The Next Big Thing #4: Nine Billion Served
Posted by Richard Conniff on December 27, 2013
The great challenge in agriculture is to double the amount of food being produced without plowing under what’s left of the natural world. The twentieth-century Green Revolution did it with massive doses of commercially manufactured fertilizer. Now we need to ramp up food production again—but without the environmental costs. Conventional fertilizer-manufacturing processes release large amounts of carbon dioxide from fossil-fuel combustion. Even worse, only a fraction of the nitrogen fertilizer actually gets into the crop. The rest ends up in ocean dead zones such as the one at the mouth of the Mississippi River—or in the atmosphere in the form of nitrous oxide, a far more potent greenhouse gas than carbon dioxide.
But researchers have recently discovered an unexpected diversity of soil microbes capable of breaking down nitrous oxide into nitrogen. They’re also figuring out how farmers can use these bugs at precise temperatures or moisture levels, or at certain stages in the life cycle of a plant, in order to get more nitrogen fertilizer into crops—and less into the environment. “Precision agriculture” is the term for that kind of farming, and microbes will play a major role in making it happen.
For instance, one reason it’s so hard to feed families in the tropics is that the clay soils there trap phosphate. A farmer may need to dump 100 units of imported fertilizer onto the land just to get 10 units into his crops. A lot of farmers go without costly chemicals, or they clear more forest to grow the food needed. But researchers at the University of Lausanne and the National University of Colombia are now working with a mass-produced root fungus that efficiently delivers phosphate to cassava, a staple food for much of the developing world. In the first season of field testing, this fungus cut phosphate use in half while boosting yields by 20 percent.
Microbes in the roots of plants are also nature’s way of getting nitrogen into plants, thus enabling peanuts, soybeans, and other legumes to extract (or “fix”) it out of thin air at a rate of hundreds of pounds of nitrogen per acre. Researchers have developed nitrogen-fixing bacterial strains that can increase yields for some crops by 50 percent. The hitch is that hardly anyone invests in getting those improved strains to farmers in the developing world, says Ken Giller of N2Africa. Given access to nitrogen-fixing bacterial strains that already exist, he says, subsistence farmers would have far less need to cut down forests to make new fields.