Estimation of the age of establishment of the traditional shaded cultivation system in a tea plantation in Uji, Kyoto, Japan using soil analysis and sup(14)C dating
2019
Inoue, Y. (Nagasaki Institute of Applied Science (Japan). Faculty of Applied Information Technology) | Nakao, A. | Yanai, J. | Sase, T. | Konishi, S.
This study aimed to determine from soil-based evidence when the traditional shaded cultivation system that used rice straw and reed screens in tea plantations was established in Uji, Kyoto, Japan. A soil pit was excavated close to the tea tree that was considered the oldest indigenous species in the only surviving rice-straw and reed-screen tea plantation called “Uji Shichimeien.” The pedon, which represented Okunoyama tea plantation soils, was described and carbon contents and phytolith compositions were examined. Humin fractions were dated using AMS radiocarbon (sup(14)C) dating. The carbon content began to increase upwards in the soil at the Bw (sample no. 8)-AB (sample no. 7) horizon boundary, and it further incrementally increased above the AB (sample no. 6)-A (sample no. 5) horizon boundary. Phytolith remains, which originated from Oryza (including rice), were found in the AB horizon and such phytoliths increased upwards at the AB-A horizon boundary. However, the phytoliths originating from natural vegetation (excluding those from Oryza) decreased upwards from the AB horizon to A horizon. The AMS sup(14)C dating yielded calibrated dates (standard deviation of 2σ) of 1341-1396cal AD (probability=56.9%) with a median date of 1369 AD on the humins in the upper part (sample no. 6) of the AB horizon, and 1396-1440cal AD (probability=90.8%) with a median date of 1418 AD on the humins in the lowest part (sample no. 5) of the A horizon. Therefore, the traditional shaded cultivation system in the oldest existing tea plantation in Uji (the Okunoyama tea plantation) was estimated to have been established in the first half of the 15th century, and this was approximately 150 years before the second half of the 16th century that was previously inferred from data from historical documents.
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