Author: Hou Yangfang (Professor of History Department of Fudan University) now has a popular view that the unprecedented population growth and quantity in Qing Dynasty, and even economic development, are mainly attributed to American crops, and even the so-called "drought-resistant prosperity" is called "sweet potato prosperity", which is totally unfounded. In fact, until 1957, the planting area of corn and potato was less than 20% of the national grain planting area. -Hou Yangfang With the continuous growth of the total population, the population pressure of the Qing Dynasty has been increasing since the middle of the18th century. As early as the 1950s, He Bingdi believed that in the last quarter of the18th century, a thoughtful generation of China people had begun to be shocked by the obvious decline in living standards that they had become accustomed to in the first decades of this century. 0 1 population pressure in the prosperous period of kanggan, originally the granary of China, Jiangxi, Hunan, had only a small amount of surplus grain in good years, and since the middle of18th century, food prices have steadily increased. At that time, local officials and the central government believed that population growth was the most fundamental reason and realized the existence of population pressure. ▲ He Libing Emperor Kangxi has a clear understanding of population pressure. In the forty-eighth year of Kangxi (1709), the emperor said in "Gu Gu Shu": "There are many teeth for a long time." Even at a fruitful age, I am still worried about the lack of food for the people. "It has been 678 years since the reunification of the region, the people enjoy peace and the number of births has increased. Although the number of registered permanent residence has increased, the number of cultivated land has not increased. How can one person support several families? " Forty-nine years (17 10) said: "It is inevitable that people's livelihood will not be fully rich because they have been doing good deeds for a long time, increasing their household registration, not increasing land, not increasing production and not giving food"; Fifty-one years (17 12) said: "Those who have not lost the price of rice in the end have more and more teeth, and there are a large number of idle people. As for Jiangnan, as early as the thirty-eighth year of Kangxi (1699), Emperor Kangxi was surprised to find that although Jiangsu and Zhejiang ... have never let go of land tax since the age of twenty, please do so ... The way to take care of the poor is extremely thorough, but "people's livelihood is not as good as before." Emperor Kangxi has no reason to exaggerate the severe population pressure under his rule. As the peace situation continues and the population continues to grow, the population pressure will only increase. Except for the closed northeast, the cultivated land in China has basically been reclaimed. In the 13th year of Yongzheng (1735), the imperial envoy Cao wrote to me: "I have lived in Taiping for a long time and have many teeth. If I belong to cultivated land, I will be barren. In the thirty-eighth year of Qianlong (1773), the emperor thought that the inland of China had been reclaimed: "If there is arable land, only the land in Urumqi, Xinjiang can attract people to settle down. As for the mainland's reclamation, it is absolutely nothing, and provincial governors must not take this as a statement. Although Xinjiang is large, its arable land is limited, which makes it difficult to alleviate the huge population pressure. From the early Ming Dynasty to the mid-Qianlong period, the increase of China's total grain output was attributed to the expansion of cultivated land and the increase of single grain output, which played roughly the same role. However, when the cultivated land in China was reclaimed in the second half of the18th century, it became more and more difficult to increase the output of a single grain because of the law of diminishing marginal income, so a national population crisis came. Wang Shiduo, a contemporary, marveled at this: "There are many people, millet has been plowed at the top of the mountain, continent fields have been set up in the river, old forests have been opened in the river, and seedlings are deeply planted, which is not enough to support, and the power of heaven and earth is poor. "After the mid-Qianlong period, the growth of the total grain output in China began to be lower than the population growth rate. Even with the cold climate, the increase of disasters, the destruction of water conservancy facilities and the consumption of soil fertility, the single grain output began to decline, and the people's living standards declined with the continuous decline of per capita grain output. China has been facing all-round population pressure, and the social and natural environment has deteriorated in an all-round way. In this context, the traditional economy has been difficult to maintain the living standards of hundreds of millions of people. If there is no comprehensive economic transformation, industrial revolution and qualitative leap in productivity, the economic crisis of the whole society and the subsequent political crisis will inevitably occur. During the Qianlong period, the social crisis brought by the population pressure caused by the popularization of American crops, Emperor Kangxi chose to reduce taxes, provide disaster relief, control rivers, build water conservancy projects, improve agricultural technology and frequently and vigorously raise multiple cropping index to deal with it. While inheriting the above measures, Emperor Qianlong and local governments at all levels began to promote the cultivation of American crops, with corn and sweet potato as the main varieties. In the fifty years of Qianlong (1785), Emperor Qianlong realized that "sweet potato can be used as food to resist drought, which will make people know its benefits, widely plant it and help people eat, and it is also one of the methods to prepare for famine". The biggest advantages of corn and sweet potato are strong adaptability and low requirements for land. They can be planted on barren hillsides in mountainous areas without competing for land with traditional rice and wheat. In order to encourage people to reclaim land and realize the goal of "no wild land" and "people can have enough to eat" of Emperor Qianlong, various preferential policies have been formulated at all levels, and the newly reclaimed barren hills and scattered plots will never be upgraded (tax-free forever), which are mainly used for planting corn and sweet potatoes. Under the impetus of the policy, corn and sweet potato were gradually popularized throughout the country: according to local records, in the 266 government-level administrative regions observed, 1776, 1 18 did not grow corn, and 1820 decreased to 72,185/kloc. 03 what's the matter? In the late Qianlong period, corn and sweet potato were popularized throughout the country, and the population continued to grow, which will exceed 400 million in the next 30 years. So, is there really a causal relationship between them? How much does corn and sweet potato affect the population growth in China? Chen Zhiwu quoted what Professor Gong Qisheng (actually Gong Qisheng, JamesKung) told us in the study of quantitative history, and thought that from 1776 to 195438+00, China was 14.438+02%. /kloc-from the beginning of the 6th century to the beginning of the 20th century, 55% of the grain increase in China was due to these three new crops (corn, sweet potato and potato). This is actually the result of the joint signature of Gong Qisheng and his students. In this paper, the government is divided into two control groups, corn planting and no corn planting, using statistical methods to infer the impact of corn on population, instead of using 1330 county chronicles as claimed by Chen Zhiwu. Chen Zhiwu said: According to the time points of 1776, 1820, 185 1, 1890, 19 10, the counties that adopted corn in various periods. The population density of maize increases by 5%-6% every ten years. After the verification of various rigorous calculation methods, they came to the conclusion that it was corn that drove the population growth in China, not the pressure of population growth that forced China to introduce corn and sweet potatoes. However, as mentioned above, a large number of historical materials from various information sources show conclusively that as early as forty-one years ago (1776), the population pressure in China was very common, and it became more and more serious, and it became the knowledge of the ruling and opposition parties. Because of this, it forced * * to popularize and improve corn and sweet potato, two American crops that are not suitable for China population, that is, with high population density. Chen Zhiwu's assertion, if established, will be an amazing discovery in China's economic history, but Gong Qisheng quoted the conclusion of Perkins' book Agricultural Development in China, both of which stated in their original texts: "In this long historical period, about 55% of the increase in China's grain output was attributed to the expansion of planting area", but it was not attributed to these three American crops at all, as Chen Zhiwu said. This mistake is also amazing. " China 14. 12% population growth is caused by corn? The answer is suspicious. Because local chronicles only record the presence or absence of corn planting, but not its planting area and output, there is no calculation method to accurately calculate the impact of corn on population growth based on the presence or absence. The impact of American crops should not be exaggerated. So how much influence did American crops, such as corn, sweet potatoes and potatoes, have on the population of China in the Qing Dynasty? The output of various food crops in the Qing dynasty was not counted and could not be estimated. Fortunately, there were corresponding statistics in the early years of the Republic of China. 1914-1918, planting area of corn and potato (including sweet potato, potato and taro originated in China, etc. ) accounts for 7.2% of the total cultivated land area in China, and the sum of their output accounts for 7.67% of the total grain output; In the 1920s, the total output of corn and sweet potato, including all kinds of taro originated in China, only accounted for 9% of the national grain output. Since the planting area of American crops such as corn and sweet potato has been growing steadily and rapidly for more than 65,438+000 years from the mid-Qing Dynasty to the mid-20th century, if we push forward, the proportion will only be lower. According to Wu Hui's estimation, the total output of these two crops in the middle of Qing Dynasty (from the end of Qianlong to Jiaqing) only accounted for 4.63% of the national grain output, which may be very high. Even assuming that corn, sweet potato and potato are all used as human food, their contribution to population growth in China is extremely limited, even insignificant before the end of Qianlong. Therefore, American crops had little influence on the huge population growth and breakthrough of 200 million, 300 million or even 400 million in Qing Dynasty, while traditional crops were still used to feed hundreds of millions of people in China. In fact, until 1957, the planting area of corn and potato was less than 20% of the national grain planting area. There is a popular view that the unprecedented population growth and quantity, and even economic development in the Qing Dynasty, are mainly attributed to American crops, and even the so-called "Kanggan Prosperity" is called "Sweet Potato Prosperity", which is totally unfounded. I have no objection to the quantitative study of history. In fact, the basic research method of my doctoral thesis (the theme is population in Ming and Qing Dynasties) and China Population History (Volume VI) is measurement. However, quantitative research has several necessary premises: the background should be comprehensive and in-depth, the limitations of data should be clear, and the sources should be reliable, which is particularly important for the study of China's traditional era. There are a large number of people over the age of 100 or even 200 in the official Yellow Book of the Ming Dynasty. In the Qing Dynasty, "Ding" has three different units and meanings, and the "mu" of cultivated land in the Ming and Qing Dynasties is far from the actual area ... If we do quantitative research on them indiscriminately, I am afraid that the more complicated the method is, the more difficult it is, and the farther the conclusion is from the fact. Doesn't this quantitative research violate the original intention of seeking truth? The unprecedented population in Qing Dynasty was due to the introduction of high-yield American crops, such as sweet potato and corn, because they were not only high in yield, but also drought-tolerant, and could be planted in barren and rugged mountainous areas where traditional crops were difficult to grow, thus expanding the crop area and increasing the total grain output of the country. This view can be applied to the future. According to the statistics of the fifty-four years of Qianlong, the total population of the country has exceeded 300 million. The popularization of American crops in the country began at the end of Qianlong, and Emperor Qianlong himself actively advocated and encouraged it. The premise of human survival is to have basic food to sustain life, so this unprecedented population in China history actually means unprecedented food production, and the economic development of Qing Dynasty is the highest peak of traditional China. This article is taken from Hou Yangfang's "Prosperous Western Han Dynasty" and "Prosperous and Healthy Feeling". Thanks to CITIC for publishing and generous authorization.