The salt resources in Hedong Salt Pond were first used, and the method of "fishing" was first adopted: sun exposure, natural crystallization, intensive cultivation, and salt production was entirely dependent on natural forces. The location of Hedong Yanchi is one of the hottest areas in North China in summer, with the highest temperature of 42.6℃ and abundant light resources. The annual precipitation is about 520 mm, but the evaporation is as high as 2300 mm. With the help of the south wind, it is a prominent feature of Hedong Salt Pond. The south wind passes through Zhongtiaoshan Valley, and the wind force is strengthened due to the narrow tube effect, and it sweeps the salt pond violently, blowing away the water vapor generated during the brine drying, so that the sunlight can irradiate the brine more effectively, and the brine continues to evaporate, accelerating the precipitation of salt crystals. How violent is the south wind here? As can be seen from the following examples, in Chiyou Village (now called Changshou Village) near Yanchi Lake, the traditional northern style of sitting north facing south is no longer used, but must be built to sit south facing north to avoid the south wind.
Because salt crystals are naturally formed and contain impurities such as magnesium sulfate, such salt tastes bitter, so "bitter salt" was once another name of Hedong salt.
During the Eastern Han Dynasty, Hedong Salt Pond began to adopt the method of "ploughing and drying water". This method is to cultivate the boundary artificially, build a ditch next to the boundary, and introduce the pool water into the boundary through the ditch until the water evaporates and crystallizes into salt. At this time, the cultivation, watering and drying methods are still in the primary stage, and the brine is introduced into the saltworks without filtration, forming salt on the soil, so the obtained salt is still bitter.
In the Tang Dynasty, salt workers began to use fresh water and brine to dry salt. Because the temperature of fresh water is low and the temperature of brine is high, the original temperature of brine is adjusted to decompose impurities such as magnesium sulfate and sodium sulfate to form a "nitrate plate", and a crystallization cup is built on the nitrate plate, so that the produced salt is no longer bitter, the crystallization time is greatly shortened, and the salt can be formed in five or six days. This is an epoch-making change in the history of salt making. In the history of salt drying all over the world,
In the next millennium, Hedong Salt Pond has been playing an important role in the salt production in China. In the glorious period, the salt tax in this place alone accounted for 1/8 of the national fiscal revenue. By the middle of Qing Dynasty, due to the desalination of brine, the salt production capacity of Hedong Yanchi declined rapidly. With the progress of modern science and technology, the production and transportation costs of sea salt have been reduced, and Hedong Salt Pond has gradually withdrawn from the salt-making stage.
At present, Hedong Yanchi focuses on building a "sea of death" tourism brand, and newly developed tourism and entertainment projects such as black mud health preservation, floating in the dead sea and mineral spring spa have been sought after by many tourists. However, the "Chi Temple" on the bank of Yanchi, where incense was once flourishing, and the "Hedong Salt Hall" now, although of high historical value, have been neglected and neglected. It seems that between remembering history and enjoying reality, people choose the latter more.