While we love to look at the plants growing above the ground, an essential component to thick, healthy greenery and beautiful, bountiful blooms is what lies beneath: the soil.
Soil supports plant and tree roots, filters rainwater, and stores the nutrients they need to grow.
When it comes to improving your soil, there are quite a few popular ways to do it, including with the addition of compost and mulch.
But a newer approach using a biochar soil amendment has become increasingly popular for its positive impacts on not only the soil, but also the environment.
Let’s take a look at how this treatment can improve your soil quality and help your plants.
Davey SoilCare®: What is Biochar?
Since it’s a relatively new term, you’re probably asking yourself, “What is biochar made from?”
Biochar is a type of fine-grained charcoal used as a soil amendment and created by slowly burning wood and agricultural byproducts, such as plant matter, with low oxygen in a process called pyrolysis. Carbon is absorbed within the growing organic material during photosynthesis, and then it is converted into a stable, solid form during pyrolysis, making biochar.
While the biochar soil amendment is a newer concept, researchers believe it was common for Amazon rainforest farmers to use it to successfully grow fruit trees and other crops.
Biochar Vs. Charcoal
If biochar is considered a form of charcoal, you might be wondering, “Is there a difference between charcoal and biochar?”
What is biochar made from? It’s a carbon-rich soil amendment that is derived from organic plant matter. Charcoal, on the other hand, is a carbon-rich element that is derived from biomass in a similar matter.
The key difference between biochar and charcoal is in how each product is used. Charcoal is used in cooking and industrial processes such as steel and silicon manufacturing. Biochar is used to improve soil properties for growing plants, nutrient management, and carbon sequestration.
Thousands of years ago, Amazon natives burned jungle plants and branches slowly, combining it with manure and household waste to enrich nutrient-deficient clay soil. What they learned is that unlike compost, biochar doesn’t decompose and continues benefitting the soil for many years.This is because the pyrolysis process fixes carbon into molecular forms which are not easily decomposed by soil microbes, allowing biochar to persist for thousands of years in soil.
The benefits of biochar in soil are numerous:
- Biochar holds water like a sponge, where plant roots can access it when they need it. This is especially helpful during periods of hot, dry soil conditions.
- Biochar helps conserve plant nutrients by storing them and making them readily available when plants need them.
- Road salt can increase the salinity of your soil, making it harder for plants to take up water and nutrients.This dehydrates plants, causing them to wilt or brown. Biochar absorbs and releases salts in the soil to be flushed away in a way that reduces the injury to plants.
- Biochar strongly resists compaction in soil, keeping channels open for water, air, and root movement even if there is repeated traffic on the surface.
- Biochar sequesters carbon, storing it in the soil and keeping it from decomposing and adding carbon dioxide to the atmosphere.
How to Use Biochar
Now that you know the benefits, learning how to add biochar to soil is the next step.
If biochar is being added to the soil for improvement, such as boosting aeration in a high clay or compacted soil, it can be incorporated into the root zones using air tools. It can also be injected into soil as a liquid slurry, used to establish deep drainage with vertical mulching, or top-dressed over newly-aerated lawns in a blend with compost.
Biochar application rates vary by application type:
- For vertical mulching, it is used as a backfill at a 100%
- When preparing landscape beds for planting, it can be mixed with 1 part biochar, 1 part compost, 2parts soil
- For air tool tillage, it is applied 1 part biochar, 9 parts soil (or compost)
- For lawn applications, it is blended 1 part biochar, 19 parts soil (or compost)
- For liquid applications, biochar powder is mixed with water at 1 part biochar, 39 parts water and then injected into soil under pressure
How Long Does Biochar Last in Soil?
Biochar soil amendment is believed to last quite a long time in your soil, ranging from 1,000 to 10,000 years.
This long life is credited to its high stability against decay.
Where to Buy Biochar
Now that you can see what biochar can do for your soil, your next research task is finding out where to buy biochar.
While you can find a lot of information online about how to try and make biochar yourself, the product is also available by direct order from manufacturers, at some garden centers and green industry suppliers , as well as through your tree care services provider. Your local arborist can properly apply the product so you can see how it’s done and ask questions to better understand this soil amendment along the way.