You can either dig a pit that’s roughly rectangular in shape, or you can dig a cone-shaped pit, which will ensure a more controlled burn. [1] X Research source If digging a pit to put your biomass in, the hole should be big enough to fit whatever materials you’re burning. [2] X Research source If digging a cone-shaped pit, the size of the pit should be around 20 in (0. 5 m) in diameter and about 40 in (1 m) deep, getting narrower the deeper it goes. For reference, you will need about 4. 4 lb (2 kg) of biomass to produce 1. 1 lb (0. 5 kg) of biochar. [3] X Research source Make sure that there is no ban in place where you live regarding burning materials. [4] X Research source
Before lighting your biomass, take the proper safety precautions to protect both yourself and the surrounding area. [6] X Research source Wear protective gear, and have a hose on hand ready to extinguish the fire at a moment’s notice. Wetting the ground around your pile or trench can also prevent the fire from spreading and getting out of control. Do not leave the fire unattended and keep children away.
Once you start to see embers or white ash start to form, start layering more biomass on top. You can estimate the rate at which you should be adding more biomass by the amount of smoke being produced compared to the amount of ash forming. A lot of smoke billowing up means that you’re adding too much too fast. If you’re seeing a lot of ash forming, then you’re not adding biomass quickly enough. Place the new biomass as evenly as possible over the fire and cover any gaps. This will help keep oxygen at a low level and make sure your biomass burns into charcoal, not just ash.
The smoke coming from the burning biomass will be white at first. This is mostly just water vapor, so nothing to worry about. The smoke will then turn yellow as the resins in your wood begin to burn, and it will finally turn into the thin, bluish-gray smoke that you’re waiting for. Instead of piling soil on top, you can also quench the fire by dousing it in water. [10] X Research source
The biochar will look like blackened pieces of wood or whatever you decided to burn and will likely be under a pile of ash for you to dig up. Collect the biochar in a bucket or wheelbarrow using a shovel, since it may still be a bit hot, and let it cool before storing it or putting it to use.
For reference, you will need about 4. 4 lb (2 kg) of biomass to produce 1. 1 lb (0. 5 kg) of biochar.
Keep an eye on how much ash and smoke is forming as you burn your biomass. If too much ash is piling up, that means you need to add more burning material. If you’re seeing too much smoke, hold off on adding more biomass for a little bit. Do not leave the fire unattended at any point and keep children away.
Biochar dust can be irritating to your eyes, skin, and respiratory system. Avoiding dumping biochar into a container or onto the soil from a high up. Also, avoid moving biochar around when it’s windy.
An essential part of using biochar is “charging” it, or loading it with key nutrients that will help the soil. Not charging your biochar can cause it to actually soak up the nutrients from the soil and reduce the soil’s effectiveness. Charge your biochar by mixing it with fertilizer, usually compost, and letting it sit for about 10 days. You can use a 50:50 ratio of biochar to compost, but most farmers use 20% biochar and 80% compost.
Storing biochar in a bag prevents dust from becoming airborne in the container, which can become fuel if exposed to an ignition source. Never store biochar near food or beverages.
