass in the soil up to 200mm from the soil surface varied greatly due to eluviation of salt from the soil by rainfall and due to re-adsorption by the drying of the soil surface. Salt movement in the soil deeper than 200mm was, however, hardly observed for about one month to two years. Cl- concentration in the soil was reduced to below the allowable concentration of rice planting about 400 days after the tsunami attack by runoff from the paddy field due to rainfall. It is seen from the above results that the salt removal of saline soil surface layer of 200mm is effective for the desalinization.