introduction: making forest waste into a farming resource

My goal in 2014 was to design a biochar production system to match the existing scale of operations and power sources (solar and human power) at off-grid cannabis farming homesteads in southern Humboldt County, CA, in conjunction with manual fuel reduction in the surrounding forest.

This system is still in service today, just not for commercial cannabis anymore. It has four parts:

- trail building, for access to steep terrain

- a portable kiln, to make biochar where the brush is

- a hand-powered charcoal grinder

- a powered wheelbarrow, to neutralize the terrain

The kiln design is licensed by Vuthisa in South Africa. It is a flame cap type, consisting of a steel cylinder in three flanged sections joined by bolts, plus a lid. Snuffing the fire with the lid and sealing air leaks with mud makes water unnecessary for extinguishing it. Most of the forest is too far from water sources.

The grinder is my own design, based on an obsolete compost grinder (Rotocrop). The hopper holds a wooden cylinder with a 1/4" gap on either side, studded with decking screws and turned by hand. It fits on the lid of an ordinary 5-gallon bucket. It makes very little dust and converts all the char to a suitable size for biochar using the least work. More details and a CAD file here.

To move the kiln, char, and other materials in the steep terrain, I built carefully graded trails and retrofitted a wheelbarrow with a powered hub from China and a 24V battery that recharges from the house solar system.

Douglas-fir, a pyrophyte that displaces native oaks and meadows under fire suppression, is the principal substrate among many. Reclaiming oak woodlands and meadows is part of the purpose for this project. Fuel reduction costs are defrayed by utilizing the char locally as a soil amendment.

This low-tech system can be adapted to other places according to specific needs and constraints.