Getting gardens to reach their optimum fertility level is difficult. However, high-quality soil amendments for your garden are easier to find than you think. In fact, they might be as easy to access as your brush pile out back. By turning wood debris into biochar and putting it in your garden, you can improve your garden soil, increase the number of nutrients available and even help to combat global warming. And, all through a process as simple as having a bonfire.
Since it’s simple to make and easy to use, biochar might be the natural fertility solution your garden needs. Read on to learn more about this technique and how you can use it to produce your healthiest plants yet.
What is Biochar?
A simple definition of biochar is that it is a form of charcoal used specifically for agricultural purposes. Wood or similar biomass is burned in a low oxygen environment so that charcoal forms in a process called pyrolysis. The fire is put out before the charcoal is burned down into ash. Furthermore, the final product of charcoal is full of tiny crevices and holes that are the perfect living spaces for soil microorganisms.
The native peoples of the Amazonian rain forests are credited with discovering the benefits of biochar over 2000 years ago. Although, the technique was forgotten after European explorers introduced diseases to the region that completely wiped out the native populations. At the height of its effectiveness in the Amazon, biochar was used to turn agricultural waste products into a soil enhancer that held carbon, produced better-growing conditions and increased the soil fertility of the notorious infertile tropical soils.
Today, biochar is found in soils around the world due to natural forest fires. Studies of the technique in the Amazon are starting to reveal just how beneficial this soil practice can be for fragile agricultural systems.
How does Biochar benefit the soil and crops?
When applied correctly, biochar has enormous benefits for the health of your garden soil. Not only that, proponents also claim that it can be a big help in combating global warming.
Good For The Soil
It’s not the charred pieces of wood themselves that add so much benefit to the soil, but rather the combination of the bacteria they attract combined with compost and organic fertilizers. Once the surfaces of biochar have properly ‘weathered’ they become home to beneficial microbes in the soil. Essentially, this is because the charred pieces of wood provide ideal living spaces within their nooks and crannies. The highly porous structure of biochar helps it to absorb both water and nutrients within its many microsurfaces. Thus, keeping these resources deep in the soil and improving growing spaces for the types of bacteria that process these nutrients into forms that are accessible for plants to take up.
Soil that has been treated with biochar becomes more resilient and has a better tolerance to droughts as well as root and leaf diseases. Biochar can also help to improve the water quality of the soil. This is done by creating a binding agent for nutrients to fuse, preventing them from getting washed away in groundwater during heavy rains.
Good For the Earth
Not only does biochar make a positive difference in your garden bed, but it can also actually make the entire planet a little healthier. Conventional agriculture has some extreme impacts on the world’s soil quality, and tilling up huge portions of the ground tends to release greenhouse gases into the atmosphere that had been sequestered into the soil. Because soil retains 3.3 times more carbon than the atmosphere, it is an important carbon sink and the release of carbon through agriculture can be devastating.
Biochar is a smart way to start to combat this problem. Studies have shown that charred wood is a stable substance that takes thousands of years to break down, making it a sustainable way to store carbon. There is talk of creating biochar in developing countries and storing the end result deep into the soil in order to sequester carbon. The resulting heat from the burn process can also be harnessed in a wide variety of ways. Though this technique hasn’t been adopted large scale yet, the potential is high for a large scale biochar project to make a big difference in worldwide carbon levels.
The early evidence is clear. Biochar has the potential to dramatically increase the fertility of your garden soil as well as make the entire planet a slightly more sustainable place.
Where is Bio-Char Sourced From?
The process of making biochar may be simple, but the science behind it is actually quite complex. There are lots of variables associated with making biochar. These include the type of material burned, the heat at which it is burned and the length of time that it is burned for.
If you want to use biochar, one option is to buy charcoal from biochar companies and pulverize it yourself. Most of the biochar you can buy from garden supply stores comes from large ‘industrial’ wood burning operations that often use tree debris from neighborhoods.
However, making your own biochar is so simple that you have few excuses for not producing it yourself.
Making Your Own Biochar
All it takes to produce your own biochar is burning wood until it is partially burned through, or becomes charcoal. You can make low heat brush fires in your backyard and pull out logs once they have turned black and charred for a steady supply.
Combing through some campground fire pits is the perfect way to accumulate an unlimited amount of biochar. That is so long as you are willing to go through old fire pits in order to find it. All you need to do is collect the partially burned logs, smack them with a shovel into smaller pieces, and store them until you are ready to add it to your soil.
In order to make your biochar, start by digging a trench in your backyard. Pile brush up into the trench and start a fire. The goal is to create a hot fire that eventually slows down due to a limited oxygen supply. A good way to tell how well your fire is doing is to watch for smoke. The early white smoke is caused by water vapor dissolving. However, the later yellow smoke indicates that the sugars in the wood are starting to burn.
Once the smoke turns grayish blue you know that the charcoal stage is happening, at which point you can dampen the fire with an inch of soil in order to cut off the oxygen supply so that it will smolder instead. Observe the fire until you see that the wood has burned down into charcoal chunks, and dose the fire with water so that it stops burning.
Once the pieces of charcoal cool, you can pulverize them into small pieces and store them in a bucket until you are ready to apply them to your garden.
General Application Rates
In most cases, biochar isn’t ready to be used in the garden immediately after being burned. This is due to it usually needing to be further processed in order to make it more appealing to soil bacteria. You can briefly compost your biochar or soak it in compost tea in order to fill the pores of wood with beneficial nutrients and bacteria. After a few weeks, this processed biochar will be ready to go into the garden.
The optimal amount of biochar to add to the garden is still contested by researchers. In general, it seems that the more you add the greater the benefits are for your soil, to about one pound per two square feet, though significantly smaller amounts can still make a big difference.
To apply your biochar, simply mix it with compost and apply it to the top of your garden soil. Just make sure you mix it in the top six inches. You can apply a similar amount for several years until the level of biochar has built up in the soil to the rate where you can see it whenever you plant.
Additional Resources for Using Bio-Char
Using biochar in the garden is a fascinating process full of opportunities for experimentation. If you are looking for extra ways to perfect your biochar technique, simply follow these tips for success.
- You can use other forms of charcoal (like rice-hull charcoal) besides wood for biochar. Although, it’s smart to avoid industrial charcoal. This is because it can be filled with nasty chemicals you don’t want in your soil.
- Bones and food waste can also be burned for use as charcoal in the garden. Because bones are a great source of phosphorus, they are an easy way to round out the nutrient value of your soil.
- When it comes to biochar size, the finer the particles the better. This is because the more surface area creates extra space for bacteria to grow. However, making your biochar too fine can pose a problem with dust. Be sure to keep that in mind when pulverizing it.
- Biochar tends to be as alkaline as lime. This means it might not be a smart soil additive for naturally acidic soils.
- Too much biochar can pose a problem for gardens by raising the alkaline levels beyond what plants can handle. So, don’t forget to be mindful of your soil’s pH levels when deciding how much to add.