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 agricultur al 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 second ary producer (livestock) was developed to assess food production poten tial and human carrying capacity of China's agro-ecosystem. It was est imated 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 fo r 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 yi eld. 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 le vel by 90%. Human carrying capacity of China's agro-ecosystem with the se levels of production was found to be 1,720 million, 51% more than t he current population.