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Go Black to Go Green

By: Tyler Nicoll

Staring at a pile of black charcoal, it’s hard to imagine how it could be a key tool used to solve pressing environmental issues. But that’s exactly what it has been repurposed to do. The soil amendment, biochar, can reduce fertilizer needs and improve our water quality while simultaneously offsetting carbon emissions. Although biochar may not single handedly create a carbon neutral society or eliminate pollution, it is certainly a step in the right direction, and part of the integrated approach that can curb the momentum of our negative impact on the planet.

The topic of reducing carbon emissions is continuously in the spotlight as a part of global discussions focused on creating sustainable societies.

Naturally occuring soil (left) vs. Terra Preta (right)
Image courtesy of International Biochar Initiative.

As with the development of all new technologies, it is beneficial to reflect on historical practices. At the end of the 19th century, explorers in the Amazon Basin discovered dark, fertile soils uncharacteristic of the region, that they later determined were man-made, and on top of that at least hundreds of years old! They named the soil, “Terra Preta” meaning “dark earth.” Farmers improved the soil by adding charcoal, which is still present in the soil supporting more productive vegetation to this day.

Biochar, currently on the forefront of sustainable research, is the modern form of Terra Preta. One innovative aspect of biochar is the utilization of current biomass waste. For example, crop residues, wood scraps, land clearings, animal manure; virtually any organic material can be input into a pyrolysis furnace to produce biochar. The pyrolysis furnace heats the biomass in the absence of oxygen, converting it into a stable carbon form (charcoal) and captures the gases and oils that are given off as by-products. These by-products can be used as a fuel source. If the organic biomass was not converted into biochar, it would decompose naturally giving off greenhouse gases into the environment.  Instead, the process of producing biochar creates an energy source and a soil amendment all from material that is considered waste!

Biochar cycle.
Image courtesy of Dr. Lehmann, Cornell University

So why do we need biochar in the soil? Biochar forms a carbon sink in the soil that has been shown to remain stable for more than a thousand years. The process of making biochar and adding it to soil prevents carbon dioxide from ever entering the atmosphere. In addition, biochar does more than simply sequester carbon – it improves soil properties to reduce the harmful effects of agriculture and storm water runoff on water quality. Biochar has a porous structure which prevents fertilizer and water from leaching through the soil and into the groundwater. This makes fertilizer and water use more efficient, decreasing the total amount of water and fertilizer that needs to be used and that can ultimately end up in our water sources. The porous surface has a high cation exchange capacity and also makes a great home for beneficial soil microbes – both of which are vital to the nutrient cycling plants require.

The biochar company re:char, works with local farmers in Africa without access to enough water and fertilizer. The farmers use small biochar furnaces as well as their own resources to produce biochar, successfully increasing crop yields. This is just one success story of many.

Creating biochar is not only for large-scale farming. Pyrolysis furnaces can be engineered for specific industrial applications or as simple do-it yourself models like the ones used in Africa. Biochar has a multitude of different applications from agriculture, backyards gardens, restoration sites, to urban street plantings where the biochar acts as a filter for storm water.  So if you want to go green, go black – use some biochar in your own garden!

Me in front of 10 tons of biochar for use in restoration tree planting.
Photo credit: Tyler Nicoll.

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