Using a top-lit updraft “conservation burn” to transform old forest residue (pine slash) into biochar in the wildland-urban interface – Pictorial

Dr. Richard Freeman

The biochar process demonstrated with these photos yielded about 6 cubic feet of good quality char.

The wood came from an old forest slash pile near a residential site in the wildland-urban interface in NE Washington state. It was partially decomposed, and because it was highly flammable, it posed a wildfire risk to the residence. Thus, it provided a great opportunity to make some biochar.

I started by sorting the wood into two or three piles based on average diameter of the stick. (No picture). Then I laid out a few parallel sticks of the largest diameter wood as base rails. The wood in the picture ranges from 2-4″ diameter (average).

On top of these rails and perpendicular to them I laid sticks from the small diameter pile. The pile was thus up to 2 feet in height.

On top of this pile and parallel to the smallest wood I laid the largest wood. The pile was thus up to 3-1/2 feet in height.

On top of this pile I laid some some small diameter wood for kindling out of the pile in the background of the above photo.

Next I gathered my tools — buckets not shown here.

Using the weed torch, I ignited the pile from the top.

When the flame had almost subsided, I added some fine fuels from the remaining pile in the background. This addition extends the heat treatment of the remaining wood and yields some extra char fines.

When the last flame subsided, I doused the pile with water

Then I stirred it up with a pitchfork and doused it again. I repeated these steps until all white from the ash was gone and every particle was coated with water.

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