Redefining Agricultural Yields: From Tonnes to People Nourished per Hectare
Just 55 percent of all of the calories grown on croplands directly end up in the food system. The remaining calories are used for animal feed (36 percent) and biofuels (9 percent).
And as you can see from the map above, a lot of farmland in the United States is not used to grow food, it is used to grow animal feed and biofuels. Over two-thirds of the calories grown in the U.S. are fed to livestock. And for every eight calories of corn and soybean fed to livestock, only one of those calories ends up on our plates.
If we ate all of the crops we grew, on average, croplands could feed 10 people per hectare. But because only 60 percent of what we grow ends up as food, farms only feed 6 people per hectare (see below). Because we use so much of what we grow for animal feed and biofuels, farms in the U.S. feed less people per hectare than those in China and India.
I published this research with my colleagues at the University of Minnesota in Environmental Research Letters. See below for a video version of the abstract.
