Millions of acres of North Dakota farmland are sown each year without the help of a single plow.

The practice of no-till or zero-till farming is gaining in popularity, with proponents saying it does everything from boost crop yields to help save the planet.

No-till farming involves using a machine to inject seeds and fertilizer into standing stubble from a previous crop, said Vern Hofman, an agricultural engineer with the North Dakota State University Extension Service.

Hofman said the seeding method is used on at least 10 percent of North Dakota's 20 million acres of farmland. More than half of the crops in the state are being planted using some sort of reduced tilling method, he said.

Minnedosa, Manitoba farmer Bob McNabb said that 25 years ago, "zero-tillage was a vague concept pursued by a fringe group of producers, academics, industry and government personnel."

Today, the practice is accepted worldwide, thanks largely to a group known as the Manitoba-North Dakota Zero Tillage Farmers Association, said McNabb, who has been no-tilling farming since 1978 and is a former association board member.

The zero-till group was formed 22 years ago in Minot. The association is planning its annual meeting this year in Bismarck on Feb. 4-5. Organizers say about 400 people from both sides of the border are expected to attend.

"The North Dakota-Manitoba collaboration was the forerunner of everything that has happened in zero-till farming, and it's been a catalyst in international activity," McNabb said.

He said advances in machinery, pesticides and seeds have made no-till farming take root all over the world.

Howard Dahl, of Fargo, helped develop no-till equipment in the late 1970s. His company, Concord Inc., began selling an air drill seeder in 1981. He sold the company to Case Corp. in 1996.

In the early 1980s, no-till farmers were looked at as "deviants," Dahl said. "It's mainstream now; there's nothing unusual about it anymore," he said.

Dahl said no-till farming requires only one pass over a field, which can cut fuel costs by 80 percent over conventional farming methods.

McNabb said large farm machinery manufacturers initially fought the concept of no-till farming.

"The large boys were against it because they looked at it as a threat to hours on the tractor," McNabb said. "They were afraid we wouldn't wear out tractors as fast, but they eventually had to go with what consumers wanted."

Keith Hovland, general manager of the John Deere Seeding Group factory in Valley City, said the facility was built in 1996 in response to the demand for air seeders.

Some 215 workers build seeding equipment at the Valley City factory, he said. Most of the machinery is sold within a 500-mile radius of the plant.

"The development of air seeders does cannibalize into other products," Hovland said.

But he said John Deere has seen increased sales of no-till equipment. "Our sales have been positive, as new technology is replacing old equipment," he said.

Hofman said the biggest benefit of no-till farming is that the land holds more moisture if it is not cultivated. It is especially effective in dry areas and in times of drought, he said.

Hovland said that's a big reason air seeders that plant without tilling are successful.

"It allows, frankly, more land to be farmed," he said. "It doesn't open the soil up so moisture can evaporate."

Manitoba farmer Kendall Heise said no-till farming also reduces potential environmental problems such as erosion.

Conventional farming releases carbon dioxide from the soil, contributing to global warming, Heise said. Carbon-rich soils also are more productive and help retain moisture, he said.

Many farmers knew long before researchers that no-till farming was good for land conservation, said Joe Breker, who farms about 2,000 acres near Havana, in southeast North Dakota, and has been no-till farming for more than 20 years.

He said he believes the farming practice will increase in popularity even more, though no one considers it a perfect planting method.

"It's not without its frustrations," Breker said. "It's still farming."