In a post about carbon and farming a couple of days ago, a reader noted that I wasn’t talking about biochar, which surprised me, because I’d never heard of it! That’s one of the great things about farming – there’s always something new to learn. So I did a little bit of research and thought I’d share what I learned with everyone else. Here’s the low-down.

Biochar is a clever idea that has the potential to divert enormous amounts of carbon from the atmosphere and sequester it into the soil. Basically, whenever trees or crop residues burn or rot, they release most of the carbon they contain into the atmosphere. This is a natural process, although one that can be accelerated or initiated by the actions of man. However, this CO2 can be stored in the form of biochar. (Biomass-derived charcoal = “biochar”.)

To produce biochar, you take biomass, any biomass, and subject it to a variety of processes. People have made biochar for thousands of years; pre-Columbian Central and South American farmers used to produce it as a soil supplement to increase their crop yields. It’s also known as dark earth or terra preta. You can make biochar as simply as taking a pile of biomass, setting it on fire, and covering it with soil so that the fire smolders and pyrolysis takes place. (Pyrolysis is heating in the absence of oxygen.) The resulting substance is a very high carbon charcoal-like material that makes a fantastic soil additive. The beautiful part is, once the biochar is mixed into soil, it remains stable for hundreds or even thousands of years. There are huge biochar deposits in parts of South America that go down as deep as two meters – soil that was made by primitive farmers thousands of years ago is still there, still holding on to that carbon.  (continue reading below graphic)

Today biochar is produced with much more advanced techniques, and the most recent development is a proprietary process created by an Australian energy company, BEST Energies. Their “Agrichar” process uses a low-heat pyrolysis that actually produces energy and synthetic gas as by-products. You can buy Agrichar, and other biochar products, or make biochar for yourself. It’s a great soil additive and has literally doubled total yields on test fields. Biochar reduces nutrient leaching, increases bioavailability of soil nutrients, improves water retention, and cuts down on the need for fertilizer. Probably the best part is that creating biochar doesn’t have to be high-tech; it’s a tool that can be used by the poorest and least sophisticated farmers, as well as huge high-tech corporate farms.

Biochar won’t solve the global warming problem on its own, but it does seem like it could be a major tool in getting control of the carbon budget. I will keep up to date on developments with biochar, and will keep you posted.

Additional Reading on this Topic: Discover Magazine Biochar