Carbon coating gives biochar its garden-greening power

October 20, 2017
Carbon coating gives biochar its garden-greening power
Field experiment in Switzerland, with setup of compost windrows from mixed manure before adding the biochar. Credit: Nikolas Hagemann/University of Tübingen

For more than 100 years, biochar, a carbon-rich, charcoal-like substance made from oxygen-deprived plant or other organic matter, has both delighted and puzzled scientists. As a soil additive, biochar can store carbon and thus reduce greenhouse gas emissions, and it can slow-release nutrients to act as a non-toxic fertilizer.

But the precise chemistry by which biochar stores nutrients and promotes plant growth has remained a mystery, so its commercial potential has been severely limited.

Now, an international team of researchers, with key contributions by Colorado State University experts, has illuminated unprecedented detail and mechanistic understanding of biochar's seemingly miraculous properties. The Nature Communications study, led by Germany's University of Tuebingen and published Oct. 20, demonstrated how composting of biochar creates a very thin organic that significantly improves the biochar's fertilizing capabilities. A combination of advanced analytical techniques confirmed that the coating strengthens the biochar's interactions with water and its ability to store soil nitrates and other nutrients.

This improved understanding of biochar's properties could trigger more widespread commercialization of biochar fertilizers. Such a change could reduce global dependence on inorganic nitrogen fertilizers that have served as modern food-production workhorses for more than a century.

The international collaboration included CSU's Thomas Borch, professor in the Department of Soil and Crop Sciences with joint appointments in chemistry and civil and environmental engineering, and research scientist Robert Young. The CSU team contributed high-resolution performed at Florida State University's National High Magnetic Field Laboratory. Their data helped to confirm the composition of the biochar's nanoscale carbon coating.

The study analyzed the effects of a thin carbon coating on composted biochar. Credit: Mihaela Albu, Austrian Cooperative Research, Graz; Wolfgang Gerber/Nikolas Hagemann, University of Tübingen

"To characterize a super-thin carbon coating on a carbon substrate is nearly impossible," Borch said. "Our international team used many different advanced techniques to perform the analyses. Robert Young led our group's contribution of ultra-high resolution mass spectrometry to investigate the coating and probe its elemental makeup."

The study was led by Andreas Kappler, of the Center for Applied Geoscience at the University of Tuebingen, and geo-ecologist Nikola Hagemann. The authors set out to investigate biochar before and after composting with mixed manure. Using a combination of microscopic and spectroscopic analyses, the researchers found that dissolved organic substances played a key role in the composting of biochar and created the thin organic coating.

"This organic coating makes the difference between fresh and composted biochar," Kappler said. "The coating improves the biochar's properties of storing nutrients and forming further organic soil substances." Hagemann added that the coating also developed when untreated biochar was introduced into the soil - only much more slowly. Composting experiments were carried out on a small commercial scale using infrastructure and expertise of the Ithaka Institute in Switzerland.

Excessive use of mineral nitrogen fertilizers or liquid manure in agriculture has serious impacts on the environment. Such fertilizers cause the emission of nitrous oxide and result in nitrates leaching into the groundwater. As an eco-friendly alternative, scientists have suggested adding biochar as a carrier into the soil. But use of biochar on a large scale has not been economically viable because so little was known about exactly how it stores and releases nitrates.

"In agricultural crop production, higher yields usually only occur when biochar is applied together with nutrients from non-charred biomass such as liquid manure," Hagemann said. "Using without adding nutrients or with pure mineral nutrients has proved to be far less successful in many experiments."

Explore further: Biochar shows benefits as manure lagoon cover

More information: Nikolas Hagemann et al, Organic coating on biochar explains its nutrient retention and stimulation of soil fertility, Nature Communications (2017). DOI: 10.1038/s41467-017-01123-0

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Caliban
5 / 5 (1) Oct 20, 2017
So, notwithstanding that biochar is well understood to improve soils dramatically, with no negative impacts, it is only now this "improvement" promises increased profitability, that these guys can safely see their way clear to promote it as the positive good that it has always been known to be?

This stuff should have been massively produced and distributed as a cheap, environmentally benign and perpetual soil additive and "fertiilizer since day one --which-- incidentally, has only been for the past 10 years or so, since its discovery as a widely used soil additive in the Amazon basin.

Prior to that, even though similar treatments were known to be used all over the world throughout agricultural history, very little study had been made of it, as it was assumed to only provide a limited benefit in more or less slash-and-burn circumstances.
Whydening Gyre
5 / 5 (1) Oct 20, 2017
Unfortunately, it's a "coulda, woulda, shoulda - didn't..." kinda situation...
rrwillsj
not rated yet Oct 21, 2017
Sorry C, that your grandpa wasn't smart enough to figure this all out and leave you the fortune you are so entitled too. Pity of his failure to build a biochar monopoly.

Keep working on that time machine communicator of yours. You might yet get the opportunity to send a message back to gramps and wise him up!
Caliban
5 / 5 (1) Oct 21, 2017
Sorry C, that your grandpa wasn't smart enough to figure this all out and leave you the fortune you are so entitled too. Pity of his failure to build a biochar monopoly.

Keep working on that time machine communicator of yours. You might yet get the opportunity to send a message back to gramps and wise him up!


Sorry, swills, that your mama dropped you on your head several times too many.

I'll let you know when I perfect my time travelling contraption, so you can go back and be unborn.
rrwillsj
not rated yet Oct 22, 2017
Well, C, the key there would be to invent better condoms before '47. Cause my daddy always complained that the reason he fathered so many children, on so many women. Was that the damn things kept breaking on him. Quite the horny braggart,

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