Biochar generally raises soil pH, especially in acidic soils, making it a useful amendment for managing soil acidity and improving crop productivity. In other words, you might not have to lime if you’re adding biochar to your fields.
Key Points
- Biochar increases the pH of acidic soils
- In alkaline soils, biochar has a buffering effect
- Most nutrients are plant available in a soil pH of 6.0-7.5
- Biochar benefits are dependent on feedstock, pyrolysis temperatures, application rate, and soil type.
- Feedstock has a big impact on the characteristics of the finished biochar
- There isn’t one biochar but multiple biochars, with properties that will benefit your application needs
- Soils with high fertility, organic matter, or low acidity show the least benefit from biochar application
- Sandy and degraded soils benefit from the addition of biochar + humates
- Soil test before and after soil amendment applications
Here’s a deeper look at how biochar affects soil pH and why it matters:
What Are the Impacts of Biochar on Soil pH?
In acidic soils, biochar tends to increase pH, acting as a liming agent. This helps neutralize acidity and creates a more favorable environment for plant growth. In alkaline soils, biochar can have a buffering effect. This helps stabilize pH and prevent extreme fluctuations.
In alkaline soils, there is a potential for biochar to increase pH, reducing nutrient availability. That would also disrupt microbial balance and intensify salinity issues. Biochar made from feedstocks like manure has the greatest negative potential, especially if overapplied.
What are the Benefits of pH Adjustment?
Nutrient availability often has the soil pH as a limiting factor. When you decrease the acidity of your soil, the nutrients already there, such as phosphorus, calcium, and magnesium, become available for plant uptake.
You also benefit by reducing aluminum toxicity while enhancing microbial activity. These benefits are dependent on biochar feedstock, pyrolysis temperatures, application rate, and the soil type.
A 2025 meta-analysis found consistent evidence that biochar application raised soil pH and improved crop yields in acidic soils. The long-term stability of biochar affects soil pH over long time spans.
But The First Question is: What Is Biochar?
It is a carbon-rich material produced by pyrolyzing organic matter (like wood or crop residues) in low-oxygen conditions. It’s highly porous and stable, making it excellent for improving soil structure, water retention, and nutrient availability.
There isn’t just one biochar. The characteristics of a biochar are determined by the feedstock used, the pyrolysis process, and the “charging” organics. Biochar, by itself, has no nutritional value, but it is a powerful ally in retaining moisture, attracting beneficial microbes, and decreasing nutrient leaching.
“Charging” means adding organic matter that is decomposing to the biochar. The odors we smell from any decomposing organic matter are nutrients escaping into the atmosphere, sometimes as greenhouse gas emissions. When biochar is added to a manure pile or compost bin, the gases are caught in its vast network of pore spaces. Those gases are stored as nutrient molecules, ready for microbe or plant food.
The short answer is that there isn’t biochar, there are biochars. Each has characteristics that may be just right for your soil. It’s wise for you to ask questions to make sure you’re getting the right fix for your problems.
Why Are There Different Biochar Characteristics:
The type of feedstock has a significant effect on the characteristics of the finished biochar. Biochar made from woody biomass will be more alkaline than biochar made from manure or crop residues. And biochars made from anything other than a single woody biomass will have pHs that vary widely depending on composition and pyrolysis process.
In this table are some common feedstocks and pyrolysis temperatures. Any organic matter can be used as a biochar feedstock, so always ask your supplier about feedstock and pyrolysis temperature.
The practical implications are that if you’re a blueberry grower, softwood biochar is your best bet. And the material you use as the charging agent will make a huge difference in maintaining the acidity of your soil.
For most crops, a neutral or slightly alkaline soil pH is preferred. If you have soil a blueberry grower would love, but you’re planting corn, a biochar made from almost any of the feedstocks listed above would be beneficial in your fields.
The beauty of spreading biochar with your cow or poultry manure is that you avoid the salinity issues that often come with years of manure applications. Biochar acts as a slow-release fertilizer for your crops, decreasing any salty buildup.
When you convert part of your manure load into biochar, you’re decreasing the volume of waste. If you then apply it on top of your manure, you’re capturing all the valuable nutrients that made it all the way through your livestock.
Choose the Right Biochar For Your Soil
Soils with high fertility, low acidity, or high organic matter show the least improvement from biochar applications. The soil already has a high carbon content. Look at a forest, for example. It has a thick layer of carbon-rich leaves decomposing on the surface, along with numerous microbes and earthworms that accelerate this decomposition.
The forest, if left undisturbed, continues to accumulate carbon on the forest floor, in the vegetation, and in the soil. Biochar wouldn’t add much in terms of soil structure, nutrients, or microbial life.
But what about your field? That is highly disturbed soil with little microbial life. It may be clay, sand, or loam, but the years of disturbance have destroyed the soil structure. A conventional field left bare all winter or after harvest experiences erosion from wind and water.
Incorporating biochar + humates or manures on your fields increases fertility. Taking the next step and sowing cover crops in a no-till system jumpstarts the benefits of the biochar.
Sandy soil tends to have particular problems with water and nutrient retention. Biochar alone can’t solve those problems. But when you incorporate compost, manure, or worm castings with the biochar, you increase the organic matter in the soil. The bochar creates soil structure to keep microbes and nutrients in the plant root zone. When you plant cover crops, their roots rapidly decrease erosion problems, as well as nutrient leaching.
Soil Test for pH To Determine the Best Biochar for You
Soil testing before you add amendments is wise. You may find your soil is deficient in certain amendments. The easiest way to add them is by incorporating nutrients as liquids or solids with biochar and applying them together. Micronutrients are often missing or deficient.
Biochar blends enriched with organic fertilizers are making waves for their ability to enhance soil health and plant growth. Biochar, a carbon-rich material produced from the pyrolysis of organic matter, serves as a robust soil amendment. When combined with organic fertilizers that contain essential components like humic acids, fulvic acids, and micronutrients, this blend not only improves soil fertility and balances soil pH, but also promotes long-term nutrient release.
The fulvic and humic acids work synergistically to enhance nutrient uptake by plants, improving their overall vigor and resilience. This slow-release mechanism ensures that nutrients are available when plants need them most, fostering sustained growth and supporting vibrant blooms throughout the growing season.
If you’re looking for a biochar blend that checks all the boxes for most soils, you’ll find it in one of our products. Our VITAL Blend line is biochar + humates for a balanced nutrient and conditioner soil amendment.
As a farmer or rancher, you may already have the charging materials readily available in the form of manure. Applying our NAKED Char on a manure lagoon or adding it to livestock bedding charges up the biochar with the nutrients that otherwise would have been lost.
This small addition to your farm or ranch routine cuts greenhouse gas emissions, improves soil health, and balances the pH for robust plant growth.
