Biochar is a wonderful soil amendment. It is made from organic material burned in the absence of oxygen via pyrolysis. Once burned, the char is processed in a method called activation which hydrates the char and gives the mineral retention and microbial life a kick start.
Biochar is an excellent addition to raised beds and to grow mixes.
Here are a few of the benefits:
- Water retention (in the char pores)
- Microbial life density (they live in the pores)
- Mineral retention (trapped in the pores)
- Nitrogen trapping
- A long term source of soil carbon
All of these are useful in our loamy sand. This is in addition to biochar’s role in sequestration of carbon for the long term.
Norm Baker, a scientist and grower in northwestern Washington state, did a trial growing Yukon Gold potatoes in the same soil with three different amendment schemes: 1) native soil, 2) native soil amended according to OrganiCalc, and 3) native soil amended according to OrganiCalc with the addition of biochar. The results are impressive, with the biochar plot outproducing the other two dramatically.
We have added up to 10% activated biochar to our garden soil. The first experiment was done by adding 10% unactivated biochar to part of one bed. The biochar had been soaked in water but no other nutrients or compost had been added. In 2-3 years that was the best part of the garden. Then we got enough biochar to amend the rest of the garden. We activated it by soaking it in water with a soup of nitrogen nutrients and microbes, then we put it in an active compost pile, then on the garden. The results have been really positive. Once we fenced the deer out, the garden has been producing amazing veggies!
There is no end to trimming and pruning woody materials on our one acre ranch. We are always in the mood for appropriate technology, especially when it is elegant and inexpensive. So when we heard about the Kon Tiki biochar kiln and how it makes inexpensive, copious biochar efficiently and with minimal smoke our ears perked up.
Many biochar retorts we have seen are complicated affairs requiring external energy to heat the biomass stock material to the temperatures needed for pyrolysis. Not so the Kon Tiki. It’s secret is in the shape. The inverted cone contains the fire in such a way that the biomass stock is not burnt up but the gases are, all without producing excess smoke. It uses no external heat source.
We have a smaller version that is designed for backyard biochar production – the CharCone. Unfortunately the CharCone is out of production, but if you or someone you know is a welder, you might be able to construct something similar.
But there is no need to buy anything in order to make biochar. It is possible to dig a pit the right shape and make biochar in it. See this presentation.