I saw people talking about making use out of invasive plants and I have something to share here.
I recently used the "top lit open brush" method as showed in Skillcult's video to turn a pile of invasives into biochar. Here is the link, he talked about the pros and cons.
The pile was 6 ft tall, about equally wide at the bottom, mainly made of Japanese honeysuckles with some wild roses and thorny blackberries. I lit it up on the top and it only took less than 10 minutes to burn to the ground. Flaming shooting out of the center probably reached 15 ft tall with no visible smoke. I guess it was an indication that the volatile organic compounds were gassing off quickly and completly combusted.
When there was no more flame, I doused the pile with water to stop it from burning down to ash. I got 10 gallons of charred sticks this way with very little ash. now the chars are being soaked in compost tea before mixing into the compost pile.
I feel this method is particularly suited for burning large pile of small sticks and vines. Make the pile more vertical than cone shaped and burn it top down. That make a big difference of how much is converted to char rather than ash.
Thanks for reading and welcome to share your experience. Happy burning!
I wish my bamboo clumps will grow faster to provide lots of poles and young shoots.
Some invasives are useful: I enjoy the sweet aroma of Japanese honeysuckles blooms. The flowers are consider to be medicinal in TMC. Birds love the berries of bush honeysuckles and poison ivy, and rose hips. Lespedeza sericea is a legume and fix nitrogen. But they are taking the whole area over and choking the native plants.
So I need to take them under control but they are not suitable for composting. Right now for poison ivy, I just pull the vines and roots in late winter, when twigs are bare and the ground is loose. Then I cut them in segments to fit into the trash bag. Very time consuming but it works the best.
People say don't burn poison ivy because the urushiol will release in the air and cause breathers severe allergy reaction or even kill them. But looking at how a top lit brush pile is burning without smoke, I would suggest if urushiol, along with other VOCs, can be fully oxidized at the high temperature, then it is safe to burn. To do this, the poison ivy got to be dry and placed in the center of the pile. Just my hypothesis, I don't know how to find out if urushiol can still be intact and be released in the air. I am hypersensitive to poison ivy so don't want to find out by sniffing around. Any idea I can figure this out?
Making slow progress clearing the vines and planting trees. This time I tested the quality of char following the other post: https://permies.com/t/156900/BioChar-Lets I did two tests:
Washing hands with water only: yes, I can wash my hand clean without soap Water retention test: good retention of water of two times of the char weight
I didn't test seed germination rate though.
I usually soak the char in a big trash can of rainwater, throw in all kinds of "green" things for composting. Days later I built compost piles out of oak leaves and char mixture. The compost pile cooked within days and leaves decompose pretty quickly.