Emperor Kangxi rewarded those who reclaimed wastelands, provided large sums of money for water conservancy projects and reduced the land taxation during his 60-year's reign, which greatly stimulated the recovery and development in agriculture of the Qing dynasty (1644-1911). Emperor Yongzheng followed his father '(Emperor Kangxi) footsteps and continued to encourage agricultural industry. The social economy was very prosperous during the reign of Emperor Qianlong, so the later historians called this period "The Golden Age of Three Emperors".
Large wasteland was put under the plough in the first 100 year of the Qing dynasty, with the national farming land covering an area of 5,260,000 hectares in the 18th year (1661) of Emperor Shunzhi's reign, which increased to 8,510,000 hectares and 17,250,000 hectares in the 61st year (1722) of Emperor Kangxi's reign and 3rd year (1725) of Yongzheng's reign respectively. With the output of grains increasing year after year, the number of population had reached 360,000,000 by the 3rd year (1725) of Yongzheng's reign, and the high-yielding sweet potatoes planted in Fujian and Zhejiang provinces had spread to the Yangtze River area and the Yellow River area. The planting area for industrial crops had also greatly been expanded, including tea, cottons, sugarcanes, tobaccos and mulberries, most of which became commodities in the Qing dynasty.
The number of farmers who specialized in planting vegetables increased greatly in the Qing dynasty, some of whom planted cucumbers and leeks in winter with the help of tunnel greenhouses, gaining more and more profit. With the cotton-planting prevailing across the nation in Qianlong Period, the cotton-planting area took up 4/5 of the total area in Hebei Province, and the sugarcanes were widely planted in Guangdong Province and Taiwan, while the tobaccos were widely cultivated in shandong Province, Zhili and Shangyu, all of which provided more raw materials for further development in handicraft industry.
Some plants imported from South American also contributed a lot to the increasing number of population in the Qing dynasty, including maize, sweet potatoes and potatoes, which had begun to grow in China from South America via Southeast Asian Countries since the Ming dynasty. The planting, storing and processing method of sweet potatoes was fully described in the Agriculture Encyclopedia written by Xu Guangqi from the Ming dynasty (1368-1644), which enjoyed a high reputation in the filed of agriculture, and the planting method of sweet potatoes was perfected in Qi Min Si Shu written by Bao Shichen from the Qing dynasty.