China Table of Contents
In 1987 the main method of weed and insect control continued to be labor-intensive cultivation. Fields were carefully tended, and a variety of biological controls, such as breeding natural enemies of crop pests, were used. Production and use of chemical herbicides and pesticides increased rapidly from the mid-1950s to the mid1970s , but output fell subsequently by more than half (to about 200,000 tons) because the products were relatively ineffective, expensive, and highly toxic. Chemical pesticide use, therefore, was low compared with use in other countries.
Improved seed varieties have contributed significantly to improving crop yields. Highly fertilizer-responsive varieties came into use beginning in the mid-1960s. These were comparable to those developed outside China but were adapted to the shorter growing season imposed by multiple cropping. Their extensive use has complemented the large increases in fertilizer use and the increase in irrigated area. In the mid-1970s farmers began to plant hybrid rice, claiming yield increases of more than 20 percent. Hybrid rice is not used elsewhere because of the amount of labor it requires, but more than 6 million hectares of it were planted in the mid1980s , accounting for 20 percent of total rice area. The China National Seed Company was established in 1978 to popularize improved seed varieties; it exported Chinese vegetable seeds and imported improved grain, cotton, forage, and oil seeds. About 5 percent of China's arable land was being used to raise seed in the mid-1980s, and the company operated more than 2,000 seed companies at provincial, prefectural, and county levels.
Data as of July 1987