Cook Biochar With Dinner to Improve Soil

As my regular readers know, I'm moving toward using human-powered tools wherever possible. But that left me with a problem: How do I dispose of sticks, tree trimmings and palm fronds? I don't want to throw that wonderful organic matter away. I don't want to buy, borrow or use a gas-powered shredder to make mulch, if I can avoid it. And I certainly don't want to labor all day with saw and hatchet making wood chips. (I'm just too darned lazy!) So I think I'll make biochar for the garden.

That's what the pre-Columbian Amazonian civilizations did to make "terra preta," a premium, enriched soil still highly prized in Brazil for orchards and potting soil. (Though to be fair, biochar was only part of the formula along with feces, compost, bones, potsherds and other additives.)

Biochar Soil Benefits

According to International Biochar Initiative, adding biochar to soil creates:

• Reduced leaching of nitrogen into groundwater
• Possible reduced emissions of nitrous oxide
• Increased cation-exchange capacity resulting in improved soil fertility
• Moderating of soil acidity
• Increased water retention
• Increased number of beneficial soil microbes

For these reasons and the fact that biochar sequesters carbon dioxide, biochar is all the rage in organic farming research, though there are dissenting opinions.

I think one of the risks of jumping on the biochar bandwagon is that, in typical uber-industrialist fashion, researchers and entrepreneurs are looking at large-scale production and usage, and biochar is already on the market as a soil amendment.

This seems crazy to me. Does it really make sense to reduce Global Warming by burning lots of biomass? Even if true – even if the chemistry works out – it's anti-intuitive and part of the same old crazy thinking that got us into this mess.

But then, I'm not talking about building a biochar factory. I'm just talking about good garden management and improving my soil with what's at hand – and spending as little money and effort as possible.

Cooking Biochar – and Dinner!

Biochar is a fairly simple to make: It's basically the not-totally-burned wood left over from a campfire. You start by burning organic matter – wood, dried grass and weeds, corn husks, dried manure, paper, whatever – then before it gets going too good, you smother the fire, cutting down the oxygen. In traditional charcoal making, they get a big bonfire started, then cover it all with an inch or so of dirt. In the low oxygen environment , some chemicals get burned off and some get carbonized. Scientists call this process incomplete pyrolysis.

Estufa Finca in action. Photo by Art Donnelly of SeaChar.

Now, I could do this in a pit in the yard (though with the risk of code violation). Then I could either scoop out the biochar for use or just bury it. But that seems a waste. All that heat should be used for something ...

How about cooking dinner? SeaChar, a nonprofit that's "mission is to develop, promote and share positive tools for carbon negative living," has invented a biochar producing cookstove, the "Estufa Finca." It's cheaply made with a 5-gallon metal paint bucket, half a 1-gallon tomato can and some corrugated metal roofing.

By cleverly controlling airflow, it creates an oxygen-poor environment to produce biochar while efficiently burning volatile gasses to increase heat and reduce soot. Typical cooking times are 30% less than on an open fire.

So once in a while, I can cook dinner with tree trimmings, palm fronds and dead weeds. In my little yard, it won't be an everyday thing, but maybe I can grill every couple weeks or so. Then when the biochar cools, I'll smash it down to crumbles with a hammer and sprinkle it on my compost pile or somewhere else in the yard.

Over time, adding biochar to my land will enrich the soil, which is the foundation of a good garden.

#biochar #estufafinca #soilimprovement