That's where Lynch's idea for improving roots comes in. He calls the concept "steep, cheap, and deep" – developing crop roots that grow steeper and deeper into the soil, making them able to find more moisture and nutrients, thereby reducing need for irrigation and nitrogen fertilizers. (With crops that rely on phosphorus, he's breeding shallow roots, since phosphorus is typically found in topsoil.)
Working with bean breeders around the world, for example, Lynch's team has identified root traits that can produce "two or three times more food without fertilizer," he says, using conventional breeding techniques that select for superior root traits.
His work on new varieties of corn is less advanced. But Lynch has published a paper that identified a previously unrecognized trait that improved yields eight times in experimental corn lines grown under drought conditions.
A key component in raising American corn yields in recent decades, nitrogen fertilizer, is more expensive in Africa than in the United States, Lynch says. In addition, as it runs off fields it can contaminate water supplies and produce nitrous oxide, a potent greenhouse gas.
While Lynch employs traditional cross-breeding methods, genetically modified (GM) crops seem likely to play an important role in the second Green Revolution. Concerns about safety and unexpected consequences have led to a slow rate of adoption in Europe and parts of Africa, although GM crops are already widely planted and consumed in the US.