Friday, 20 May 2016

Biochar farming idea

Here's an idea I hope gets stolen if it's good, and shot down early if it's bad. Also, I claim no expertise in biology, apiary science, or soil ecology, so this could be drastically off the mark.



1. Pyrolyze massive amounts of organic waste to make biochar.
2. Use the biochar to make a soil that mimics land after a forest fire.
3. Grow high-value crops that grow best after a forest fire.
4. Incorporate secondary processes like beehives.

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First, pyrolysis is a technique for burning lingen-rich plant matter (i.e. wood, bamboo, corn stalks) in a low oxygen environment. Pyrolysis can produce a stable, porous form of charcoal called biochar. Biochar is commonly applied to soil to improve its capacity to store water and nutrients. Soil with large amounts of biochar can approximate a very high quality topsoil call terra preta.

Also, the process of creating biochar is carbon-negative. The carbon in the biochar is effectively locked out of the atmosphere more permanently than it would be if the biological matter is left to rot. It certainly keeps carbon out of the atmosphere more effectively than simple burning.

What happens, however, when the soil is mostly biochar, with just enough other parts (or a layer on top) to keep it from blowing away? I suspect that you would have a soil similar to what would be found on the ground after a forest fire.

Pioneer species are the first organisms to thrive after a forest fire. These include valuable plants like morel mushrooms, and, particularly, fireweed. Specifically, I've heard that honey derived from fireweed is valuable. However, the cultivation of fireweed honey is difficult because it has to be done in areas of recent forest fires, and therefore can't be done in the same place for very long.

My idea is to make soil that mimics the ground after a recent fire, and maintain that state with frequent renewal of  biochar. Then, I want to use that soil to cultivate pioneer species.

With enough biochar, my hope is to have some farmland that can grow fireweed every year, and have permanently installed beehives amongst the fireweed. Rather than move the hives to where the land is suitable, I will work to maintain the land in a suitable state. With luck, the practice will pay for itself in harvests of fireweed honey, morels, and excess biochar.

If this works, then it can become a business that is both long-term profitable and carbon negative. There is an established demand for morels, and with more consumer awareness there could be a large demand for fireweed honey, so there is room for lots of people to try this.

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One potential issue is that bees prefer some flowers to others, and growing fireweed near the beehives doesn't guarantee that those are the flowers that will be used. Having a honey with a precursor that was part fireweed and part wildflowers may be acceptable, but it even guaranteeing that would mean influence an area much larger than the farmland.

Another issue is a sustainable supply of lingen-rich organic matter. Piles of slash and scrap wood are unreliable, one-time sources. Corn husks work nicely, but aren't available everywhere. Low-grade wood chips, called hog, would also work, but those are already used by pulp mills for energy. The city of Vancouver is already collecting organic waste for industrial composting, so it may be possible to tap into that pipeline. It will take some research to find how to use whatever is regularly available from local food processing and agriculture.


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ADDENDUM: user Osageandrot on Reddit, who does research on biochar for soil restoration, was kind enough to critique this idea and give some input. It was enough to show that this idea needs a major rework before anything more goes forward with this

First, any fresh biochar would need to be pre-aged by mixing with existing soil. This is because Polycyclic Aromatic Hydrocarbons (PAHs) are in too high of a concentration originally, and these will suppress microbal life.

Second, fresh application of biochar may not be necessary anyways. Most pioneer species are simply fast growers that need anything else that grows slower, but to a higher maximum, to be gone. Forest fires are not a necessary ingredient for a lot of these, but they just happen to provide the necessary conditions; clearcutting would do the same thing.

2 comments:

  1. How hard is it to do the pyrolysis on a large scale?

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    1. It's doable. There's even a mobile pyrolysis lab mounted on a truck. It has a 1 tonne per day capacity.

      http://www.canadianbiomassmagazine.ca/composites/alberta-invests-in-biochar-development-3162

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