This story was updated with the National Organic Standards Board's vote.

A crucial battle in a long-brewing conflict over organic farming came to a head Wednesday when an influential government panel met to discuss whether soil is an essential element of organic farming.

On one side: "Dirt first" traditionalists who say that fruits and vegetables must, by definition, be grown in soil to qualify as organic.

On the other: Agri-technophiles who say "controlled environment" methods like hydroponics and aeroponics are just as deserving, dirt or no dirt.

The panel late Wednesday vote in favor of some of these novel farming techniques, disappointing organic pioneers but stoking the hopes of tech-focused agriculture startups.

The debate over who deserves the U.S. Department of Agriculture's lucrative organic label came amid broader challenges over the best way to feed a growing population on a warming, resource-challenged planet where most of the arable land is already used for agriculture.

Both sides made forceful arguments that organic farming, with its focus on using natural substances and eschewing synthetics, has an increasingly important role to play in protecting the climate. Though vegetables grown in soil may look and taste like those grown in controlled environments—with their roots bathed in liquid solutions or stacked in towers—they may have very different carbon footprints.

"You're farming in a smaller space and with less resources and reduced shipping and refrigeration," said Marianne Cufone, executive director of the Recirculating Farms Coalition, which represents hydroponic and aquaponic farmers. "It seems to me it's one of the best ways to improve our situation when it comes to climate change and agriculture. To consolidate and grow up is smart."

But for traditional organic farmers, shifting resources and research dollars to soil-less forms of agriculture ignores the carbon-storing potential of soil-based agriculture and the energy footprint of growing crops indoors.

"By changing the way we farm the soil, we can improve the sequestration potential of the soil," said Jeff Moyer, executive director of the Rodale Institute, which has long advocated organic farming methods. "We know, globally, as we look at climate change solutions, the soil plays a huge role. Going indoors is not the solution."

Since the launch of the National Organic Program in 2000, the Agriculture Department has allowed hydroponics and other forms of soil-less or container-based agriculture under the organic label. But in recent years, organic farmers had pushed the National Organic Standards Board (NOSB)—the body that decides what practices are permitted under the organic label—to make an official decision on whether these agri-tech approaches count as organic.

The board voted to allow hydroponics and aquaponics, and it will discuss what additional labels organic-certified hydroponic and aquaponic products will carry. It voted to exclude aeroponics, in which the roots are bare but sprayed with liquid nutrients.

"By siding with current science and recognizing that existing law purposely leaves the door open for various farming methods, the NOSB is sending a critical message that sustainability and innovation are valuable in U.S. agriculture," Cufone said.

Investment Pours in for Novel Techniques

The debate, which has festered for years, has become increasingly bitter over the last 12 months as more investment and interest has centered on these novel farming techniques, including a $200 million investment in the San Francisco-based start-up Plenty by tech-investment firm SoftBank Vision Fund. Plenty plans to build indoor vertical farms, where produce is grown in stacks under artificial light, outside 500 cities around the world, using technologies including remote sensing to gage growing conditions and artificial intelligence experts to translate data from the plants.

"We've seen a lot of new money coming into this," said Katelyn McCullock, an economist with the American Farm Bureau Federation, American agriculture's largest trade group. "There's a lot of interest in this area and not from the sources we're used to seeing it from."

According to AgFunder, a start-up funder that also tracks investments in agriculture, investors have committed $285 million so far this year—including the Plenty investment—dwarfing investment last year, which saw $70 million, and 2015, which saw $53 million.

Meanwhile, sales of organics are booming, reaching a record $47 billion in the U.S. last year, and demand for organics is outstripping supply.

"Organic is obviously super popular, but there's gaining traction in other clean methods of farming," said Louisa-Burwood Taylor, a spokesperson for AgFunder. "When these companies can price their produce cheaper than organic and offer pesticide-free and clean, then I think you've got an interesting dynamic and competition to organic."

Who's More Climate-Friendly?

Traditional, soil-based organic farmers say that the competition shouldn't be allowed in the first place, noting that soil-less agriculture isn't permitted under the organic label in other countries, including Mexico, one of the U.S.'s biggest agricultural trading partners.

At rallies across the county, pro-soil advocates have demonstrated, with farmers holding homemade signs reading "Don't Water Down Organics with Hydroponics" and "Real Farmers Do it in the Dirt."

"There will be no sign warning the customers that this fauxganic food was grown without soil," the Keep the Soil in Organics coalition said in an appeal to supporters on its website. "And so we are in a final battle for the soul of the organic label."

Critics of controlled agriculture systems point out that, in order to simulate the sun, indoor farms consume huge amounts of electricity, negating possible climate benefits.

Even supporters acknowledge the high electricity demand is a downside. "It is an issue," conceded Sally Rockey, executive director of the Foundation for Food and Agriculture Research, which recently gave a $2 million grant to New Jersey-based AeroFarms, the country's largest vertical farm operator. "When you use electricity the way you have to in controlled environments, you want to take a look at what that means as far as your carbon footprint."

But, Rockey said, there are some appealing trade-offs. "Oftentimes we don't use pesticides because plants aren't exposed to air," she said, "and generally we use a lot less water."

Controlled environment farms can also be constructed near cities, potentially cutting down on emissions connected to transportation.

The pro-soil growers say, however, that the climate benefits, to the extent that there are any currently, are being overplayed by tech interests with deep pockets.

"We can mitigate emissions. We know that," said Moyer, who is a former head of the standards board. "They're using the story of climate change, but that's not the reason for their existence."

The other side, meanwhile, accuses the pro-soil camp of slinging mud to protect their lucrative market.

"If you have a method of growing that reduces stress on resources—like water, like space, like energy—that can produce healthy, good-quality food, maybe in more abundance and with more efficiency, why wouldn't you support that?" Cufone said. "The only reason I can think of is money."

What Does the Research Say?

So far, studies suggest that indoor agriculture consumes more energy than traditional soil-based farms. Researchers at Cornell University have examined the carbon footprint of an indoor hydroponics farm, operated in New York state, and compared its energy use to an outdoor farm in California. Factoring in the energy used to transport the produce from California to the East Coast, they found that the hydroponics operation used twice the energy.

"At least from an energy or carbon footprint standpoint, growing these produce items in our northerly climate, where we use a lot of light and fossil fuel for heating, you use twice the energy inputs versus field-grown. But that was the status quo technology for 2008," said Neil Mattson of Cornell's School of Integrative Plant Science. "We feel there's the ability to improve that by producers adopting more energy-efficient lighting and using renewable energy systems."

Beyond Cornell's research, studies comparing the climate benefits of traditional farming systems and controlled environments remain pretty thin. But the climate impacts of various farming methods are a growing conversation within the organics industry, and more research is underway.

"We're starting to get concerned that an assumption's being made that if you're not growing in the outer crust of the earth, there's no way you can sequester carbon or mitigate climate change," said Nate Lewis, a farm policy director for the Organic Trade Association, the organic industry's largest trade group. "Those are assumptions. I haven't seen anyone compare the full life cycle of a tomato grown in one [system] versus the other. There are so many factors."