Make your own biochar
In gardening and agricultural circles there is a lot of discussion about biochar these days. You can spend lots of money on small bags to add to your garden from a number of commercial sources.
For our purposes there are two kinds of biochar that you will hear about; ordinary biochar and so called activated biochar. the first type of biochar is charcoal that is procuced under low oxygen conditions. Activated biochar when correctly produced goes through an additional rapid temperature change or "quenching" which results in “activation”.
You might hear about soaking biochar in worm wee or compost/seasol etc, this is not activation in any accurate or scientific sense, nor in our opinion is it likely to improve the product.
For the purposes of gardening and potting, standard biochar is fine. proper activated biochar is more suitable for filtration and purification to remove pollutants, this is overkill for garden use.
Biochar is not a necessity to have, and healthy soils will perform very well without it, however it has proven to be beneficial for home gardens and a useful addition to potting media.
It has been shown to help retain and store essential plant nutrients, making critical nutrients more available to plants over a longer period of time, biochar plays a role in stabilising soil pH, it helps to retain water making this a useful additive for sandy soils,
Biochar assists in aeration of the soil and helps to build soil structure which reduces compaction, and lastly, biochar is a great for carbon sequestration, reducing your carbon footprint.
To add biochar to your soil it is really quite simple. You just throw it about. In practice we try to place it on the surface of our soil before mulching. What is tricky is knowing how much. Unfortunately this is like a piece of string but a good general rule for a good soil I have found 2 handfuls for a 3x1.5m bed is enough, this may be applied annually if desired.
I am going to show you a very simple method to make your own. It costs a fraction of the commercially made biochar and you can make as much or little as you need. A friend of our family, Warren Brooks, a prominent Orchid grower, has created instructional guide to make your own biochar, the youtube video is here and below is a photo guide. Orchids With Warren
Warren uses old coffee or milo tins, start asking your friends to keep their old tins for you. Drill holes into the bottom of the tin to allow some air in. Not too many though.
For this example Warren is using fruit tree prunings. Find some wood that is around your thumb thickness and smaller. The thicker the wood is the harder it is to smash later. In Warren’s video he uses mulch and walnuts as they are easy to crush.
Cut the wood to fit the size of the tin that you are using.
Until you have filled all your tins with prunings. Fit the prunings together as tightly as you can.
Add a hole in the side of your tin. This must be accessabile with the lid closed. This hole allows you to pick up the tin with some pliers and place into a fire.
Put the lid on tightly.
Place the tin in the fire. This fire is a home wood heater. Put the tin in the wood heater and leave it overnight.
Time to smash. Break the biochar down to workable chunks.
It really is that simple. If you have tins and a fireplace.
