Food security in China underlies the foundation of the livelihood and welfare for over one-fifth of the world's population. Soil degradation has an immense negative impacton the productive capacity of soils. We simulated the effect of soil degradation, which occurs in combination with increases in population size, urbanization rate, cropping intensity and decrease in cropland area, on long-term food security in China using a web-based land evaluation system. Our results predict that food crops may experience a 9% loss in productivity by 2030 if the soil continues to be degraded at the current rate (business-as-usual scenario, BAU). Productivity losses will increase to the unbearable level of 30% by 2050 should the soil be degraded at twice the present rate (double-degradation scenario, 2 x SD). China's capacity for producing food from agricultural crops will be either adversely affected by the loss of cropland area (130, 113 and 107 million ha in 2005, 2030 and 2050, respectively) or favorably affected by agricultural intensification (in terms of the multi-cropping index at 120,133 and 147% in 2005, 2030 and 2050, respectively). The loss of cropland is predicted to cause a 13-18% decrease in China's food production capacity by 20302050 relative to its 2005 level of 482 Mt, while agricultural intensification is predicted to cause an 11-23% increase. In total, China will be able to achieve a production level of 424 and 412 Mt by 2030 and 2050, respectively, under BAU, while this production will be only 386 and 339 Mt under 2x SD, respectively. In per capita terms, the relationship between food supply and demand will turn from an 18% surplus in 2005 to 3-5%, 14-18% and 22-32% deficits by 2030-2050 under the zero-degradation (Ox SD), BAU and 2x SD scenarios, respectively. Our results show that the present-day production capacity will not sustain the long-term needs of a growing population under the current management level. Technical countermeasures and policy interventions need to be enacted today in order to avoid food insecurity tomorrow. (C) 2009 Elsevier Ltd. All rights reserved.
