Gorman Heritage Farm produces biochar from fallen trees here on the Farm. Biochar can be purchased in our Farm Shop for use in your home garden.

Biochar is a type of charcoal. It is made with the purpose of being added to soil to improve overall agricultural productivity, including functions such as soil health and plant growth.

Charcoal is created from the carbonization of biomass. There are two main processes: pyrolysis and gasification — our kiln makes charcoal using pyrolysis. Pyrolysis bakes the biomass in the absence of oxygen (400 – 1400°F) driving off volatile gases and leaving behind charcoal. Gasifcation is a similar process that occurs at much higher temperatures (900 – 3000°F) and also produces synthetic gas and oils as a byproduct. These processes involve a combination of time, heat, and pressure that vary between equipment and types of feedstock. A typical feedstock is wood, but other materials such as rice hulls, peanut shells, manure, and honeysuckle are used.

Humans have been making charcoal for thousands of years in earthen

pits and mounds. Archaeological evidence suggests that the ancient Amazons burned biomass and other forms of waste to create a special type of soil called Terra Preta. Meaning “BLACK EARTH,” this carbon-rich soil included a mix of charcoal, pottery shards, plant residue, animal feces, fish, and animal bones. This human-made soil was crucial to the large-scale agriculture that supported Amazonian civilizations.

Archaeologists used to believe that Amazonian soils were not suited for

agriculture, as they endured intense heat and rain — leading to erosion.

As a result, the soil would have been weathered, acidic, and lacking essential nutrients. This low-quality soil would have prevented the creation of complex agricultural societies. We now know this theory to be incorrect. Soil sampling and archeological evidence prove that much of the Amazon basin consisted of fertile soil that was farmed by the First Americans. This carbon-rich soil is a result of biochar production and its role in the creation of Terra Preta.

One of the environmental benefits of biochar is that it transforms biomass into carbon that then becomes locked into the soil. Plants take carbon out of the atmosphere during photosynthesis. When a plant dies the stored carbon typically decomposes and returns to the atmosphere. Through the process of pyrolysis, we can capture some of this carbon in the form of biochar — thus removing it from the atmosphere. As long as the carbon remains stable in our soils, it is a form of sequestration and a mitigator of climate change.

Decades of research in Japan and recent studies in the U.S. have shown that biochar stimulates the activity of important soil microorganisms that affect the microbiological properties of soils. The pores in biochar provide a suitable habitat for these microorganisms by protecting them from predation and drying while providing them with energy and mineral nutrients. Soil organisms affect soil ecology and provide many ecosystem services. Studies have shown some of these soil organisms consume nitrous oxide and methane — two very powerful green house gasses.

The incorporation of biochar into soil improves soil fertility for the longterm. Used alone, or in combination with compost, manure and other amendments, biochar can increase crop yield. As a stable form of carbon, biochar remains in the soil; a single application can provide benefits over many years. The specific benefits include:

  1. Builds soil structure, increases space for plant roots, worms, and microorganisms.
  2. Increases water retention, aeration, and tilth (fluffiness and workability of soil).
  3. Promotes higher cation exchange between plants and soil (better nutrient uptake).
  4. As a solid and stable form of carbon, biochar is a method of carbon sequestration.

It is important to note that not all biochar is the same. The key chemical and physical properties of biochar are greatly affected by the type of feedstock being heated and the conditions of the pyrolytic process. For example, biochar made from manure will have a higher nutrient content than biochar made from wood cuttings. However, the biochar from the wood cuttings may remain longer in the soil. The two biochars will appear similar but will behave differently.

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Funding for the Gorman Heritage Farm Biochar was generously provided by Debbie Clark and the Rettig Foundation Trust.