Only about 3.4% of the land area, comprising 160,000 hectares (395,000 acres), was used for seasonal and permanent crop production in 1998. In 2002, agriculture contributed about 45% to GDP, and engaged 93% of the economically active population. Nonetheless, Bhutan's near self-sufficiency in food permitted quantities of some crops to be exported to India, in exchange for cereals. Since there is little level space available for cultivation, fields are generally terraced. Stone aqueducts carry irrigation water. The low-lying areas raise a surplus of rice; in 1999, output of paddy rice was estimated at 50,000 tons. Other crops include wheat, maize, millet, buckwheat, barley, potatoes, sugarcane, cardamom, walnuts, and oranges. Part of the crop yield is used in making beer and chong, a potent liquor distilled from rice, barley, and millet. Paper is made from the daphne plant, which grows wildly. Walnuts, citrus fruits, apples, and apricots are grown in government orchards.
Agricultural holdings are restricted to 12 hectares (30 acres) per family; almost all farm families own their own land. Since the mid-1960s, the government has established demonstration farms, distributed fruit plants, and implemented irrigation schemes. High-yielding varieties of rice, wheat, and corn seeds have been introduced. Under the 1987–92 economic plan, farming cooperatives were introduced and apiculture was promoted.