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BIOCHAR, THE NEW BLACK GOLD FOR SOIL

written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

Have you heard about biochar? While some scientists are calling biochar the new ‘black gold, ‘ it’s probably not on most gardeners’ radar. The technical definition of biochar according to WSU researchers is that biochar ‘is a carbonaceous product made from the pyrolysis of organic materials (usually lignocellulosic, or woody, materials).’ They explain that it’s basically a charcoal material that’s being studied for its potential benefits when added to soil.

Studies of the black earth soils (known as terra petra) in the Amazon have revealed a high biochar-like content. The reason biochar is being studied is because it’s believed the high productivity of the Amazonian black earth soils are due to the biochar they contain.

However, scientists aren’t just interested in biochar’s potential ability to improve soil fertility and crop production. They’re also interested in other possible environmental benefits related to creating and adding biochar to soils. In the Amazon the soil biochar has stored carbon for over a thousand years. The scientists at WSU and other universities want to know if the same will apply in Washington soils and other regions. Sequestering carbon in our soils would be help slow the increase of human-caused greenhouse gas emissions. An additional benefit of biochar could be realized if it’s processed and made into activated charcoal for use in water purification.

It’s believed that the biochar in Amazonian soils was created by human agricultural activities, especially the burning of vegetation. Biochar is the result of burning, or pyrolysis as the scientists call it. Pyrolysis is defined as a ‘thermochemical conversion process for biomass materials.’ This simply means that heat is used to break chemical bonds. The heat is applied under low oxygen conditions to keep the material from burning up. Pyrolysis has been used for thousands of years to make charcoal.

Is biochar simply charcoal? No, charcoal is made using low-tech ‘slow pyrolysis.’ Biochar can be made using modern slow, fast, or flash pyrolysis processes. When materials are processed using pyrolysis, there are three products. The solid portion is biochar, but there are also both gaseous and liquid co-products. The liquid portion can be turned into a ‘green fuel’ or bio-oil and the gaseous portion (syngas) can be burned for energy production.

So what types of materials can be used to produce biochar? Almost any organic material can be used but the best candidates are low in moisture content, low in proteins, and high in lignins and cellulose. Scientists are focusing efforts on utilizing farm and forest waste products, materials such as crop residues, nut shells, wood prunings from orchards and vineyards, sawdust, wood chips, manure, grasses, and sewage sludge.

Why would gardeners be interested in someday being able to add biochar to their garden soil? I’ve already noted that better plant growth and yield is attributed to soils high in biochar, but scientists believe it may help reduce fertilizer requirements, reduce leaching of nutrients from the soil, improve soil texture and structure, improve water movement in the soil, and increase beneficial soil microbes.

Biochar isn’t available yet for home gardeners to try, but perhaps it will be in a few years. Right now scientists are researching’Black Gold’s’ total potential for reusing agricultural waste, improving the environment, producing green energy, and improving agricultural soils.

SIDEBAR:

Biochar is just one of the topics that is being presented by WSU faculty, USDA scientists, and Northwest experts at the 2012 Master Gardener Advanced‑Education Conference being held at the TRAC in Pasco on September 13 through 15. What’s exciting is that the conference is open to the public, as well as to Master Gardeners from around the state. Dr. Harold P Collins, USDA microbiologist, will be presenting a class on ‘BIOCHAR – Agriculture’s Black Gold? The Promise of Biochar’ at the conference.

Other exciting classes for gardeners include: Grafting Vegetables; Bat Ecology; Columbia Basin Ecology and Flora; Growing Backyard Blueberries; Growing Grapes for the Table, the Bottle, and the Arbor; The History and Future of the Potato; Drip Irrigation for the Yard and Garden; Straw Bale Gardening; Pollinator Ecology; Vegetable Gardens: An Edible History; and more. Natural history buffs are sure to like ‘MCBONES

Coyote Canyon Mammoth Dig’ and ‘Transforming the Landscape and Soils of the Inland Northwest: the Ice Age Missoula Floods.’ To learn more about the conference and to register on-line go to http://mastergardener.wsu.edu/mgfws/advtraining.htm

Published: 8/10/2012 1:49 PM

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