Chris Savage, Vice President Loving Garland Green

Notes and More on Soil Improvement with Charcoal

Last night, Chris Savage, Vice President of Loving Garland Green, made an interesting presentation at our weekly meeting on the topic of Terra Preta (“Black Earth” in Portuguese).  Chris has been experimenting in his own garden for the past few years with the development of Terra Preta.

Terra Preta is a type of dark soil that is found in several countries in South America (particularly in the Amazon) and beyond.  It consists of up to 9% charcoal, pottery shards, animal manure, fish and animal bones, plant compost.  The ingredient not often found in various soil mixes is charcoal.  Yet charcoal, according to research from Cornell University, is the magic ingredient that makes the difference. Bio-char, it turns out, is very stable in the soil and it is believed to provide and retain nutrients for millennia.

Because of the high fertility of Terra Preta, continuous cropping for longer periods of time appears to be possible from a soil fertility point of view. How long a field can be continuously cropped and what can be done to prolong this period is not yet clear. Petersen et al. (2001) reported that Terra Preta soils in Açutuba were under continuous cultivation without fertilization for over 40 years. [Source: accessed May 19, 2015]

Arbuscular Mycorrhiza, an important soil microbial fungus that attaches to the roots of plants, performs a function similar to saliva in the human mouth:  it begins the breakdown of the nutrients in soil so that plants with vascular systems can better absorb these nutrients.  Apparently this fungus particularly likes charcoal as it is found in abundance in Terra Preta.

Other sources for information in this article:  Science Brief from Cornell University. - accessed May 19, 2015]



After creating/purchasing your fresh carbon, it must be charged by soaking it in a nutrient tea (such as compost or worm tea) prior to use.

1. Make your Bio Char the Hard Way

Here one way to make your own bio char, but check with local burning permits and your fire department prior to attempting to do this.   Frankly, this looks like too much work for me.   Make Your Own Bio Char and Terra Preta: 
[ - Accessed May 19, 2015]

2. My Potential EZ Way

I may experiment with this method.  This way I don’t have to worry about breaking any burning laws:  Partially burn a log in one’s fireplace and then pour water on it when it is about half-way burned.  Chop that up and then add at the rate of 9% to your existing garden and see what happens.  [Note:  Key word is “potential”.  This method is untried by this author.  As of now the “potential” exists only in my mind.]

3. A Really EZ Way
One of Loving Garland Green’s members, Cheryl Andres, suggested using the small chips of activated charcoal that can be purchased at an aquarium store.  [Be advised that 22 ounces of this stuff costs about $12 at most stores.]  You would need about 40 pounds of it for a 4’ x 8’ bed and this would cost you about $480 just for the charcoal.


Other Ways to Create and Not Create Bio Char

Chris advised us that it’s a tough job to make your own bio char by smashing briquettes.  According to Chris, it’s extremely messy and produces fine particulate dust that can harm your lungs.  He recommends soaking the briquettes in the compost tea, working them into the soil with a shovel, and then whacking them with the shovel.  Another member suggested using a rotor-tiller.

BE ADVISED:  Do not use “Quick Light” or “Easy Light” charcoal or the purpose of creating Terra Preta as it contains unwanted petroleum compounds.



Membership is free and we are open to the public.

We now meet the first and third Monday of each month at 216 East Kingsbridge Drive Garland Texas 75040.  Of course, be sure to stop and visit anytime you see us working in the Garland Community Garden at 4022 Naaman School Road.  We always have time to talk garden.

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