Hey there! Some links on this page are affiliate links which means that, if you choose to make a purchase, I may earn a small commission at no extra cost to you. I greatly appreciate your support!
(Last Updated On: March 15, 2022)
Biochar is a soil conditioner used for improving soil health, and it’s really increased in popularity over the last several years.
It is used by many market gardeners as a garden soil conditioner, and it may be a great idea for your garden!
Soil conditioners are materials that are added to soil in order to improve its quality. They can help to retain moisture and nutrients in the soil, suppress weed growth, and can reduce the need for fertilizers and pesticides.
Some common soil conditioners include biochar, compost, peat moss, and vermiculite.
Read on to learn all about biochar: how it’s used for improving soil health and how it can benefit your garden.
What is Biochar?
Biochar is a material that is made from the carbonization of biomass.
The simple definition of biomass is the organic material created by plants and animals.
Biomass is any organic matter that can be used as fuel, such as wood, plant material, crop wastes, or manure. Biomass was the main source of fuel worldwide until the 1800s.
Biochar is created by heating up that biomass to extremely high temperatures in the absence of oxygen.
This extreme heat breaks down the material into pure carbon. There are microscopic channels throughout all the tiny carbon particles.
These tiny channels hold onto water and nutrients, so biochar literally SUPER CHARGES soil. It’s as if it gives soil superpowers.
What is the difference between biochar and activated charcoal?
Biochar is similar to charcoal, but they aren’t the same. Resist the urge to use your charcoal briquettes as a fertilizer, and save them for grilling!
Biochar and charcoal are both made using a pyrolysis process, but biochar is created at a much higher temperature than charcoal.
That higher temperature leads to extremely high porosity and surface area within the biochar.
Biochar also has a negative charge, which helps attract and hold positively charged water and nutrients.
The negative charge of biochar increases its cation exchange capacity, which is just a fancy way of saying that the negative charge attracts positively-charged nutrients and water.
Biochar is made from the pyrolysis (brought to high heat in the absence of oxygen) of biomass, while charcoal is made from the rapid combustion of biomass.
The slow pyrolysis process at a high produces a material with a high carbon content that can be used to improve soil health. This slow pyrolysis process also creates tiny channels that increase the surface area an incredible amount.
Should You Use Biochar in your garden?
When used in conjunction with other healthy soil practices, biochar can be a powerful soil amendment for improving the long-term health of your garden.
Biochar helps to retain moisture, nutrients, and any added organic fertilizers. Biochar also increases the ability of soils to support plant life by increasing their porosity and aeration. All of these factors contribute to good soil, healthier plants, and increased garden production.
The benefits of biochar last for years in your soil, making it a very cost-effective soil conditioner.
Creating biochar also locks away carbon so that carbon does not get released into the atmosphere as part of the carbon cycle. This indicates that biochar production could help slow climate change and help combat global warming, at least in theory.
Is biochar better than compost?
The short answer is no. Biochar is not better than compost. The two serve different purposes.
Compost is a great way to improve soil fertility and add organic matter to your garden.
Biochar causes your soil to improve its ability to hold moisture and nutrients.
Adding both compost AND biochar is the best way to get the most benefit for your garden. When people add biochar to their garden, they usually add it by mixing it with compost and then adding that mixture to their soil.
Can you use too much biochar in your garden?
It is quite difficult to add more biochar than your garden can handle.
In cases where the soil is extremely poor, mixes of 50% compost/ 50% biochar have been added to soil with no issues.
A good rule of thumb is to add 1%-15% biochar to your soil volume, but you won’t hurt your soil if you use more than that.
Biochar won’t hurt soil microorganisms, damage the soil food web, and isn’t a chemical treatment.
Good quality biochar use doesn’t add anything but carbon to your soil.
How much biochar should I add to my garden?
The amount of biochar you need to add to your own garden will vary depending on the size of your garden and the type of soil you have.
A general rule of thumb is to add about an inch of biochar to the topsoil in your garden and mix to a depth of 6-12 inches.
You can also mix biochar into the soil at the plant roots before planting vegetables or flowers.
Another way to add biochar is to sprinkle it onto the soil’s surface and work it into the top few inches.
You may need a heavier application of biochar if you have clay soil that has not been conditioned lately or if you have sandy soil, because sandy soil has trouble holding water or nutrients.
A typical application rate of biochar is 1 pound of biochar per 1000 square feet of existing garden space. So for 1500 square feet of garden space, you’ll need around 1.5 pounds of biochar.
What does "charging biochar" mean?
Charging biochar is the process of adding fertilizers, nutrients, microbes, and water to the biochar and letting it sit to absorb into the biochar before adding to soil.
Since biochar has a high number of microchannels in each particle, these additives and soil amendments soak into the pores of the biochar.
Then, when it is added to the soil, it will release these nutrients over time back into the soil.
You don’t have to charge biochar for it to be effective, but charging it takes its powers in your soil to a whole new level.
You could try charging it with compost tea, worm tea, or other organic amendments to add nutrients to it before you add it to your garden beds.
Can you make biochar at home?
The answer is yes, but it is very difficult to control the process. When making biochar, you have to have extremely uniform biomass and plant material as inputs.
To create biochar, you also need to completely cut off the oxygen supply in the chamber you use to heat up the biochar. Some people use metal drums to make biochar, and others dig trenches to burn the biomass over several days.
You also need a large quantity of wood chips or other materials to ensure that your product is consistent throughout.
Meanwhile, biochar is readily available to purchase at an economical price. Unless you are on an extremely tight budget with more time than most people, it’s probably NOT worth your time and resources to attempt to gather the raw material to make your own.
However, if you do choose to make your own biochar, there are some things you must take into consideration.
First, the temperature of the biomass (plant waste or other organic materials) must reach higher than 450 degrees.
If the biochar does not reach that temperature, studies show that it could actually repel water instead of absorbing it.
What to look for when buying Biochar
When purchasing biochar for your garden, there are a few things to keep in mind. The pH of the product is important and so is the actual blend of the product you are purchasing.
Check the pH
The pH of biochar products on the market can vary, so you need to be sure of what you are purchasing.
Biochar can vary widely in pH from 4-12, but the best biochar is near the neutral range of 7. You don’t want the biochar to change the soil pH, especially near your acid-loving plants.
Pay attention to product blends
Read the product labels very closely when buying biochar for your garden.
Some products are nothing more than a charcoal blend, which will not provide the benefits of biochar. Look for products that are specifically labeled as “biochar.”
Other products are combined with compost, mycorrhizae, or another type of soil amendment. There is no problem with using these preparations, but make sure you read labels carefully so you purchase what you intend.
Most pure biochar costs around $2-3 per pound, with each pound treating roughly 1000 square feet of garden space.
This makes biochar one of the more affordable soil amendments available to gardeners.
In addition, unlike other soil amendments that must be applied annually, biochar can last in the soil for years or even decades.
Biochar Products Available for Purchase
Biochar can be purchased from many garden stores or online retailers. The cost of biochar varies depending on the type and quality of the product. Also, biochar is sold as a completely pure biochar or it can be pre-mixed with various soil amendments so that you don’t have to take that additional step to “charge” the biochar. Just make sure you check the product information thoroughly before you purchase.