At Tin Dragon Cottages, last Saturday 29th April 2023, Christina Giudici demonstrated how easy it is to make biochar. She demonstrated the use of a low-tech low-cost method for making biochar in a pit kiln using prunings and fallen branches from around our property.
Because our Tin Dragon Team (Christine, Graham, James and Fraser-farm-dog) and five other local residents were keen to learn, we sponsored Christina Giudici for an instructional biochar field day.
What is Biochar?
If you are an avid gardener or simply love plants, you may have come across the term “biochar” at some point.
Christina explained that biochar is a type of charcoal produced by heating organic matter in a low-oxygen environment. The resulting highly porous charcoal is very stable and benificial for soil and plant heatlh.
Combating climate change
She also pointed out how making biochar is one of the ways we can combat climate change. The Intergovernmental Panel on Climate Change (IPCC) recognises biochar production as one of the key negative emissions technologies.
Converting waste plant material into a charcoal-like substance called biochar and burying it in soil can also be used to store carbon away from the atmosphere for decades to centuries.IPCC FAQ Chapter 4
By the end of summer we usually have a collection of fallen branches and timber off-cuts (flitches). Like many farmers, we would be completely burning-off these piles to ashes. But, this year we have decided to turn these piles of waste fuel into biochar. This is a win for the environment and a win for us, because we are removing fallen branches from our paddocks, sending fewer emissions into the air and making a stable carbon product to benefit our soil!
How to Make Biochar on the Farm
Of course there are many ways to make biochar from large to small scale and from high- to low-cost options. We chose to use a simple pit kiln, because this method suits our limited budget and is well suited to removing waste fuel on our property.
The flame cap method
Prepare the pit and the fuel
Graham and James dug a 1.5m cone-shaped hole in our river-flat paddock. Our good old Fiat tractor with grader blade made this an easy task! We already had a pile of tree branches courtesy of summer storms and wind. So with the aid of a chain saw, James cut the timber into suitable lengths for the pit. We stored the timber under a canvas ready for the field day.
Keep the flame cap going
We had perfect weather for being outside. While we were stoking the fire, we chatted about all-things biochar, soil and farming. Christina told some stories of her early experiments with making charcoal in pit kilns–some not so successful!
Stuart explained how he uses feedchar to improve the health and productivity of his commercial dairy herd. The lush rich paddocks of his farm certainly appear as a testiment to the value of this biochar treatment. Apparently freshly made clean charcoal is suitable for animals to eat. But, of course–for commercial uses–the biochar needs to be certified as safe for consumption – i.e. it must be free of all potential contaminants. So we will be using our home-made charcoal in the garden, only!
Smaller tree branches and twigs were thrown on top of the heavier flitches to keep the fire cap high. This helps make charcoal deeper in the pit.
Time to douse the fire
After about three hours, the fire was at a stage where we were ready to quench the flames with water. Besides, we were also wanting to stop for lunch. So, although we could have stoked the fire with more feedstock, the team took to the buckets!
Care was needed to pour the water down the sides of the pit till the pit was fully flooded. After the dust and steam had settled, it looked like we had made about 400 L of charcoal.
Over lunch we exchanged ideas about gardening, soil and the uses for biochar. We had such an enjoyable day, that we suggested we should do it again! Graham, James, Fraser (farm dog) and I would certainly be pleased to host another biochar bon-fire. Perhaps each participant could take away a bucket of biochar in exchange for sharing lunch and helping with the fire?
Then discussion moved to a more important topic – food! We agreed it could be fun for Christina to come back to show us how to make pasta. Apparently biochar can be added to pasta… How about it Christina?
It’s a Wrap – how to make biochar
- Size the hole or trench or cone to suit your feedstock
- Prepare your feedstock – sized for your pit and keep it dry
- Choose good weather – not windy
- Keep the flame cap high till all the feedstock is used, or the pit is full
- Locate the pit near a source of water for dousing
- Flood quench carefully
How to use biochar in the garden
While clean biochar may be good to feed to animals – including our chooks – it is not so good to add it directly into garden soils. This is because biochar is really good at soaking up nutrients from the soil. In fact, fresh biochar may compete with plant roots for the available nutrients in the soil and cause a reduction in plant growth.
So, to prepare the biochar we will be using the “car-crush” method to break up the biochar from our pit. We then intend using the crushed biochar in our chook house, by layering it on top of the straw bedding. The biochar will be useful in eliminating odour and soaking up the nutrients from the chook poo! Then we can rake it up and store it away for at least several weeks/months to let it compost. The aged compost should be good for our garden!
You can read more about how to use your biochar on Christina’s webpage. I will add to this page to show you how we prepare and use the biochar on our property, too!
learn more about the effects of biochar on soil properties in this DPI article.