China's ancient traditional agriculture utilized what ecological principles

Before the Sui and Tang dynasties, China's economic center of gravity was in the Yellow River basin, a region that was originally swampy and marshy, and where agriculture was often developed by first digging ditches and moats to wash away the alkali and form raised beds of farmland. This kind of ditch and moat farmland was associated with the use of scythe, coupled plowing and the well-field system. After the Warring States period, with the changes in the natural landscape and the decline of the well-field system, low-bordered farmland with flat-turned plowing was introduced instead. Large-scale irrigation was also developed, but dry farming was still the main part of agriculture in the north. In addition to some mountainous areas in the south, the implementation of slash-and-burn cultivation, has long operated in the relatively low areas of paddy fields, but to varying degrees for a longer period of time to preserve the habit of hydropower hoeing. After the Sui and Tang, the center of economic gravity shifted to the south. Population increase and land annexation prompted people to the mountains and waters development, the emergence of fields, terraces and polder, Tu Tian, Shatian, shelf fields and other forms of land use. The population surge in the Qing Dynasty, resulting in a pattern of high population and low arable land, a large number of people flocked to the southeastern coastal islands, southwestern border, barren mountains in the interior and traditional pastoral areas of the Northeast, Inner Mongolia, Xinjiang and so on, which led to the further development of these areas. In the process the experience of transforming and utilizing barren mountains, mudflats and saline land was created, but it also damaged the forest resources and the environment for pastoralism.

While expanding the area of cultivated land, the main way to develop agriculture in ancient China was to improve the utilization rate of cultivated land. Since the Warring States period, the continuous cropping system has gradually replaced the leisure cropping system as the main planting system. Repeated planting in the local area has long appeared, but the larger promotion began in the Song Dynasty in the south of the rice and wheat a year two-maturing system, since the Ming and Qing dynasties, Jiangnan's double-season intercropping rice and double-season rice development faster, South China and Taiwan and appeared in a year three-maturing account. In the north, the two-year triple-cropping system has also been developed. A variety of crop rotation and multiple levels of intercropping, etc., to adapt to the needs of continuous replanting has also been created. High-yield crops such as rice, sweet potatoes, and maize helped to feed a larger population, and the population pressure promoted the emergence of more intensive land use.