Scientific American, Nature - Using fertilizer wisely could help feed 9 billion people

Can the world's existing farmlands provide enough crops to satisfy the hunger of the nine billion people—up from seven billion currently—that demographers predict will be living on the planet by the mid-21st century? Or will more and more forests and other ecosystems have to be cleared to feed all the extra mouths?

A new study, published in Nature on August 30, suggests that increasing deforestation could be avoided provided farmers made better use of water and nutrients on land currently under cultivation around the globe.

The central premise of the new analysis is that intensifying agriculture where it already exists is the key to preserving a balance between farming and forests. To do that, the researchers from McGill University in Montreal and the University of Minnesota (U.M.) analyzed the so-called yield gap. That's the difference between what the highest yielding farm or area within a given region can produce—for example, corn—compared with what the average yield is. The difference between this best-practice farm and the average farm is the yield gap.