Detailed analyses of wheat yields around the world show a disconcerting stagnation or collapse in many locations since the heyday of the Green Revolution. (Courtesy: Deepak Ray, Institute on the Environment)
The Green Revolution has stagnated for key food crops in many regions of the world, according to a new study. Led by IonE research fellow Deepak Ray, the study team developed geographically detailed maps of annual crop harvested areas and yields of maize (corn), rice, wheat and soybeans from 1961 to 2008. It found that although virtually all regions showed a yield increase sometime during that period, in 24 to 39 percent of the harvested areas (depending on the crop) yield plateaued or outright declined in recent years. Among the top crop-producing nations, vast areas of two of the most populous - China and India - are witnessing especially concerning stagnation or decline in yield. "This study clearly delineates areas where yields for important food crops are stagnating, declining, or never improved, as well areas where yields are still rapidly improving," Ray says. "As a result, it both sounds the alert for where we must shift our course if we are to feed a growing population in the decades to come, and points to positive examples to emulate." Interestingly, the researchers found that yields of wheat and rice - two crops that are largely used as food crops, and which supply roughly half of the world's dietary calories - are declining across a higher percentage of cropland than those of corn and soybean, which are used largely to produce meat or biofuels.
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