As the world's population balloons to 9 billion by 2050, based on current agricultural practices, the global food system may not be able to meet the demands of an increasingly affluent and urban population.
Yet shifting crops away from animal feed and biofuels to growing food exclusively for human consumption could increase global calorie availability by as much as 70 percent, according to a study from researchers at the University of Minnesota, St. Paul.
The researchers mapped global patterns of crop production and allocation of maize, wheat and rice in China, Brazil, India and the United States to calculate the amount of human-consumable calories. Combined, the countries represent nearly half of total cropland area and global calorie production.
"Looking at alternate diet scenarios, if we shift all crops from current uses to direct human consumption, we could feed an additional 4 billion people," said the study's lead author, Emily Cassidy, a researcher at the University of Minnesota's Global Landscapes Initiative.
The Food and Agriculture Organization of the United Nations estimates that demand for meat and dairy will increase by 68 percent for meat and 57 percent for dairy by 2030.
Animal products, which require more calories to produce than they end up creating, also need more land and represent one of the largest sources of greenhouse gas emissions.
Vast differences in consumption
The researchers created a livestock conversion formula to calculate the efficiency of plant and meat production based on calorie and protein content. On a global scale, 36 percent of calories from crops are used for animal feed, while 12 percent of those feed calories contribute to the food supply in the form of meat and animal products.
Mapping crop production in the countries had data limitations, from feed production to biofuel. The researchers could not disentangle genetically modified foods from those produced without bioengineering methods.
"A limitation of this study is that it treats plant and animal proteins equally, even though their proteins differ in bio-availability and amino acid content," notes the study.
The researchers suggest that managing crops exclusively for human consumption rather than for animal feed and biofuels may help ensure global food security.
Agricultural practices and economic conditions vastly differ among the four countries where the fractions and flow of calorie delivery were observed.
In India, the researchers examined how 89 percent of produced crop calories were directed to food, 6 percent to animal feed and 5 percent to other uses during the study period. In comparison, the United States used 27 percent of crop calorie production for food, with more than half of crop production by mass going to animal feed.
China, the world's top producer of rice, used 82 percent of the crop's calories for direct human consumption. The country is also the world's biggest producer of maize as a feed crop with 77 percent of produced calories in maize directed to animal feed.
Small shifts in crop allocation may be needed
Like the United States, Brazil uses the majority of produced plant protein for animal feed with 79 percent of crop calories, mainly from soybean production, used for animal feed.
Food production "is not limited by land, but by demand," said Bruce Babcock, director of the Biobased Industry Center and a professor of economics at Iowa State University.
If farmers moved acreage out of maize production and only supplied food for human consumption, there would be an increase in supply, and "if we move into a vegan diet, there would be millions of acres that would be idle," he added.