For many of us in affluent regions, our bathroom scales indicate that we get more than enough to eat, which may lead some to believe that it is easy, perhaps too easy, for farmers to grow our food. On the contrary, modern agriculture requires vast areas of land, along with regular infusions of water, energy and chemicals. Noting these resource demands, the 2005 United Nations–sponsored Millennium Ecosystem Assessment suggested that agriculture may be the “largest threat to biodiversity and ecosystem function of any single human activity.”
Today most of humanity’s food comes directly or indirectly (as animal feed) from cereal grains, legumes and oilseed crops. These staples are appealing to producers and consumers because they are easy to transport and store, relatively imperishable, and fairly high in protein and calories. As a result, such crops occupy about 80 percent of global agricultural land. But they are all annual plants, meaning that they must be grown anew from seeds every year, typically using resource-intensive cultivation methods. More troubling, the environmental degradation caused by agriculture will likely worsen as the hungry human population grows to eight billion or 10 billion in the coming decades.