Crop yields to feed a growing global population a concern

Crop yields to feed a growing global population may have reached a maximum in some parts of the world, researchers at the University of Nebraska-Lincoln report. Writing in the journal Nature Communications, the researchers say about 30 percent of the major global cereal crops -- rice, wheat and corn -- may have reached their maximum possible yields in farmers' fields, raising concerns about efforts to ramp up food production to meet increasing world populations. While estimates of future global food production have been based largely on projections of historical trends, those trends were driven largely by rapid adoption of new technologies that allowed for an increase in crop production, they said. But since many of those technologies were one-time innovations, the projections of future yields may be overly optimistic, Kenneth Cassman and Patricio Grassini of the UNL agronomy and horticulture department and Kent Eskridge of the statistics department said. Analysis of past yield trends in countries with greatest cereal production provide evidence against a projected scenario of ongoing linear crop yield increase, they said. The findings suggest the rate of yield gain has recently decreased or stopped for one or more of the major cereals in many of the most intensively cropped areas of the world, including eastern Asia, Europe and the United States, the researchers said. This decrease or stagnation in yield gain affects 33 percent of major rice-producing countries and 27 percent of major wheat-producing countries, they reported.