Thanks to Yale e360:
Researchers are finding that when pulverized rock is applied to agricultural fields, the soil pulls far more carbon from the air and crop yields increase. More studies are underway, but some scientists say this method shows significant benefits for farmers and the climate.
On a hot and humid August day near Geneva, New York, Garrett Boudinot stands in a field of hemp, the green stalks towering a foot or more over his 6-foot, 4-inch frame. Today, the mustached Cornell University research assistant will harvest six acres of the crop, weigh it in red plastic garbage bins, and continue to analyze the hundreds of water samples taken with measuring devices called lysimeters that have been buried in the field over the last three months.
Boudinot, part of a research team at Cornell University, will sweat through the next two days of field work to see whether an unusual component added to the soil earlier in the year helped increase yields and sequester carbon. This soil amendment “we just call lovingly ‘rock dust,’ which isn’t very descriptive,” says Boudinot. “But it’s really silicate rocks that have been pulverized to a fine powder.”
The hemp field trial is just one of the projects being led by Ben Houlton, dean of Cornell’s College of Agriculture and Life Sciences. For the last two years, he and colleagues at the Working Lands Innovation Center, a research consortium based at the University of California, Davis, have been testing various soil amendments that grab carbon from the air and trap it below ground. They’ve tested biochar, manure, and rock dust used on the New York land and California farm plots, and so far, the most effective soil treatment is basalt pulverized into dust.
“As far as I can tell,” says Houlton, “ours is the largest-scale project of its kind, using this intensive sort of scientific approach.”
The hemp field experiments go beyond testing which amendments increase yields and sequester carbon and examine how much rock dust should be applied for best results. Some sections got 20 tons of rock dust per acre, while others got 40, allowing the researchers to get a more fine-tuned picture of the relationship between the dust, the soil, and the crops. The research adds to a growing body of scientific work showing the potential for these soil amendments to become one of the many measures needed to help solve our climate crisis.
Agriculture accounts for nearly a quarter of the world’s carbon dioxide emissions, making the farming sector an important part of efforts to reach net zero by 2050 and limit global warming to 1.5 degrees Celsius, an increase scientists warn the world should not surpass if we want to avert some of the more drastic consequences of climate change. To help reduce carbon in the atmosphere, scientists once proposed seeding the oceans with iron. That tactic was criticized as environmentally damaging and ineffective and has not gained widespread acceptance. But seeding soils with carbon-capturing rock dust could.
In addition to Houlton, scientists from the United Kingdom to Canada are testing various soil amendments on agricultural lands, assessing how much carbon they sequester through a process called enhanced weathering. While Houlton’s researchers apply basalt to hemp in New York and to alfalfa and olive trees in California, scientists working with the University of Sheffield’s Leverhulme Centre for Climate Change Mitigation in the U.K. are spreading basalt on cornfields in Illinois and on sugarcane in Australia. In Ontario, Canada, researchers are applying wollastonite from a nearby mine on soybean and alfalfa fields…
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