HU2506 | Summer 2008 | Science & The Public Sphere: The Example of Biochar | Terra Preta Nova

Agri/biochar in Australia

From the Australian Broadcasting Company science show Catalyst, an 11-minute video reporting on biochar, especially current research and agricultural applications: “Their early results promise green energy, soil restoration and greenhouse mitigation from an affordable technology that can remove more CO2 from the atmosphere than is released.”

abc australia

How Does Biochar Improve Crop Yields?

From the Sustainable Harvest International spring 2008 Newsletter, which includes a description of a biochar project workshop in Honduras:

Research so far has shown that biochar acts as a soil conditioner, not as a fertilizer. Indeed biochar improves the efficiency of fertilizers, be they chemical a or organic. It acts as a sponge to retain applied nutrients in the rooting zone, whereas these would be flushed with water deeper into the soil without biochar. Biochar also likely improves water retention in sandy soils and likely has beneficial
effects on the microbial communities in the soil.

Research has shown that when biochar was applied to soil, the emission of greenhouse gases such as nitrous oxide was reduced. This means that we can retain much-needed nitrogen in the soil for plant growth, while reducing the contributions of soils to global climate change. especially in tropical climates. So, by making biochar with biomass and applying it to soil, we can capture carbon and sequester it into the soil over extremely long time scales. Not only is carbon sequestered, but biochar added to soil progressively improves and has a better potential to increase crop yields.

More Context: “Sustainability”

All of our work in this course is in the context of sustainability and how the humanities, society, and technology can function in this domain — the spring section spent 14 weeks trying to define the concept — and our readings toward that end this summer include texts on faith and ecology, grassroots sustainability initiatives in Central America, poetry, and other explorations in imaginative, scientific, environmental, and technical communication. Today’s New York Times article on sustainability at Stony Brook University is therefore timely:

Sustainability is one of those fuzzy academic areas that varies in what it encompasses, even what it’s called. But on its philosophy there is consensus: it takes a multidimensional approach to understanding man’s interactions with the natural and man-made world, with a strong social-justice component (something environmental studies has traditionally lacked).

Across-the-curriculum sustainability was once the exclusive province of eco-colleges like Prescott in Arizona, which offers a Ph.D. in sustainability education, and the College of the Atlantic in Maine, where all students major in human ecology. But the subject has spread to mainstream colleges, as an end in itself (usually as a minor) or wrapped in another discipline (sustainability design, say, or economics).

The article appears in a “Green Revolution” special section of Education Life.

29 July 2008

We’ve read about how archeologists, ecologists, and soil scientists have studied areas around the Amazon river to try and understand the cultural and agricultural uses of biochar as long as 2,500 years ago.

An article in Discover magazine — “Black Gold of the Amazon” — discusses these contexts, and helpfully for our purposes, examples of the biomass makeup and a distinction between “smoldering” (the first step in carbon sequestration) and more traditional slash-and-burn agriculture:

The terra preta soils at Hatahara and the other sites are made from a mixture of plant refuse a and animal and fish bones, along with large quantities of charcoal that were deposited after settlers used stone axes and slow-burning fires to clear forest. Such smoldering fires produced more charcoal than ash. The charcoal, soot, and other carbon remains (collectively called biochar) retained nutrients, particularly potassium and phosphorus, that are limited in tropical soils. The resulting improvement in soil fertility may have allowed the land to support a larger, more stable crop-based population, although studies of fossilized pollen have not yet revealed the specific plants they cultivated.

In addition, soil scientist Johannes Lehmann is quoted in the article as arguing that in integrating biochar in agriculture, “you wouldn’t just be carbon neutral, you would be carbon negative, drawing carbon dioxide out of the atmosphere, producing energy and improving the climate in the process.”

Biochar and CO2

24 July 2008
Posted by Michael

One of our ongoing questions is how can creating biochar be considered a carbon-negative process if we’re clearly releasing CO2 when firing our mass in the initial burning process? Jeanne Roberts, in this post on Biochar: A Good Way to Store CO2,” summarizes that process, at least when it comes to burning wood, “as in a forest fire, only part of the CO2 is released, and the rest remains contained in the resulting charcoal…”

She states later in the article that,

Biochar is a carbon-negative addition to soils that reduces total fertilizer requirements, reduces runoff, reduces nitrous oxide emissions from crops by up to 80 percent, and enhances crop yields. The gases produced during pyrolysis can be used as fuel to create more biochar, making the process even more carbon negative.

Other scientific articles support this carbon-negative aspect, but we still need to learn about the effects when burning or smoldering compost, for example, or what some studies refer to as “agricultural waste.”

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