The Yangtze River Basin in China and its south area are the origin of rice cultivation. There are not only records of wild rice in history, but also the distribution of wild rice today. More importantly, more than 80 Neolithic rice remains were found here, from 1000 years ago to 45,000 years ago. And with the deepening of archaeological discoveries, the number of rice remains is still increasing, and the age is still pushing forward. At present, the well-known Neolithic rice remains have been excavated, including: Wannian Xianren Cave Site in Jiangxi, Diaotongyuan Site, Pengtoushan Site in Lixian County, Hunan Province, Yuchanya Site in Daoxian County, Hemudu Site in Yuyao, Zhejiang Province, Luojiajiao Site in Tongxiang, Caoxieshan Site in Wuxian County, Jiangsu Province, and Jiahu Site in Wuyang, Henan Province.
Although rice originated very early, it was unknown for a long time and even excluded from the "five grains". The main reason is that the Yangtze River valley and its south area, which produce rice, are in a relatively backward state for a long time, and the rice cultivation techniques are relatively primitive. History books are often summarized as "fire ploughing puddles". The so-called "fire tillage" means burning weeds in the field with torches before planting rice. When seedlings and weeds grow at the same time, they are put into water. Because in the case of flooding, rice can still grow normally, but weeds are difficult to survive. Although this rice cultivation technique is primitive, it skillfully uses the characteristics that rice is not afraid of flooding. The phylogeny of rice grows in the flooded swamp, and its roots have schizogenic aeration tissue, which is the unique aeration tissue of swamp plants, that is, the passage to transport air from stems and leaves to roots. If the flooding is too deep and the breathing is blocked, it also has the effect of gas exchange. In addition, roots absorb water and nutrients when they are young, and the cell wall thickens after aging, which only plays a guiding role and prevents oxygen loss in the body. In addition, adventitious roots generally do not grow on stem nodes and tillering nodes of the main stem. It seems that in the case of excessive humidity or waterlogging, bud nodes will also take root, and potential cracks at the base of leaf sheaths will penetrate to the outside for absorption. In addition, the characteristic that rice internodes extend with the deepening of water layer is the biological basis that irrigation can drown weeds without harming rice seedlings.
Fire-ploughing and water-ploughing successfully use different reflections of rice straw under the condition of flooding to achieve the purpose of weeding, but it is a relatively backward rice cultivation technology, which is suitable for use when the land is vast, the population is sparse and the labor force is scarce. However, after the Tang and Song Dynasties, with the shift of economic center of gravity to the south and the increase of population in the south, Huogeng pond was replaced by intensive cultivation. Intensive cultivation techniques of rice fields in South China mainly include paddy field soil preparation techniques with tillage, harrowing and furrowing as the main body, sowing techniques with seedling raising and transplanting as the main body, and field management techniques with tillage and baking as the main body.
Paddy field farming and dry land farming may be common in many aspects, but some improvements have been made in farming tools to adapt to the characteristics of rice fields in the south. For example, the paddy fields in the south are generally smaller than the dry land in the north, so the original straight-axis plow is not flexible to use, so the Jiangdong plow appeared in the Tang Dynasty. Jiangdong plough is a kind of crankshaft plough, which is small and flexible, and can meet the needs of frequent ploughing when cultivating small plots of land. (Jiangdong Plough) Another example is that rice grows in water, and the depth of the water layer will have a great influence on the growth of rice. Therefore, the field surface is required to be flat. In this way, the horizontal depth can be kept consistent, and the area of each paddy field is small, except for natural reasons, because small paddy fields are easy to level off. In order to level the fields, a unique farm tool "Ying" appeared in Song Dynasty. The emergence of paddy field marks the formation of paddy field soil preparation technology in southern China.
The technology of rice transplanting first appeared in the literature of Han Dynasty. The May issue of "Four-person Moon Order" said: "It's the moon, but don't leave Daoqing until the last twenty days." "Don't eat" means transplanting rice. After the Tang and Song Dynasties, transplanting technology was widely used in rice production, and the corresponding seedling raising and transplanting technology was formed. The seedling horse that appeared in the Song Dynasty is a farm tool specially designed and manufactured for pulling out seedlings. The technique of cultivating healthy seedlings was also preliminarily summarized in the Song Dynasty's "Chen Fang Nong Shu", which pointed out: "If you want to grow healthy seedlings, you should plant them at the right time, use fertilizer reasonably in the right place, and be diligent in taking care of the province to avoid drought, drought, water, insects and animals." It is emphasized that only by mastering the key points of timely sowing, suitable land selection, reasonable fertilization, fine management and disaster prevention and resistance can good seedlings be cultivated. Transplant technology has been finalized at least in the Yuan Dynasty. The method is as follows: "Insert awn seeds before and after. When pulling out the seedlings, gently pull them out, and then wash the uprooted mud. About 80, 90 kinds of a small bunch, but every four or five kinds of a bunch, don't move your feet often. Just insert six strings and move once. " Insert six more clumps and move again; Insert one by one, and be sure to straighten it. "This method of transplanting rice has been used to this day.
After transplanting rice, it is transferred to field management. Paddy field management mainly includes fertilization, irrigation, ploughing and baking. In ancient times, the base fertilizer was called "bottom" and the topdressing was called "relay". For a long time, people have focused on using base fertilizer because it is completely reliable. "Shen Shi Agricultural Books" said: "The bottom is particularly important. At the bottom, although there are many floods, Miao Ken floats deep on the water and will not be submerged. Although planted late in dry years, it is vulnerable to attack. " However, in the Ming and Qing dynasties, people have also summed up a set of methods for safe use of relays. Xing Wu's Tales in the Ming Dynasty: "The old farmer in the lake said: Don't dump the manure too early, and it will shrink more than it shows in autumn. At the beginning of planting, it must be based on river mud. Although its strength is slow and long, it will be a little gray or vegetable cakes in summer, and its strength is slow but not fast. After the summer heat in autumn begins, it will be stronger and its ears will become longer. " Shen Shi Agricultural Books summarized a set of experience of "fertilizing according to seedling color". It is pointed out that "the next relay" means "when the seedlings are pregnant after the summer, when the seedlings are in Huang Zhi". If the seedling color is not yellow, you must not get off the relay. In the end, it won't be yellow and it won't go down. This fertilization method developed into the theory of "Huang San's Three Blacks" in 1950s.
Paddy field irrigation was first seen in the Book of Songs, "The pond flows northward and soaks other paddy fields". Measures were taken to regulate the temperature of water entering rice fields in the Han Dynasty. "Fan Sheng Zhi Book": "When rice is first planted, it is warm, and those who are warm are lacking, which makes the waterway straight, and it is hot after the summer solstice, which makes the waterway wrong." This is to adjust the water temperature of rice field by controlling the position of water inlet and water outlet. This method is still used in later generations. During the Song and Ming Dynasties, people calculated the water demand of rice. Song Wuyi's "Planting Art Must Be Used" quoted the old farmer as saying: "Rice seedlings are the first in beginning of autumn, watered every night, and the second in beginning of autumn is two liters." During the Ming and Qing Dynasties, the star "Wu Kai in the Heavenly Palace" said: "All young plants are full of vigor and vitality. If they eat three buckets of water early and five buckets of water late, they will die if they lose water. A liter of water will be missing when mowing the grass. Although the number of rice grains still exists, the rice grains will shrink and break into pieces when they enter the mortar. " Accordingly, the ancients concluded that rice was "particularly afraid of autumn drought". In view of this situation, "Shen Shi Agricultural Book" pointed out: "After the autumn of independence, there must be no shortage of water. If there is less water, the car will start until the rice is sown. Common clouds; Rice is as red as a warbler, and it is all supplied by water. " This is not only the need of drought resistance, but also the need of frost prevention. Otherwise, "if the weather freezes suddenly, the frost is early, and there is water in the field, the frost will not damage the rice." Where there is no water, rice will be wasted. "
Farming and baking fields appeared in the Northern Wei Dynasty. The Song Dynasty was further developed. The role of ploughing is not only weeding, but also "don't ask if there is grass, but also paddle by hand to ensure that the liquid is next to the rice roots." According to the uneven characteristics of rice fields, it is required to "spin dry" from bottom to top. Collect livestock water before the roof to avoid getting lost. Then it is rotated from the bottom, dried and rotated. "In order to meet the needs of farming, a plow claw was also invented in the Song and Yuan Dynasties. It was made into a palm shape with a bamboo tube and worn on the finger to avoid direct contact between the finger and the soil and reduce damage. In addition to hand farming, foot farming appeared in the Yuan Dynasty. When plowing, I hold a crutch in my hand, and pull the soil down with my toes, and get stuck under the roots of the seedlings, which plays the role of weeding, fertilizing and improving the soil. The Yuan Dynasty also created the method of plowing farmland. A plow is a tool, with nails nailed under the board and bamboo handles on it. When plowing, it can push the mud between ridges like a hoe, which can replace the hand plow and foot plow, and at the same time improve efficiency and reduce labor intensity. So far, the traditional rice cultivation method in China has been completed. The methods used in the Song and Yuan Dynasties have been used to this day.
Baking is mainly combined with ploughing. Generally, after ploughing, drain the water and bask in the sun. However, simply draining water will also drain the fertilizer water, so in the Song Dynasty, a method of digging ditches in the field (now called "scooping leakage" in rural areas of Jiangxi) appeared to bake the field, so as to control the moisture in local areas of the field and prevent the outflow of fertilizer water.
While improving farming techniques, people also improve crop yield through continuous seed selection and breeding. In Song Dynasty, early maturing and drought-tolerant Zhancheng rice was introduced to adapt to the cultivation in higher terrain areas. Zhancheng rice is named after its origin in Zhancheng County (now south-central Vietnam). It is characterized by small grains, no awn, early maturity, drought tolerance, random growth and high yield. Before the Song Dynasty, it was introduced to China and Fujian. In Song Dynasty, large and medium-sized auspicious symbols were introduced into Jianghuai Road and Zhejiang Road for five years (10 12) and four years (101), which promoted the development of local terraced fields and agriculture in Tian Gang. After the Southern Song Dynasty, it has become the main food for the general public. In the process of spreading, Zhancheng rice also differentiated many variation types suitable for local characteristics, which created conditions for the further rationalization of rice variety layout and the development of multiple cropping. When Zhancheng rice was introduced, yellow rice mainly appeared in low-lying and waterlogged lake areas. Judging from its pronunciation, yellow rice existed before the Tang Dynasty and even during the Northern Wei Dynasty, but it was only after the Tang and Song Dynasties that it really had a great impact on rice production. Yellow rice has the characteristics of waterlogging tolerance, and can still grow and bear fruit normally when the water level in rice field exceeds the actual needs. At the same time, it also has the characteristics of precocity, and the growth period is very short. It can plant and harvest a season of rice before the flood comes or after the flood recedes. These characteristics adapted to the needs of economic development and natural conditions after the Tang and Song Dynasties, especially the need to compete with water for land, which made it widely popularized. After several generations of efforts, the variety of rice has been increasing. There are 13 rice varieties in Guang Zhi, 24 in Qishu, 46 in Hepu and 35 in rice, and more than 3,000 rice varieties are regularly surveyed. Many varieties are the result of long-term planting and selection. They not only meet the needs of planting under different natural, technical and economic conditions, but also meet the needs of people's daily life.