Taking care of the soil is one of the most important tasks in an organic garden.
The soil web allows for the transmission of nutrients to plant roots, the recycling of organic matter, and the flow of water through the landscape.
Biochar is a resource which can allow you to add fertility to the soil and improve its structure and water retaining capacity.
While biochar has been used for centuries, it has recently enjoyed something of a resurgence in the organic gardening field.
In this article, we will discuss how to make your own biochar to help fertilize your garden.
The use of biochar is one of the important trends that has emerged in sustainable food growing – on both a domestic and commercial scale – in recent years.
There is a growing awareness of the need to develop more sustainable methods of organic growing, and of the need to develop solutions for the greenhouse gas emissions that are causing global warming.
Biochar has been touted as a potential solution for both of these issues, as well as the growing issue of global waste.
Why not get in on this interesting trend and do your part for our planet by creating your own biochar from organic waste materials where you live?
What is Biochar?
Before we take a look at how we can make biochar, we should begin by developing an understanding of what biochar actually is, and why it is used.
Biochar is a word derived from the words ‘biomass’ and ‘charcoal’.
While the practices involved in making it and using it have been used for centuries, such as by Native Amazonians, the word itself dates only from around the 1990s, and only entered into common parlance in the last couple of decades.
Biochar is charcoal that is produced by heating wood, grass, straw, bracken or other organic ‘waste’ materials in the absence of oxygen. This leaves behind charcoal that is rich in carbon, porous, and able to retain nutrients incredibly effectively.
This charcoal is enriched with the addition of richly fertile organic material and placed into the soil to create a fertile growing area.
Why Make Biochar?
Biochar is not only a way to improve the soil in your garden, add fertility and improve moisture retention. It is also an important and effective way to combat global warming through carbon sequestration.
In recent years, scientists have identified the use of biochar as a potential solution for the mitigation of climate change caused by greenhouse gas emissions, as well as a way to reduce waste and increase organic food production – especially in areas with poorer soil fertility.
Interestingly, biochar can sequester more carbon than simply composting organic waste or woody matter from your garden.
Composting only sequesters around 10-20% of the carbon in the material, while creating biochar sequesters around half of the carbon that would otherwise be released.
Studies suggest that biochar beds or fields create stable carbon sinks long term, which has the potential to put a huge dent in carbon dioxide emissions.
How Biochar Can Add Fertility
You may be wondering how exactly adding charcoal to your garden can add fertility.
The key factor is the structure of the carbon rich charcoal you can create through oxygen-less heating. If you have ever seen a piece of charcoal, you may remember that it is a brittle material, filled with hollows and minute cracks and fissures which create an airy and porous structure.
This creates a sponge-like structure which is good at absorbing and retaining water and nutrients that are introduced to it.
In addition to creating a structure for enhanced water and nutrient retention, biochar can also add improve fertility by reducing soil acidity, adding potassium which is necessary for healthy and productive plants, and creating a soil habitat conducive to good bicrobial health – making sure that the micro-organisms in the soil can thrive and do their jobs.
In addition, there is some suggestion that biochar can deliver a degree of protection against certain foliar and soil-borne diseases.
Once placed in the soil, charcoal debris is spread through the soil through the agency of earthworms and other soil biota.
The History of Biochar
Pre-Colombian Amazonian tribes created what became known as terra preta (Amazonian black earth), which allowed them to increase their yield when growing crops.
This was an early model for the use of biochar as a soil amendment.
Early civilisations in the Americas would dig large earthen pits and fill these with food scraps and agricultural waste. They would then set all this waste on fire and cover it with soil – in much the same way as in the pit method described below.
The secrets of these civilisations were forgotten by many. But in more recent years, there has been growing awareness of the pockets of more fertile land created by these ancient practices, and growing interest in sequestering carbon by introducing the use of biochar more widely in food production.
There are a number of different ways to create the charcoal required to make the biochar to fertilize your garden.
The simplest methods for home growers are described below:
In A Pit
The easiest way to make biochar is in the ground.
Native peoples in the Americas used this technique to create more fertile growing areas.
After you have harvested summer crops from a growing area, dig a pit and fill this with wood. Next, simply set this alight and cover it with a blanket of soil to exclude oxygen. Once the area has stopped smouldering, you will discover that charcoal has been created below the ground surface.
While some oxygen may have reached the material, you will still find that most of it has converted to charcoal as required.
With a Clay Charcoal Oven
Another way to obtain charcoal without having to dig up your growing area involves using primitive techniques and garden resources to create a charcoal ‘oven’.
- First, Make a tipi-like stack of wood and cover it with mud/clay, leaving a hole open at the top. (You could use clay from your own garden, perhaps.)
- Next, make temporary ventilation holes around the base.
- Light a fire at the top and allow the fire to spread down through the structure.
- When you see flames through the holes at the base, block all the holes to exclude oxygen.
- Leave overnight.
- The next day, create a door in the oven and break it open to retrieve what remains inside. There will be some partially combusted wood and ash, but should also be plenty of charcoal. You can then reuse this mud/clay structure to make more if you wish.
With a DIY Burner
There are, of course, also more modern ways to create charcoal.
Many gardeners and growers, for example, have successfully made their own DIY charcoal burners. Charcoal burners often involve placing one reclaimed metal drum inside a larger one.
Often, smallholders and sustainable farmers and gardeners are recycling other forms of waste to aid in the creation of biochar, and developing systems for sustainable charcoal production which minimises all forms of pollution and waste.
Some more sophisticated DIY burners even make use of the gases released through the process for energy or heating.
If you plan on creating a quantity of biochar for your property, you might like to look into one of these more sophisticated DIY charcoal making systems.
How To Turn Charcoal into Biochar
Turning charcoal into biochar involves ‘inoculating’ it with a fertile solution.
In the pit method, once the area has stopped smouldering, this might involve simply watering the area with a nutrient rich compost tea, which will be absorbed by the porous charcoal.
In the other methods of charcoal production, it often involves steeping the charcoal in such a liquid solution.
Making compost tea or another liquid feed to be absorbed by the charcoal you have made is easy.
Simply place some home made compost, or organic materials in a bucket of water, with a lid, and leave it to decompose for a few weeks.
It will become a stinky brew.
Simply pour this over your pit bed, or soak the charcoal you have made in this brew, then add the pieces to your garden beds.
You could also consider making a liquid feed from comfrey, seaweed, or other plant materials from your garden.
Another option is to use the liquid run-off from a wormery, if you use vermiculture to compost food scraps and create a fertile soil amender for your garden.
If you are sold on the benefits of biochar for your garden, but you don’t want to – or aren’t able to – make your own, then you can buy biochar online.
This 7.5 Gallon Bag of Wakefield Biochar Soil Conditioner is the best option available online, although some more biochar options are presented below.
The Final Word
Biochar is a useful resource for organic gardeners, whether it is bought, or you make your own.
By using it in your garden, you will not only be improving the soil fertility and making it easier to grow your own in less than ideal conditions, but will also be doing your part to sequester carbon and aid in efforts to mitigate greenhouse gas emissions and climate change.