传统有机农业结合可养活全世界

In rural Maryland, an hour-and-a-half drive from Washington, Bill Mason is tilling his fields to plant organic maize and soybeans.

About two-thirds of his 340 hectares are organic, but not all of them. And that bothers some people.

“There are some die-hard organics," Mason says. "They think every organic farmer should not be planting any conventional.”

As both an organic and conventional farmer, Mason sits right in the middle of a long-running debate over how best to feed the world.

Organic vs. conventional

Demand for organic food - produced without artificial fertilizers or pesticides - is growing worldwide, but some experts doubt a growing world population can be fed if farmers don't use these chemicals.

An April study in Nature found organic farming is 25 percent less productive on average than conventional farming. But while some say we cannot feed the world with organic agriculture, others say we cannot feed the world without it.

Critics of conventional farming say excessive fertilizer use pollutes waterways, kills fish and contributes to climate change. Customers will pay a premium for food produced without pesticides and fertilizers.

But Mason says his organic crops typically do not produce as much. “We are finding that our corn yields are about three-quarters of the yield of a normal conventional crop.

Ecological consequences

With those lower yields, feeding the world organically could require clearing more land for farms.

“We’ll have to get more land into cultivation to do it that way," says Columbia University soil scientist Pedro Sanchez, "with horrible, negative ecological consequences.”

Experts say deforestation to make way for agriculture is already contributing to climate change and a loss of biodiversity.

And farmers will have nine billion mouths to feed by mid-century, which puts agriculture in a difficult position.

“Right now, we can’t feed 9 billion people with the ways we’re farming, whether it’s conventional or organic,” says U.S. Department of Agriculture researcher Michel Cavigelli.

Working both sides

So experts are working on both sides of the equation. Cavigelli is working to improve the productivity of organic farms using natural fertilizers like chicken manure. The trouble, he says, is that often it does not provide enough nutrients.

“We need to improve all systems. And so, what’s the best way to do that, both to feed the world’s population but also to do it in the way where we’re not destroying the planet?”

Many of the African farmers Pedro Sanchez has worked with have used synthetic fertilizers to triple their yields, making a huge difference in their food security.

Blended solution

“But as a scientist, I don’t like that as the solution," Sanchez says. "And I will not preach it as the solution. I want to integrate that with organically-produced nutrients.”

Organic nutrients, such as fertilizing cover crops, have worked out for Bill Mason and his conventional-farming neighbors are taking notice.

“I think there’s ideas that we’re using that are carrying over to the conventional world,” Mason says.

So the ideal solution to feeding a world of nine billion might not necessarily be a choice between organic or conventional farming, but rather a blend of both.