Biochar use in gardens

What is Biochar?

Biochar is a type of charcoal that is made from biomass, such as wood, agricultural waste, or grasses. It is used as a soil amendment to improve soil fertility and plant growth, and as a carbon sequestration tool to reduce greenhouse gas emissions. Biochar can also be used as a filter for water and air purification. The production of biochar creates a by-product called bio-oil which can be used as a fuel source.

Biochar is made by heating biomass, such as wood, agricultural waste, or grasses, in the absence of oxygen. This process is called pyrolysis. During pyrolysis, the biomass is heated to high temperatures (typically between 300 and 700 degrees Celsius) in a sealed chamber or kiln. The heat causes the biomass to break down into three main components: biochar, bio-oil, and syngas.

The biochar that is produced during pyrolysis is a highly porous, carbon-rich material that can be used as a soil amendment and a carbon sequestration tool. The bio-oil and syngas can also be used as fuel sources.

There are different types of pyrolysis kilns that can be used to make biochar, including:

  • batch kilns: which are small, portable kilns that can be used to make small amounts of biochar
  • continuous flow kilns: which are larger, industrial-scale kilns that can be used to produce biochar on a commercial scale.

The process of making biochar can also vary depending on the feedstock used, the temperature, and the duration of the pyrolysis process. These variations can affect the properties of the biochar produced, such as its pH level, nutrient content, and porosity.

In addition to these traditional methods, there are also new methods being developed, such as using microwave pyrolysis and supercritical water pyrolysis, that aims to make the process more efficient, cost-effective and sustainable.

How is Biochar used in gardens?

In gardening, biochar is used as a soil amendment to improve soil fertility and plant growth. It is added to the soil to increase its ability to retain water and nutrients, improve the soil structure, and promote the growth of beneficial microorganisms.

Biochar is also known for its ability to act like a sponge and hold onto nutrients and water, making them available to plants for a longer period of time. It also promotes the growth of beneficial microorganisms, which help to break down organic matter and release nutrients into the soil. This can lead to more vigorous plant growth and increased crop yields.

It is also used to reduce the acidity of soil, and it can be used to improve the health of plants suffering from heavy metal toxicity.

Biochar is typically added to the soil at a rate of 1-5% by volume, and it can be mixed into the soil before planting or applied as a top dressing. It is important to note that biochar should be added to the soil after it has been properly prepared and the pH has been adjusted as needed.

Biochar is a very porous material and it can hold onto nutrients and make them available to plants over time. However, biochar itself does not contain many nutrients. It is typically low in nutrients such as nitrogen, phosphorus, and potassium, which are essential for plant growth.

Biochar can be used to adjust the pH level of soil. It is typically neutral to slightly alkaline, with a pH of around 7.0-8.5. This can be beneficial for plants that prefer slightly alkaline soils, but it may not be suitable for plants that prefer acidic soils.

It is important to note that the pH level of biochar can be affected by the feedstock used to make it and the production method. Therefore, it’s recommended to check the pH level of the biochar before using it in gardening and adjust the soil accordingly.

It’s also worth noting that biochar’s properties may vary depending on the feedstock used, the method of production, and the conditions under which it was produced. Therefore, it’s important to conduct a soil test before adding biochar to your garden to determine the appropriate application rate and any potential nutrient deficiencies.