A History of Salt Making in Ibusuki
In an era of salt packets and low-sodium potato chips, it is easy to forget that salt is a vital nutrient and a staple ingredient in food cultures across the globe. In Japan, as in countless civilizations throughout history, salt has held huge economic, cultural, and historical importance.
Japan lacks the natural rock salt or salt flats that have provided salt in other regions of the world. Despite this, Japan has produced salt for about 3,000 years. The earliest method is thought to have used a simple cone-shaped earthenware vessel filled with a mixture of seawater and salt collected from seaweed fronds. The water would be boiled off, leaving the salt adhered to the inside of the vessel, which was easy to store and transport. Remnants of these vessels have been found at several archaeological sites in Kagoshima. Over time, superior methods of collecting salt were developed, enabling salt production on an ever-larger scale.
In Ibusuki, historical records indicate two villages with salt industries that date to the Edo period (1603–1867) or earlier. These villages used a salt pan method, in which buckets of seawater were poured onto stretches of sand. The seawater evaporated in the sun, becoming a highly concentrated salt brine that could be collected with large rakes. The brine was then boiled in an iron vat to cook off the remaining moisture, leaving the salt.
Prior to modern industrial salt production, salt commanded both economic and political power. To boost domestic salt production, additional salt fields were created using reclaimed land. They took the form of large salt pans that would naturally flood at high tide, replenishing the stock of seawater. Three such large-scale land reclamation projects were carried out by 1830, indicating the sheer value of salt at the time.
With the outbreak of the Russo-Japanese War in 1904, the Japanese government established a monopoly on salt to fund the war effort, and private production was no longer allowed. To foster the newly state-run industry, the government promoted the development of more efficient salt production methods.
In Ibusuki, where abundant hot springs are a source of plentiful heat, a researcher named Kurokawa Eiji began to explore whether geothermal energy could be used for salt production. In 1922, he was able to establish a reliable method. During World War II (1939–1945), salt imports decreased, and the government monopoly was lifted in 1942. Small-scale production was again permitted, and the hot-spring-based method spread. A small factory built in Yamagawa, near Fushime Beach, operated until 1964. Its buildings no longer survive, but the salt fields have been preserved as a testament to this unconventional salt-making process.
By the 1960s, industrialization had reached the salt manufacturing industry. A new method took advantage of the relationship between air pressure and the boiling point by evaporating salt brine in a low-pressure vacuum tank. This was found to use far less energy than other industrial methods, and a factory modeled on this vacuum process was opened in 1959.
These rapid advances in salt production technology led to a nationwide surplus, and the government tightened its monopoly once again. Small-scale salt manufacturers were forced to close, including in Ibusuki, where salt factories were shuttered in 1964. The government monopoly on salt production was maintained until 1997, but salt producers in Ibusuki are bouncing back, once again harvesting the life-giving mineral from the abundant seas.
