其他摘要：Suwanose Island was once uninhabited for 70 years due to a volcanic eruption in 1813. Recently, the island population has gradually increased to 70–80 under the policy of promoting immigration with agricultural activities. It is significant to obtain information regarding the soil properties of this island in relation to agricultural land use. In this study, we carried out a soil survey on cultivated land, grazing land, bamboo forests, and outcrops on the island. Soil pH, electrical conductivity (EC), NH4–N and NO3–N contents, exchangeable K content, cation exchange capacity (CEC), humus content, phosphate absorption coefficient, and particle size distribution were examined to evaluate soil fertility and to classify soil type.The soils of agricultural areas on Suwanose Island were mainly classified as “tephric Regosols” and partly as “vitric (immature) Andosols,” and the buried soils beneath the 1813 volcanic eruption deposits were “vitric Andosols” according to the Comprehensive Soil Classification System of Japan, First Approximation. The chemical properties of the soils studied had weak-neutral pH and low phosphate retention, which indicated a positive capability for agricultural land use, although the formation of typical Andosols will be difficult as long as the intermittent ash fall continues due to the current activity of the Otake volcano. The analytical results suggested that soil amendments such as green manure supply, as currently practiced to a limited extent in a mandarin orange orchard, may improve soil fertility. The buried soils with a formation age estimated at 200–600 years ago, had a relatively high CEC and high clay content. The utilization of the buried soils by land grading was suggested as a countermeasure to expand the agricultural area on Suwanose Island.
关键词：諏訪之瀬島;土壌分類;地力;農業土地利用
其他关键词：Suwanose Island;agricultural land use;soil fertility;soil classification
