Biochar can be made using simple materials found on the farm. The goal is to burn plant material with very little oxygen so it turns into charcoal, not ash.
Materials needed
Dry plant materials like maize stalks, rice husks, groundnut shells, dry grass, or small wood pieces
A pit in the ground or a metal drum
Matches or fire source
Water or soil for covering
Step 1: Prepare the materials
Collect dry biomass. Cut large pieces into smaller sizes so they burn evenly. Make sure the material is dry for good results.
Step 2: Dig a pit or use a drum
Pit method: Dig a shallow pit about 1 meter wide and 0.5 meter deep
Drum method: Use a metal drum with small holes at the bottom for limited air flow
Step 3: Start the fire
Light a small fire at the bottom using dry leaves or grass. Let it burn until you have a steady flame.
Step 4: Add biomass slowly
Add the plant material little by little. Do not dump everything at once. This helps control oxygen and prevents full burning into ash.
Step 5: Control oxygen
This is the most important step. When the material starts turning black (char), reduce air by:
Covering partly with soil, or
Closing the drum
The aim is to allow heating without too much air. This is what makes biochar instead of ash.
Step 6: Stop the burning
When most of the material has turned black, stop the fire by covering with soil or sprinkling a small amount of water. Do not let it turn into white ash.
Step 7: Cool down
Leave the biochar to cool completely. Do not expose hot char to air, as it may continue burning.
Step 8: Crush the biochar
Break the biochar into small pieces or powder. This makes it easier to mix with soil.
Step 9: Mix before use
Before applying, mix biochar with manure, compost, or animal waste. Let it stay for a few days. This helps it absorb nutrients and become more effective.
Application in the field
Apply about 2 to 5 tons per hectare for normal soils
Up to 10 tons per hectare for poor soils
Mix well into the topsoil before planting
Important tips
Do not use wet materials
Do not allow full burning into ash
Always mix with organic matter before use
In summary, making biochar is simple and low cost. With proper control of fire and oxygen, farmers can produce a useful soil amendment that improves crop growth.