POTENTIAL PRODUCTIVITY AND HUMAN CARRYING-CAPACITY OF AN AGROECOSYSTEM - AN ANALYSIS OF FOOD-PRODUCTION POTENTIAL OF CHINA

Widespread concern has emerged about the ability of China's agricultural systems to feed its future population. An ecosystem approach based on adaptation of crops to physical environment and energy/mass balance between the physical environment, primary producer (crops) and secondary producer (livestock) was developed to assess food production potential and human carrying capacity of China's agro-ecosystem. It was estimated that average potential primary productivity (total net biomass) of China was 27.4 t ha-1 yr-1 for arable lands and 4.9 t ha-1 yr-1 for grassland; they could thus produce 4.5 x 10(9) t dry matter yearly. Average potential yield of cereal crops (grain) was 6.9 t ha-1, total output of cereals could reach 9.7 x 10(8) t, 2.42 times the present yield. Livestock systems could produce 1.5 x 10(15) kJ of edible energy and 9.5 x 10(9) t edible energy for humans, higher than the current level by 90%. Human carrying capacity of China's agro-ecosystem with these levels of production was found to be 1,720 million, 51% more than the current population.