Agroforestry and Crop System

China¨s intercropping and relay intercropping area (about 159%) is the largest in the world. The multiple cropping system is mainly practiced in the southeast and the middle and lower reaches of the Huanghe River with a temperate climate and sufficient rainfall and a quite long frost-free period. Some areas even keep frost-free all year round, with the rainy season and the hot season at the same period, and less cultivated land for supporting more people so that the multiple cropping system is beneficial. There are manifold forms of intercropping, relay intercropping, multiple cropping and rotation. The two-crop a year system of rice-wheat, rice-cotton, rice-sweet potato, and the rotation of rice-peanut, rice-green manure, and the double cropping of rice and three cropping rotation of rape are practiced in the middle and lower reaches of the Chanjiang River, with cropping intensity generally between 200% to 250%. The growing areas of winter wheat, cotton, corn, soybean in China are centralized in the lower reaches of the Huanghe River and the areas north to the Changjiang River, where two-crop a year system or three-crop two years system is practiced, with interplanting of corn in wheat and potato, intercropping of sesame in peanut and intercropping of black soybean in sorghum etc.

The distribution of crops in China is region specific. The Northeast is the centralized growing areas of corn, soybean, sorghum, sugar beet, where only one-crop a year system can be generally practiced because of the cold climate and short frost-free period. The Northwest is in the arid area and semi arid area, where one-crop a year system is generally practiced and three-crops two years system in small basin area, with spring wheat, corn, millet, highland barley, potato, beet, melon and fruit etc. as the major crops. The plain area of north China is in the warm temperate zone where two-crops a year system or three-crop two year system is practiced. This area is the major growing area of winter wheat, corn, cotton, peanut and tobacco because of the connected farmland, low elevation, quite sufficient heat and developed irrigation. The Liaodong Peninsula, the old river course of the Huanghe River, the areas of north China, northwest and southwest river course of the Huanghe River, the areas of the north China, northwest and southwest of China are the major growing areas of apple, pear, peach and grape. With abundant rainfall, various kinds of crops, large area of paddy field, intensive and meticulous farming, and high cropping index, the middle and lower reaches f the Chiangjiang River with developed economy are the major centralized growing areas of grain, cotton, oil crops, silk and tea. Guangdong, Guangxi, Fujian and some areas of Yunnan where are in the subtropics and tropics keeping a warm and wet climate all the year round have three crops a year and abound in sugar cane and rice. They are also the production base of rubber, coffee, sisalhemp, coconut, oil palm, and other tropical cash crops in China. Moreover, many kinds of subtropical and tropical fruits grow there as well, and oranges and tangerines, banana, pineapple, litchi, longan and shaddock etc. are well known at home and abroad. In the Southwest, because of the shortage of rainfall during the springtime, medium rice of one crop a year is planted in a large area. Corn, sweet potato and broad bean occupy quite a large proportion in the upland grain crops. This area is also one of the major growing area of tobacco, rape, tea, drug crops and other cash crops.