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

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 nine billion people with the ways we're farming, whether it's conventional or organic," says US 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. He says 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 many experts say feeding a world of nine billion will not be a choice between organic or conventional farming, but rather a blend of both.

Related stories:

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Why 'precision agriculture' is a good investment

The limits to organic farming in feeding the world

Organic food, a way out

（来源：VOA 编辑：旭燕）