What is biochar?

Biochar grains on the left and under an electron microscope on the right.

Biochar is a black, fine-grained, lightweight and highly porous form of carbon very similar to charcoal. The word biochar is derived from the Greek word bios, “life” and “char”.

Approximately 70 percent of its composition is carbon, which makes it a very pure form of carbon. The remaining percentage consists of nitrogen, hydrogen and oxygen among other elements. The bonds between carbon atoms are very strong  and difficult to break down which means biochar is stable, long-lived and resistant to weathering and decomposition by microbial communities.

Biochar is created by heating biomass to high temperature in a low oxygen environment. This process is called pyrolysis. Almost any biomass can be used but typical feedstocks include wood and plant matter. During pyrolysis the biomass starts to break down at a molecular level and volatile gases are released. These gases are either directly combusted or condensed in a clean and efficient process to generate various forms of energy. Approximately half of the carbon is released during the process; the other half is trapped within the biochar as a stable form of carbon.

Mankind has used biochar for millennia and today it is actively used by farmers in Europe, America and Japan.

Benefits to soil

Biochar enhances overall soil structure enabling plants to develop strong and healthy root systems.

Its highly porous structure acts as a sponge for water and nutrients, providing a home for beneficial microbes and fungi which improve soil fertility and crop yield.

Biochar remains in the essential root area and won’t wash through the soil like other amendments. It resists weathering and decomposition by microbes. Therefore, it is typically a one-time application.

Production of biochar results is carbon sequestration as carbon is locked away in the soil for centuries. This means biochar has the potential to help mitigate global warming and climate change.

Ash which forms part of biochar is alkaline. Therefore, adding biochar can help reduce soil acidity.

Lightweight, stable and long-lasting. Biochar adds bulk to soil and helps improve tilth and aeration. oHigh water-holding capacity. Biochar particularly improves sandy soils that struggle to retain water.

Biochar acts like a sponge absorbing excess nutrients and mitigating soil leaching.

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