FORBES, Australia — Across 40,000 hectares of Australia’s vast agricultural heartland, an unusual approach to slowing the wrecking ball of climate change is taking hold.
Farmers are trying to harness the superpowers of the tiny underground tentacles of mushrooms to extract carbon dioxide from the air and store it underground.
It is part of a big bet that businessmen and investors around the world are making on whether the earth can clean up climate pollution.
They are using a variety of technologies on farmland not only to grow food, but to consume the excess carbon dioxide produced by more than a century of burning fossil fuels and intensive agriculture.
Why mushrooms?
PhotoStuart McDonald, a fifth-generation farmer near Canowindra, looked for newly planted seeds coated with Loam’s fungal treatment. atthew Abbott for The New York Times.
Because fungi act as nature’s carbon traders.
While planting their crops, farmers add a pulverized powder of fungal spores.
The fungus attaches to the roots of crops, takes the carbon that is absorbed by plants from the air and stores it in underground storage in a form that can keep it underground for much longer than the natural carbon cycle.
The Australian company Loam Biowhich produces mushrooms, is one of many startups that have mobilized hundreds of millions of dollars in investments to use soil to remove carbon dioxide from the atmosphere.
Like Loam Bio, companies like Andes and Groundworks Bio Ag are also experimenting with microbes.
A researcher inspects mushroom samples at one of Loam’s laboratories in Orange, New South Wales. Photograph by Matthew Abbott for The New York Times.
Lithos and Mati offer farmers crushed volcanic rocks that absorb carbon to spread it on their fields.
Silicate Carbon is grinding concrete waste into a fine powder, while several companies are burning crop waste into charcoal.
The appeal of the Australian startup is that it doesn’t ask too much of farmers.
Air-dried soil samples from farms are being prepared for carbon analysis at Loam’s lab. Photograph by Matthew Abbott for The New York Times.
“Pretty simple,” is how a fifth-generation Australian farmer named Stuart McDonald described his experience sowing a fungal spore layer with his wheat and canola seeds on his farm near Canowindra this year.
“It doesn’t ask us to change too much. It’s not a huge capital investment.”
Start-up
Most of these initiatives are still in their early stages, and it is not yet known exactly how much excess carbon they can remove or how long they can keep it underground.
But its collateral benefits can be equally profound.
Steve Nicholson and his grandson, Hamish Nicholson, in a newly planted field on the family farm. Photograph by Matthew Abbott for The New York Times.
All of them aim to restore the soil health that have been degraded by decades of intensive agriculture, restoring the microbes and minerals they once contained.
The potential for carbon removal from soils is enormous.
Soils contain three times more carbon than the atmosphere and can potentially absorb more than 5 gigatons of carbon dioxide carbon per year, or one-seventh of all the carbon dioxide that human activity injects into the atmosphere, according to the Intergovernmental Panel on Climate Change.
That makes them the second largest deposit of carbon in the world, after the oceans.
“I think soils will play a key role,” said Rob Jackson, a climate scientist at Stanford University, though he was skeptical about whether the promise of fungal additives in field trials could have a statistically significant effect on working farms.
“We would need to touch billions of acres to make a real difference,” he said.
Foto Matthew Abbott para The New York Times.
Solutions
Not to mention that agriculture itself creates a climate problem, accounting for a quarter of the world’s greenhouse gas emissions.
Loam Bio’s fungal talc has been spread on 40,000 hectares in Australia this year, with 100,000 expected to be in operation next year. Half a dozen farmers in the United States are testing the product on their soybean fields.
Field trials are underway in Canada and Brazil.
Loam Bio has attracted $100 million in investment so far, making it one of the best-funded of the many startups looking for ways to store more carbon in the ground.
Reservations
Critics worry that new technologies treat the symptom rather than the cause of climate change.
“They cannot be used as an excuse to continue burning fossil fuels,” Jackson said.
Tegan Nock, co-founder of Loam Bio and a sixth-generation farmer, agrees.
“This is just one of the things that can buy us time,” he said.
Why Australia?
Not all farmers do it out of altruism.
More carbon means better soil health and higher yields. But in Australia, farmers have another motive.
They hope to harvest a credit harvest issued by the government if they can prove they have stored carbon underground.
A controlled burn on a farm near Parkes. Farmers in the area have been using burning for generations, believing it helps rejuvenate the soil by killing weed seeds and pathogenic fungi. Photograph by Matthew Abbott for The New York Times.
This is not the first time that farmers in the area have tried to take advantage of soil carbon.
McDonald, 52, once trucked in solid waste from Sydney’s sewage system to fertilise his fields and measured a small increase in soil carbon.
But he has no idea how long it lasted.
Some farmers planted trees on part of their land and soil carbon increased for a few years, then leveled off.
Critics said carbon credits were awarded not for substantial changes but for seasonal fluctuations in the climate: in unusually wet years, carbon would build up in the soil, then dissipate in dry years.
A study warned that the amount of carbon credits issued for agricultural projects was inflated.
Accounting for soil carbon is complicated by the fact that it comes in different forms.
Most soil carbon is in the form of highly volatile organic matter.
On agricultural land, this is plant residues or manure.
It can re-enter the atmosphere in a matter of years, or a drought or fire can burn it up even faster, releasing carbon dioxide back into the air.
But there are more stable types of soil carbon, including one that attaches to minerals in the soil and remains there for a century or more.
Loam Bio says its fungal spores can help generate that more stable soil carbon.
They measure it for their farmer clients, using soil cores one metre deep.
Fungi do vital work underground.
They take the carbon dioxide that plants extract from the air during photosynthesis, store it underground, and return the nutrients that plants need.
For Alan Richardson, a soil biologist at the Commonwealth Scientific and Industrial Research Organisation, a government agency in Australia, the concept of using fungi to store carbon underground makes sense.
But this would only work if farmers applied the fungi year after year, allowing the soil to generate carbon for many years.
“The fundamental principle behind it is sound, but we don’t know whether it will translate into practice,” he said.
Bet
Still, Steve Nicholson, a farmer in Forbes, is so optimistic about the outlook that he signed a 25-year contract with Loam. “It’s a gamble,” he said.
“But it’s a very, very good bet.”
Loam technicians measured their reference soil carbon in February, at the peak of the hot, dry season.
They will return next February to find out if their soil carbon has increased and to determine how much of it is in the most stable forms.
Loam Bio’s Nock tells his clients they can expect to store one to two tons of stable carbon in every hectare, or 2.4 acres.
The Australian government’s carbon credit agency will have to verify how much carbon Nicholson has added before issuing credits.
Nicholson hopes to collect his payments next July.
His profits will depend on Australia’s carbon price at the time. He’s looking at more than 100 Australian dollars, or about $65, per hectare.
The devastated soil of the world
Agriculture is increasingly affected by its own environmental costs.
The quest to feed the world has devastated the earth, while emitting huge amounts of greenhouse gases.
Cutting down forests. Plowing the land. Applying chemical fertilizers. This activity has altered much of the Earth.
The changes are evident on McDonald’s farm.
His ancestors, settlers from England, began farming in Australia in 1888.
They grew hectares of wheat, foreign to this continent.
They raised cattle and sheep, also foreigners.
Over the decades, Australia became a agricultural power.
Also over the decades, as agriculture intensified, topsoil layers were eroded, soil carbon levels dropped, and the land became degraded.
“Erosion was something that everyone accepted,” McDonald said.
Until they couldn’t take it anymore.
About 20 years ago, McDonald, like many of his neighbors, stopped farming.
After each harvest, he let the crop stubble decompose naturally.
This helped retain moisture in the soil and curb erosion, but did little to generate carbon in the soil, according to scientific studies.
Now, climate change poses a new risk.
And drier and warmer future threatens to release much more carbon from the soil, according to scientific models.
Australia’s climate goals mean agriculture must change.
His government has set itself the goal of reducing its greenhouse gas emissions by 43% by 2030, compared with 1990 levels.
Agriculture accounts for around 14% of these emissions.
Neil Westcott, also a wheat and canola farmer and mayor of a small farming town called Parkes, has his sights set on that future. He wants to reduce the climate impacts of his farm. He believes he will soon have to do so, if the government demands cuts in climate pollution or if overseas customers want low-carbon crops.
Westcott, 64, has stopped raising sheep, which produce methane, a potent greenhouse gas, and has planted about a quarter of his 6,000 acres with the mushroom dust.
He expects carbon credits to be available, but has no plans to sell them yet.
He wants to save them for when he has to offset carbon emissions from his own farm.
“I have my own carbon footprint that I need to cover,” he said.
“I’m sick of talking about it. I have to do something.”
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