Actual and potential yield for rainfed and irrigated maize in China

A crop yield model (YIELD), that uses climatic and environmental data to calculate yield and water consumption for a variety of major crops was applied specifically to maize (grain corn) in the region of China and Korea, by examining the parameters of potential and actual yield. A network of 241 stations provided the seasonal climatic input, which consisted of data averaged over approximately a 20 year period. Among the simulated results, highest yields under full irrigation (first growing season) occurred in the Yangtze River area, northward to Korea, Kweichou and Szechwan Provinces, and northcentral China, whereas least yield was found for the western interior. High yields exceeded 12,000 kg/ha per harvest. Under rainfed conditions, only the Yangtze River region retained its predominance. In order to achieve optimum crop yields, about 800 mm of irrigation water was needed in northcentral China, contrasted with none required in the south and east of China. Making certain dietary assumptions, the calculated grain corn production could potentially support between 700 and 400 million people, depending on the irrigation strategies adopted. If corn were used as feed stock for beef, only between 100 and 60 million persons could be supported. A sensitivity analysis was applied to determine the degree of error introduced by faulty, uncertain, or missing environmental input data for the stations utilized in this study.