- Japanese: 塩 (shio)
Salt was a major product of many regions of premodern and early modern Japan, and had a variety of important uses, including for the preservation of food. Salt was also a prominent tribute good paid to the Imperial Court in the Nara and Heian periods, and a major form of tax payments to the Tokugawa shogunate in the Edo period, especially from those regions which were not particularly strong in rice production.
The "production" of salt by extracting it from seawater is mentioned as early as in the Man'yôshû (8th c.), and was probably practiced since considerably earlier than that. In fact, archaeological evidence suggests that seawater was being intentionally evaporated to produce salt as early as the Late Jômon period, and that the salt was even being transported, or traded, further inland. Jômon people may have also extracted salt from the soil. Salt production from the sea seems to have dropped off dramatically shortly before the beginning of the Yayoi period, however.
Though Japan can be quite hot, and quite sunny in many regions in the summer, most regions are also quite humid, and so sunlight alone is generally ineffective for extracting salt from seawater. Since classical times, therefore, water was typically boiled over a fire, in earthenware pots; iron cauldrons are known to have been used in the Inland Sea area since at least the 8th century. Seaweed immersed or dipped in seawater and then shaken or squeezed over the pot was often used to produce even more salt in a given batch.
Seashore women hauling buckets of water, collecting seaweed, and/or boiling the water in pots on the shore are a common trope seen in classical Japanese poetry, and especially in certain classical stories such as the Tales of Ise and plays based on them. One of the most famous Noh plays featuring such characters is Matsukaze, in which the ghosts of two such women pine for the aristocratic man who once visited them while he was in exile.
Beginning in the early medieval period, people in some regions began to spread seawater on sandy hillsides called agehama, where it could be dried in the sun. Though this caused the salt to get mixed in with the sand, and still needed to be dissolved and boiled to separate it out again, this process somehow was more efficient, or more effective, producing more salt than simply boiling one pot at a time on the seashore. In the 17th century, this process was refined even further, with the advent of irihama, artificial tide pools created along the seashore. Water poured in at high tide, and was captured and dried to yield the salt.
All of these processes consumed a lot of firewood, however, and so were not particularly efficient in that respect. By the 18th century, coal began to be used to help fuel the process, dramatically improving the profitability of the process.
- Arne Kalland, Fishing Villages in Tokugawa Japan, University of Hawaii Press (1995), 91-92.
- Tatsuo Kobayashi, “Nurturing the Jomon,” in Jomon Reflections (Oxford: Oxbow, 2004), 81.