As the saying goes: seven things to open the door, rice, salt, firewood, oil, sauce, vinegar, tea. For this reason, salt, the lord of all tastes, and the general of food, are the necessities of people's daily lives. Because of the preciousness and importance of salt, the feudal state used salt as a monopoly commodity, making it an inexhaustible source of wealth to enrich the national treasury. The Book of Han? The Chronicle of Food and Goods says: "The land rent is endowed, and the profit of salt and iron is twenty times that of ancient times." "The New Book of Tang? Food Chronicle Yun: "The endowment of the world, the salt is half." ”
First, the reason for the excavation of well salt: Sichuan salt shortage
Sichuan is located inland, not by the sea, not near the pond, therefore, does not produce sea salt and pool salt. At the same time, no salt wells were dug earlier, and no well salt was produced. There is a Daning salt spring in the eastern Sichuan region, as well as Zhongba in Zhongxian County, and other places, which flow out of the ground (light) brine from the ground, and at that time became a base for producing salt in Ba and Shu and supplied the people's food needs. Daning Salt Spring, also known as "Dragon Pond", was discovered by hunters chasing white deer, so it was named "White Deer Introduction Spring", located at the foot of Baoyuan Mountain in Wuxi.
In ancient times, brine "out of the mountains and sinuses", the spring source is very strong, like a waterfall, brine frying salt. Because of the convenience of taking halogen, the origin is very early, and salt production flourished in the Shang Dynasty. During the Song Dynasty, Daning Salt Spring has become a famous salt-producing area in Sichuan, showing a prosperous and prosperous scene. Therefore, it attracted the attention of poets and literati. The Southern Song Dynasty patriotic poet Lu You's Notes on the Old School (Vol. 5) wrote: "Shu eats well salt, such as Xianjing Daning, is like a large cave. "Song? Ma Duanlin's Literature Tongkao (vol. 16) says: "The salt wells of Daning and Fushun (i.e., present-day Zigong) ... The wells of Changning are all large wells. The same literature (vol. 180ー) also says: Daning supervises the production of salt, "the benefit of a spring is enough to travel in all directions." "The east of Mo Liang Shu is the Society of Land and Water" (ibid., vol. 167).
Daning Salt Spring is located in the east of Sichuan, close to the Yangtze River, which shows that at that time, in Sichuan, both economically and socially, it was in an important position. At the beginning of the Northern Song Dynasty, in the first year of the Taizong Duan Gong (988), Sichuan's salt production dropped significantly, the production was not enough, the salt shortage in western Sichuan, and the salt famine caused a big disturbance, so that merchants sold Daning salt to Chengdu and other places to sell.
Daning Salt Spring, is a natural source without labor, brine salty with the natural seasons change, affected by the atmosphere and surface rain, winter and spring early season brine salty, summer and autumn rainy season brine salty light. The annual production time is about 6 to 8 months.
Due to the long history, during the unification of the Qin state and the Shu period, the output of Daning salt and Zhongba salt in eastern Sichuan could not be queried, so it is not known today. At the beginning of the Song Dynasty, Daning Spring's salt production was a prosperous period, ranking among the best in Sichuan, such as Song Shenzong Xiningzhong (1069-1077), with an annual salt production of "more than four million catties". Taking this as an example, we can calculate the amount of salt used by the people in Sichuan during the Ba and Shu dynasties. Of course, due to the progress of society and the development of productive forces, the output of spring salt has changed successively, that is, the salt production in the early Song Dynasty does not fully represent the salt production in the Ba and Shu periods, but it can be glimpsed.
After the qin destroyed Ba and Shu, there was no more major war in Sichuan, and it was in a period of peace and stability, which was called "Shiping Daozhi" in history. At the same time, due to the large number of immigrants into Sichuan and the rapid development of social economy, the population growth was greatly stimulated, so after the Qin Dynasty, the population multiplied by about 1.6 million. Here, we can calculate that before the sinking of salt wells in Sichuan, the people relied on the supply and demand of Daning salt, if the annual production of salt in Daning is 4 million jin, and the population of Sichuan is 1.6 million, the average annual use of salt per person is 2.5 jin.
The shortage of salt, the people suffer from light food, even if the pool salt is transported from Shanxi, due to the geographical conditions of Sichuan Road, the road is long, the price of salt is expensive, and it is difficult for the people to buy.
Second, the excavation of the first salt well in China
In ancient times, Sichuan was sparsely populated, frequent floods and droughts, and backward economy, which was called "western secluded" in ancient times. During the reign of the Qin state in Sichuan, Li Bing made a significant contribution to the development of the "western remoteness". The completion of Dujiangyan has turned the original drought-prone area in western Sichuan into a rice granary with "fertile fields and thousands of miles", and the people have been able to eat enough. However, the people of Sichuan have long been short of salt and suffer from light food. Therefore, Li Bing opened a salt well and collected brine to make salt to meet the people's food needs, thus alleviating the people's lack of salt and eating lightly. Since then, salt wells have mushroomed in the vast areas of Sichuan, and salt is not only self-sufficient, but also surplus, and the remaining salt is also exported to some parts of Yunnan, Guizhou and other provinces. The ancestors of Sichuan began to end the history of relying entirely on natural salt springs and "salty stones" to obtain salt. A new chapter in the history of manual well sinking, brine mining and salt production has been created.
Regarding Li Bing's excavation of salt wells, there are controversies in the salt history circles, and there are three main opinions:
One opinion holds that the excavation of salt wells is accidental, that is, when the people dig wells, salt water appears, and salt wells are named; the other opinion holds that there is a certain close relationship between the Dujiangyan project and the excavation of salt wells in Sichuan, which are due to the increase in population and the large demand for salt, and the lack of food needs for Daning salt, salty stone salt, or pond salt transported from afar. We believe that it is no accident that the second and third opinions, that is, Li Bing's excavation of salt wells, is aimed at satisfying the people's urgent need for salt. At the same time, sinking wells has a certain internal relationship with water control.
In short, as far as the excavation of the Salt Well in Guangdu is concerned, it is not an isolated and accidental phenomenon, but is closely related to the geological conditions and excavation technical conditions in the area, mainly in the following three aspects.
1. The abundant buried underground brine in the western Sichuan Plain provides a material resource guarantee for the excavation of salt wells
According to the geological exploration results, in the Western Sichuan Depression of the Chengdu Plain, the tertiary and Cretaceous strata are endowed with rich mineral resources of brine, glauber salt and gypsum, of which the salt content of brine is about 100 g/ l. In some areas, the halogen layer is buried shallowly, and the depth is 20 to 30 meters. The unique salt and brine resources provided important material conditions for the advent of China's first salt well.
2. Li Bingzhishui found that underground brine had led the excavation of salt wells
Li Bing did Shu punctuality, greatly developed water conservancy, chiseled away from the pile, avoided the harm of foam water, passed through the Erjiang Chengdu, diverted water to irrigate the fertile fields, and made the Western Sichuan Plain "fertile and thousands of miles" and became a well-known country of heaven at home and abroad. Dujiangyan project is huge, majestic, in the process of construction, the implementation of the implementation, the adoption of "encounter bends and angles", "deep beach", "low weir" and other effective and practical technical measures, that is, the use of dredging and embankment at the same time. To this end, in the process of "cutting corners", "taotans" and "building embankments" of water diversion, it is also due to the excavation and excavation of rocks, which exposes the shallow underground brine water resources, such as Li Bing's new discovery of underground brine in the dredging of the Tsing Yi River project, and the history has clear records.
According to the Jin Dynasty Chang Xuan's "Huayang Guozhi? Shu Zhi (蜀志) says: In Nan'an County (present-day Leshan, Sichuan, around the Jiajiang River), the Qingyi River is also known as Moshui, and there is a "salt irrigation" on the stone beach, which is flattened by Li Bing. Northern Wei Di Daoyuan's "Notes on water classics" Yiyun: Jiangshui "southeast of Nan'an County, west of Nan'an County, hanging with beaches ... Ri salt irrigation, Li Bing so ping also. "Salt irrigation" is the natural salt spring, the outcrop of underground brine on the surface. However, because the rocky beach in the Tsing Yi River hindered the smooth flow of the river and was difficult to navigate, boats often failed, so Li Bing rectified the waterway and dug the rocks in the river to facilitate navigation and water diversion. For this reason, although there is a salt spring, this beach is still flattened, so it is called salt irrigation beach, that is, salt spring beach. Li Bingzhishui discovered groundwater and pioneered the excavation of salt wells.
3. Li Bing "knows the water vein" to dig a salt well
Li Bing was a well-known expert in water conservancy and sinking engineering during the Warring States period, he was knowledgeable, proficient in astronomical geography and "knowing the water vein", and led the people to successfully excavate China's first salt well.
Li Bing in the water, the new discovery of salt springs, that is, underground brine from the outflow of the surface, to people to convey information, to remind the west of Sichuan contains rich brine water resources, therefore, to the host and leader of water control at that time Li Bing with important enlightenment, west Sichuan is a treasure land, on the ground, dujiangyan was built, obtained huge water conservancy resources, the Chengdu plain with frequent water drought into a granary. At the same time, underground, there are also precious salt water resources buried, which can be dug into wells to fry salt with brine to alleviate the urgency of the Shu people's lack of salt and light food.
Therefore, Li Bing "recognized the water vein", that is, according to the geological conditions, investigated the distribution law of underground brine, and personally trekked through the mountains and waded through the water, explored the rocks and chased the valley, and recognized the brine vein. According to the folk experience of "relying on the mountains as wells, separating the ditches with different veins", the shallow underground halogen layer was finally found in Chengdu and Shuangliu in western Sichuan. At the same time, he creatively applied the technology of drilling wells in the Central Plains and promoted the use of iron tools, and purposefully excavated China's first salt well, the Guangdu Salt Well.
The advent of the Guangdu salt well opened the prelude to the production of well salt in China. Since then, Yanjing has developed rapidly throughout the province, with three counties in the Qin Dynasty and 18 counties in the Han Dynasty.
Third, about the way of early salt well production
Guangdu salt well is the earliest excavated salt well in China, due to the long history, this salt well has not been preserved, therefore, the shape of the halogen well, the structure of the well body, surface facilities, production methods, etc. are unknown.
However, we have corroborated it from the images of han Dynasty well salt production portrait bricks unearthed in Sichuan. With realistic, delicate and vivid artistic images, the portrait reproduces the process flow of well salt production in the Han Dynasty, providing physical evidence for the study of early well sinking engineering technology in Sichuan.
The portrait bricks show a salt well near the foot of the mountain in front of the left against the background of the mountains and forests, the abandonment of wild deer, and the firewood cutting. At the head of the well, there is a four-column double-storey frame (i.e., derrick) on the ground, and a stove to make salt is set on the right side of the salt well. It can be seen from the image that the salt well is circular, the diameter of the wellhead is about 2 meters, and according to the burial of the halogen layer under the ground in western Sichuan, it is estimated that the shallowest depth of the salt well is more than 20 meters. Obviously, its well shape is a new type of salt well designed by drawing on the advantages of ancient wells in the Warring States period.
The image can also be seen that the four-column double-storey brine building frame, slightly narrower on the top and slightly wider on the bottom, seems to be like a pagoda shape, measured according to the height of the person, the height of the building is about 8 meters. The upper end of the frame is a pointed roof, which is obviously a shape set up to shield rain and sunlight, and a certain pulley is installed on the lower horizontal wood, and a halogen rope is tied to the wheel, and a halogen barrel is suspended at each end of the rope. On two floors, four people work in two groups of about two, pull up the rope, alternate, coordinate the movements, extract the brine, and then pour it into a wooden container and fry it with a bamboo basket into a salt stove. The use of fixed pulleys to collect halogen, although it can not save effort, but changed the direction of the force, reduced the labor load, improve the efficiency. It is the application and development of the principle of water lifting in the Central Plains.
To sum up: Li Bing was an outstanding expert in well sinking engineering and water conservancy during the Warring States period in China, and he did many good things for the people of Sichuan when he was doing Shu Punctuality, but the main achievements left today are the construction of the Dujiangyan Project and the excavation of the Guangdu Salt Well. Due to the abundant underground brine in western Sichuan, a solid material foundation has been laid for the excavation of salt wells. Li Bing discovered shallow underground brine in the process of water treatment, and led the excavation of salt wells. At the same time, he was knowledgeable, proficient in astronomical geography, good at "understanding the water veins", and personally led the people to creatively apply the well drilling technology in the Central Plains in Chengdu and Shuangliu in western Sichuan, and successfully excavated China's first Guangdu salt well, which opened a precedent for China's well salt production.