Glacier flour fertilizes a garden of ideas
The potential of ‘glacial flour’ for agriculture is re-emerging, according to a study by the IC3 polar research centre in Tromsø, which notes that there are limits to its use, as some of this flour could be toxic in certain cases.
A little more potassium to grow legumes? Apply trace element-rich “glacial flour” to your soil, and your crop’s growth will improve… Not so fast, this new idea is still being tested.
Sarah Tingey, a biogeochemist from the IC3 polar research hub at the University of Tromsø, and her colleagues at the University of Bristol confirm, in a study published in iScience (Cell editions) on January 17, that “glacial flour” improves legume cultivation. However, they note that it may contain metals such as arsenic, which are toxic for human consumption.
Rock mill
By flowing much more slowly than rivers, glaciers rub the bedrock and grind pebbles. The grains are gradually refined, like flour in a mill.
This fresh, fine sediment is reactive and moves downstream in meltwater. The “flour” stagnates in natural reservoirs, such as lakes, or on the coast, in estuaries and fjords.
“Studies show that when a glacier retreats due to climate change, it is capable of exporting more glacial flour – at least initially. After a while, if the glaciers disappear entirely, then the production of glacial flour fades. Although large quantities of material are produced, it is not an inexhaustible source of crushed rock,” explains Sarah Tingey to Polar Journal AG.
“We’re revisiting some of these old strategies”
Before the Green Revolution, in 1894, a scientist by the name of Julius Hensel used crushed stone to regenerate soil fertility.
“They’re supposed to improve soils and absorb atmospheric CO2,” says the researcher. “That’s why we’re revisiting some of these old strategies.”
Recently, Jemma Wadham and Jon Hawkings from the University of Bristol discovered a rich array of nutrients and trace elements in Greenland’s “glacial flour” that are beneficial to agriculture.
The use of Greenland ice flour in agriculture has also gained ground. In 2023, researcher Minik Rosing was awarded a 100,000 euro grant and the Frederik Paulsen Prize from the Polar Circle Assembly.
“Glacial flour” could open up new economic opportunities in Greenland.
“I hope our project will help redefine the Arctic as a region of choice for finding solutions to global problems, and as a region inhabited by peoples who have power and impact,” the scientist had said.
For their part, Sarah Tingey and her team decided to investigate other geological sources, collecting samples of glacial sediments in the Himalayas and Iceland.
Camping at an altitude of over 3,000 metres in northern India, she stayed close to a glacier front between the end of the monsoon season and the onset of winter storms. In Iceland, she ventured on foot along the glacial tongues of the Sólheimajökull.
The Icelandic rock flour harvested is dark and basaltic, while the Himalayan is orange and yellow, shiny and sparkling. “We wanted to see how geology influences the nature of these alluviums and plant growth,” she explained.
So Sarah Tingey grew soybeans in the laboratory. Both rocks improved plant growth and health. Glacier dust contains phosphorus, iron, potassium, silicon and other elements. Icelandic basalt achieved better results.
The dose exceeded health standards
The legumes used in the experiment exploit symbiotic bacteria to capture atmospheric nitrogen from their roots. “Glacial flour” can also provide micronutrients for these microbial communities.
The only problem measured, much to the team’s surprise, was that the Himalayan sediments contained enough arsenic to contaminate the plants. After the experiment, the seedlings accumulated the toxic element.
“Just because there’s arsenic in this area doesn’t mean there’s arsenic in all Himalayan glacial flours,” says the researcher. “With Icelandic flour, arsenic levels remained below the toxic limit, even at the highest doses. My next experiment will look at a much wider range of trace substances.”
Both experiments show better growth, but the overall results raise new questions.
Which geological soils can be used? What type of soil can be amended in this way? The study involved laboratory experiments, but does it also work in the field?
“If glacial flour is added to an already very similar soil, as may be the case in Greenland, it may not be as effective,” she notes. “On the other hand, on an acidic tropical soil, there may be a better effect?”
This would require the transportation of “glacial flour”. As such, its carbon footprint should be included in the discussion, given that one of the objectives is the sequestration of CO2 in the soil.
“We studied glacial flour from Chhota Shigri, in the Indian Himalayas, not least because there are farming communities growing food not far from the site,” recalls Sarah Tingey.
The extraction of glacial flour adds to question of sustainability of the process.
“I think that glacial flour should be extracted where it is already a problem rather than in preserved natural areas,” the researcher believes. ”It accumulates behind dams, for example, or near a port area that needs to be dredged.”
A multitude of news ideas that provide plenty of grist for the mill.
Camille Lin, Polar Journal AG
