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How I Prepared my BIOCHAR to add to the Garden

Biochar, as it comes out of the fire is sterile, very dry and not fertile. It has a good ability to absorb cations (positive ions) which is what the elements that plants like such as nitrogen, phosphorus and potassium are. It also has the potential of soaking up moisture and improving the water retention of a soil. Although it is a micro-organism friendly material, it has not yet been colonized by the good guys. These micro-organisms have a complex interaction with plants. They help protect them against disease, help in the absorption of nutrients and generally improve the quality of crops.

So How do I process my Biochar?

I have 4 goals:

  1. Grind my biochar so the size makes it better as an additive. Some of the chunks were several inches across. I was hoping for a quarter inch texture.
  2. Add Moisture.
  3. Add Fertility.
  4. Inoculate the biochar with good micro-organisms.

When I moved I inherited an extra blender. This could be just the perfect tool for a small quantity.

bucket of biochar blender full of biochar bucket of biochar

I filled my biochar bucket with a water soluble fertilizer solution. It has macro and micro-nutrients. If I had good compost or manure I would have preferred this but since I have recently moved, my compost is young.

I used the blender to reduce the biochar to nice usable chunks. As I reduced the size of the pieces it gradually absorbed some of the water and fertilizer.

It was surprisingly clean and the bits I dropped on the deck just washed off with the hose. At the end I had a nice bucket of one eight to quarter inch or so pieces.

leaf compost before grinding leaf compost after grinding

So now I had my biochar in usable size chunks, was adding some fertility, and was gradually wetting the charcoal. I now needed to inoculate it with the proper micro-organisms.

I figured that a combination of compost and good soil would provide a good mix of soil microbes.

Although my compost was still a little rough it was doing really well. I hoped it had some good guys in there. I took a couple of fork fulls and roughly ground these in the blender using some of the extra fertilizer water. If was in fact very soft and I could have mixed it by hand and gotten the same result. The blender was faster though.

Since my garden had really grown well, I hoped that there was a good collection of soil micro-organisms and so I added a couple of shovel fulls of garden soil to my biochar mixture.

soil mixture

I let it sit for a couple of weeks and the water gradually was absorbed. The texture also changed to the texture of black earth.

After a month the mixture is very encouraging. It smells right and feels very nice. If I was a plant I would want to go sit in it. This is about a third charcoal, a third leaf compost, and a third garden soil.

It holds water very nicely but is not slimy or clay-like.

I am very happy with the look of the mixture and I will go and make a whole lot more. I don't think there is any real practical limit as to how much charcoal can be added. Figures range from 10 to 50 percent biochar. That's quite a suggested range.

Many people just add biochar to the soil after grinding it. It would take longer to reach its potential but that would work too. I'm just impatient.

I will be getting a chipper/shredder and I don't see any problem in using it to grind the charcoal. I guess I could mix it with leaves or compost if I have any trouble pushing it through. I don't think blenders are meant to grind biochar in large quantities.

Making charcoal/biochar. My experiments

email me: Christine

Small Print

This information is for general knowledge. This reflects my ideas and experiments. I try to get reliable information from first hand sources such as research papers but at this point there is not a lot of real research about the value of biochar as a carbon sink. There is lots on the value of biochar as an agricultural additive.