Land use change in rice, wheat and maize production in China (1961–1998)

Abstract

Land use change in China is related closely to global environmental change and global food security. In this paper, we analyzed land use change for rice, wheat and maize production in China during 1961–1998 based on long-term historical data. The results indicated that the total land area planted for cereals had both increased and decreased between 1961 and 1998. The total area in cereals increased or remained unchanged during 1961–1978, a period when the “Cultural Revolution” occurred, and also increased during 1986–1990 when the Chinese government increased subsides to agriculture. However, the total area in cereals declined during 1980–1985, a period corresponding to the implementation of the “household responsibility system” policy, and during 1991–1995, when a large proportion of the rural labor force moved to urban areas. The center of cereal production has moved towards northern China although the major area planted for rice, wheat and maize together is still located in southern China. The yield per hectare for all crops has increased from 1.21 t/ha in 1961 to 4.83 t/ha in 1998, but the yield per unit chemical fertilizer use decreased from 164 (rice), 44 (wheat) and 93 (maize) kg/kg in 1961 to 10 (rice), 6 (wheat) and 9 (maize) kg/kg in 1998. The increases in yield per hectare and production per capita appear mostly due to the increased industrial energy inputs, especially the rapid increase in chemical fertilizer use after the “household responsibility system” in late 1970s. The decline of the yield per unit chemical fertilizer use appears as a result of fertilizer saturation, soil degradation, soil and water pollution, the shortage of irrigation in the north, the threat of flooding in the south, and poor and low quality land use, as well as other social, economic and technical issues. With limited reclaimed land resources remaining and a near saturation in the response of crops to fertilizers, increasing food demand from the increasing population will have to come mainly from increased land productivity that will almost certainly continue to lead to the decline of energy (e.g. fertilizer) use efficiency and continued environmental degradation. Alternatively China may begin to import large amounts of food. This situation will generate adverse effects on sustainable development in China, as well as food security in the world, especially if world energy is in short supply.