What Does Adding Biochar (Charcoal) do to your garden?

The question appeared in my mind “What does charcoal actually do in gardening?”. So, I started digging and I am now going to be adding biochar to most of my garden beds in the future. The benefits are great and anyone with a few trees can create there own.

The Benefits To Be Had

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Adding charcoal or “biochar” to your garden has a great deal of benefits. By providing a very porous and sturdy surface larger pieces of biochar provide a great aeration aspect. One of the benefits that I consider “major” is the water and nutrient retention. Through the same porous surface this is made possible.

Helps with runoff

As you water your garden the excess nutrients that didn’t get absorbed by any plants will get pushed into the ground water. One way to help prevent this runoff is by adding biochar to your garden. The water and nutrients become absorbed into the charcoal and is released into the soil at a later point.

Great aeration

By creating pockets of loose soil the charcoal creates a lighter and better aerated soil. It can also be used in the bottom of flower pots as a lighter replacement for gravel.

Awesome soil additive

With a high potassium content biochar is an alternative for the lime that gets added to your garden beds. It also happens to increase the pH level, making it a great additive for your roses. When planting orchids it can be used to substitute some of the wood normally needed.

Creating Your Own Biochar

Materials

• A hole in the ground (around 8 – 12 inches deep / however wide you like)
  • Keep in mind you will be moving this dirt back so don’t go too big
• Dried Yard waste
  • Tree Branches
  • Leaves
  • Garden waste such as corn stalks
• A way to light it on fire
  • Magnifying Glass and Sunlight
  • Lighter

• A shovel
  • Not required but easier than doing it with your hands

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Steps

Circle Hole: Easy method, less biochar, more smoke, and greater pollutants

1. Place your materials to be burned into your hole.
2. Light it on fire
   • This is where you will need to watch the fire as it will happen kind of quickly
   • First the smoke will be white (water vapor)
   • Then it will turn a yellowish color (starches and sugars)
   • Finally it will turn grey (carbon)
3. Once the smoke turns grey you will want to cover it with soil leaving a small hole for oxygen control
4. After the fire has smoldered for long enough, most of the wood will be covered in white ash with black undercoat.
   • This takes some skill and judgment to achieve the correct amount of time
5. Next you will cover the fire with water putting it out and stopping the burning process.
6. Once the fire has been extinguished you can uncover it and voila you have lumps of biochar.
7. Breaking up the biochar at this point adds the porous effect mentioned earlier.
8. The final step in this process is you will need to charge the biochar

Cone Hole: More Biochar and less pollutants

As described by Allotment-garden.com in an article named “How to make Biochar at home“

• Start by digging a cone shaped pit. The size is variable, but I’d suggest no bigger than a metre in diameter at the top or it will get too hot and need too much wood to keep fed. 60 cm is a reasonable size for a first burn.
• Get a pile of wood together, cut into convenient lengths around 30 cm is best. Keep this back from the pit as you don’t want it catching fire prematurely! Brash wood is ideal for making biochar.

• Start by building a small fire in the base of the cone, using dry twigs. Once this is going well begin adding some more twigs and then larger pieces of wood. Let these burn until they start turn white.

• Then add another layer of wood. Once again wait until this turns black and starts to develop a layer of white ash. Keep repeating until you reach the top of the cone or run out of wood.

• Allow the top layer to burn until it too develops the white ash coating on the black sticks.

• Now quench the fire by adding water. It will take more water than you might imagine, keep pouring it on until the pit is full or you’re certain the fire is totally extinguished. You can check by moving the top layers with a metal spade. The base should be cool. Do be very careful.

After the Burn

Remove the charcoal and break it up into small pieces. You can bag the charcoal and trample it or hit with a lump hammer. Or place into a strong large bucket or trug and pound it with a piece of wood. The finished product should pass through a garden soil sieve.

You’re now ready to charge your biochar prior to using.

Adding Biochar To Your Garden

With all of these benefits mentioned they do come with a word of caution. Biochar is not the answer to all of your problems in the garden and adding to much would not be beneficial.

By sparingly using it as an additive along with your normal regiment of doctoring you do to your soil it can have some long lasting great benefits. Sprinkle it on top of the soil, or mix it in prior to planting for the season. It’s up to you!