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Biochar is a simple soil additive that stands to alleviate a host of environmental problems. Biochar acts as a catalyst for improved soil health and can remain active in the soil for millennia!

Figure 1: Biochar structure (Cool Planet, 2015)

What is biochar?

Biochar is charcoal used as a soil additive. It is found in the form of powder or small chunks. By burning biomass (wood, grass clippings, manure, etc) at high heat with limited oxygen, charcoal is created with a strong grapheme structure. Graphene is a sheet of carbon rings, which join to look like chicken wire (see Figure 1). In this form, it takes thousands of years to break down. (McLauglin, 2010, p. 69)

What’s all the hype about?

Biochar locks carbon into the soil that would otherwise be released into the atmosphere as a greenhouse gas. When burned properly, biochar is a carbon negative product!

Biochar strengthens microbial and plant life in the soil in two ways:

  1. By providing space for fungi and bacteria to grow,

  2. By attracting and holding water and essential nutrients, creating a moist and fertile environment for microbes and plants to thrive.

Soil improvements from biochar increase overtime because microbial life continues to grow, which in turn improves water and nutrient retention, and the ecosystem’s defense against pests and disease. Thus, overtime, biochar will decrease the need for fertilizers, pesticides, and irrigation while growing healthier, more vibrant plants.

Volunteer mixing Wakefield Biochar into soil at Cloud 9

How do I use biochar?

Biochar should be allowed to soak up nutrients from compost or other available materials before adding it to soil. Because biochar is such an effective magnet for nutrients, it can lock up nutrients in the soil for a period of time if it is not introduced to the soil ecosystem with a network of microbes and minerals already enmeshed. (Wells, 2010, p. 40) Once biochar is inoculated with nutrients and microbes it is ready to be used as a top dressing, in potting soil, or tilled into your field. It is up to you how you choose to mix it in.

How does Cloud 9 use biochar?

On the roof of Guild House West, Cloud 9 is using a lightweight soil mix made of equal parts biochar, compost, and leaf mulch. Our mix uses biochar at a much higher concentration than we would recommend using in garden mixes less limited by weight. Biochar offers a lightweight structure for a healthy soil ecosystem to grow and thrive in within the weight requirements of a rooftop environment.

Radishes sprouting in our biochar mix
Radishes sprouting in our biochar mix

In a natural ecosystem, bacteria, fungi, worms, and other critters make the materials from dead plants and animals available to growing plants as nutrients. Our rooftop garden does not have access to a larger soil ecosystem, and so we must foster it within our growing containers. Biochar provides the structure within which bacteria and fungi thrive, which in turn supports the life of our crops, which support the health of our human bodies as the micro-organisms distribute nutrients throughout our ecosystem.

Want some biochar?

Order from Wakefield Biochar! High quality biochar sourced regionally!

Biochar References

  1. The Science of Cool Terra ™ Biochar. Cool Planet Energy Systems. 2015.

  2. Taylor, Paul (Ed.). (2010). The Biochar Revolution. Mt. Evelyn, Victoria, Australia: Global Publishing Group.

  3. Lehmann, Johannes, PhD. Biochar for Environmental Management: Science and Technology.

  4. The International Biochar Initiative,

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