BIOCHAR! What’s Old Is New Again
July 1, 2008
Population growth and the ensuing worldwide decline of resources are causing the cost of everything to spiral out of sight while the value of our properties plummets. Today’s “sticker shock” has become a catalyst for many to get serious about making lifestyle changes that will not only ease financial burdens, but will aid in slowing the rapid consumption of planetary resources. In this column I will present information on ways to do both. Growing up in a farming/ranching family and working in agriculture all my life will translate into a column dealing primarily with food production. But living sustainably covers much territory so I will occasionally veer from agriculture into topics such as; the positive economic benefits of supporting locally produced goods and services, alternative transportation, natural building, nutrition, energy and clothing issues.
This month’s topic is biochar, a term that recently came into usage to describe incorporating charcoal to greatly improve a soil’s biological activity. Biochar itself is ancient. I first came across terra preta (“black earth” to Brazilians) reading “1491” by Charles C. Mann, (I highly recommend the book). Mann conducted research on the North and South American continents prior to the arrival of Columbus and learned of a civilization, living along the Amazon 6,000 years ago and doing something so advanced scientists are still trying to understand it. Instead of slashing and burning the rain forest, as is done today to clear a plot of land for farming, this ancient culture turned the forest into charcoal then buried the charcoal along with their food scraps, excrement and pottery shards. Later generations grew crops in that medium for the next several thousand years without ever having to add any further amendments. Today, some of these soils, rediscovered in the first half of the 1900’s, have been intensively farmed since then, without additions to increase fertility. This is more astonishing when realizing that the typical crop lifespan of land that has been slashed and burned is only 2 to 3 years. In the Amazon most of the nutrient base is in the above ground biomass, slashing and burning it to ash consumes most of this base. What little nutrients are left are quickly used by farming and/or leached away by the intense rains. However, converting that biomass into charcoal only consumes about 50% of the biomass. When the remaining 50% - in the form of charcoal - is buried it will remain stable for thousands of years, perhaps even tens of thousands of years. The life span of this material is one of the many things scientists are trying to determine.
But that’s not the amazing part. Charcoal is incredibly porous and apparently there is something about the combination of this porosity (many things in soil are porous) and the charcoal itself that creates a fine habitat for the creation of countless beneficial microbes, which set up housekeeping in the charcoal converting crude organic matter into a nutrient-dense medium. Something else about charcoal as a substrate allows these nutrients to be doled out in an optimal way; very judiciously. Not even the intense rains of the Amazon leach them (or the intense watering of desert gardeners?). Plant roots, mycelium and other soil flora and fauna love this well aerated, carbon-based medium and flourish within it creating a veritable paradise of fertility.
But that’s not the amazing part. Burying charcoal sequesters CO2, our most problematic greenhouse gas. It’s a “net negative” sequestration as plants grown in biochar enriched soil grow faster and pull even more CO2 out of the atmosphere in the process of photosynthesis.
Even considering the smoke produced by making biochar, (50% of the biomass) it is still a “net negative.” When a crop of biochar is buried, its benefits will sequester far more C02 than was generated by its smoke. Plus, it will last far longer than the time it takes for the sequestered biomass to be replaced. If the next generation of biomass is turned into charcoal then a compounding effect begins. This compounding of sequestration is pretty amazing, but the most amazing aspect is that the gases (smoke) can be captured and converted into biofuels such as alcohol or diesel! We can have our cake and eat it too. Before the advent of electricity, our great-grandparents used kerosene as a lamp fuel. Kerosene was often distilled from the gases (smoke) created by the production of charcoal, which was used to fire wood burning stoves.
I spent several weeks in May making biochar in my outdoor earthen horno and applying it to my garden. It takes several years before the biochar becomes fully charged with nutrients, so I’ll be unable to report on the results for some time. If you are interested in using biochar you can buy lump charcoal, made from hardwoods and used for barbecuing. (Do not use charcoal briquettes, they’re often treated with starting fuel and fillers that you don’t want in your garden.) Biochar must be broken into 1/4” pieces to maximize the surface area. If you have a big garden this could be quite expensive as it needs to be applied at a rate of about 2% to 9% of the volume of soil. In other words if you roto-till 100 square feet to a depth of 8”, the math would be - lets say a 4% ratio - 4% of 8” x100 square feet. Cornell University, the leading institution in the U.S doing research into biochar, recommends starting with 2% and adding more later, if needed. There is no hard information on the optimal amount. As of my last check, the highest known ratio in the Amazon was 9%. My guess is that the amount will vary depending on the soil type, its pH and climatic conditions. Research is now being conducted to determine if biochar was used in other ancient civilizations in different ecosystems. If you’re interested in how to make your own biochar, contact me at katbambu@hotmail.com.
Because much of the world’s farmland has succumbed to erosion and loss of fertility due to poor farming practices, the implications for biochar are profound. The creation of what amounts to a permanently fertile soil, will change agriculture as we know it. The addition of chemical fertilizers to the soil will no longer be needed. Even current organic farming practices will become antiquated. For more information, Google biochar, terra preta or agrichar, or go to biocharInternational.org.
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