China's agro-ecosystem

China's agro-ecosystem is circumscribed by two critical environmental constraints; relative shortage of arable land and frequent regional lack or surplus of moisture. Intensive cropping and intricate water controls were developed over the centuries to deal with these constraints, and they remain the cornerstone of China's farming today. Human and animal labor continues to be an essential input, as are large quantities of organic fertilizers. Reliance on biomass fuels will also stay high for the foreseeable future. Farming modernization has brought the greatest advances to water control (both irrigation and drainage) and nitrogenous fertilizer production. However, widespread shortages and qualitative deficiences of modern inputs will not be easily eradicated. Total food output during the past three decades just kept pace with the population growth and the one-sided stress on grain production led to insufficient supply of edible oils, fruits and above all, animal foods. Overall use of external energy subsidies (direct and indirect use of fossil fuels and hydro-electricity) is still rather moderate but bold modernization plans for the 1980's would raise it substantially, thus lowering the currently high output/input ratio. Whatever the actual pace of modernization, careful attention to China's deteriorating environment will be critical. Land losses and soil degradation, erosion, deforestation and pollution are assuming alarming proportions and the long-range development of China's farming in balance with its protected environment is finally being recognized as the precondition of sustainable success.