The study found that improvements in technology, plant varieties and other advances enabled farmers to grow more without a big increase in greenhouse gas releases.

Much of the credit goes to eliminating the need to plow more land to plant additional crops.

Steven Davis, a geologist at the Carnegie Institution at Stanford, says the study addresses the question about whether organic agriculture could feed the world and whether traditional agriculture deserved the "black eye" it often gets from advocates of green farming.

The study found that without improved technologies it would have taken an additional 4.35 billion acres to feed the world.

The authors added the cultivation of that land, including the release of carbon in the soil and burning of brush and trees that covered it, would have released an additional 317 billion to 590 billion tons of greenhouse gases.

Leon Corzine, a past president of the US National Corn Growers Association and Illinois farmer, said it was something he'd been saying for quite some time.

He said new practices, new tools in the tool box, whether it's seed or equipment provided efficiency gains that are kind of dramatic.

But some environmentalists say the study is flawed arguing it's based on unrealistic scenarios of what would have happened if yields hadn't increased during the study period.