By TERRI ADAMS, The Prairie StarThursday, May 6, 2010 6:10 PM MDT
Biochar is a new buzz word in agriculture but, exactly, what is biochar?
Biochar is a soil amendment made by converting manure, crop residue and other bio-waste materials, including sawdust, into charcoal by using pyrolysis, which is heat without oxygen.
“It is made in the exact same way as charcoal. You heat the material above a certain temperature without letting any oxygen in,” said Catherine (Catie) Brewer, a PhD student in chemistry and graduate research assistant at Iowa State Univer-sity. “This is different from burning or combustion in which you add oxygen. Without oxygen you get biochar.”
Biochars are attracting a lot of interest for both commercial and agricultural applications, and for small scale use. According to Brewer, chars have shown the ability to increase soil fertility, im-prove water retention, lower soil acidity and density, and increase microbial activity.
Biochars also help with the carbon level of the soil.
While some forms of carbon, like carbon dioxide, carbon monoxide, carbon particulates, are harmful to humans and animals when in the atmosphere, carbon is very beneficial in the soil.
It acts as a home to beneficial microorganisms and as a sponge to hold nutrients where plants can use them, resulting in higher plant yields with lower input costs.
Biochars also help the soil hold just the right amount of water, retaining water during periods of drought and improving drainage during wet seasons which helps reduce flooding, mudslides and other problems associated with excess moisture.
The longer the carbon can remain in the soil, the longer the soil and plants can benefit from its presence.
Brewer explained that all bio-matter has two types of carbon in it - a carbon that is immediately available and decomposes quickly and a more stable carbon that breaks down in the soil over a long time.
The majority of biomass releases its carbon quickly and the benefits rapidly deplete.
For example, corn stover left in the field one year disappears within a few years. In biochar the majority of the available carbon is the more stable, slowly decomposing variety that can benefit the soil of years.
“Producers would put biochar on one part of their field and then not have to reapply it again for a couple of decades,” said Brewer.
Decades? Decades, affirmed Brewer. “If you make the char right and if you apply it in accurate quantities the first time,” she said. Brewer said researchers can see the effects of char in the soil for hundreds, even thousands of years. Some of the richest, blackest soils in the world are loaded with biochar materials that have been in the soil for centuries.
“Some producers are worried about tilling bichoar in because they use no-till or reduced-till methods; but with biochar they may only have to add it once with a lasting benefit,” she said.
Brewer explained how the biochar process might work for producers. After harvest, a corn producer would gather all the stover off his field and take it to a pyrolysis facility that can heat the biomass to the proper temperature without oxygen. After the farmer offloads his stover, he would then drive around to the back of the factory and pick up a load of char, take it back to his farm and spread it on his fields for long-term fertilization benefits.
Biochar is not the only usable product of pyrolysis. “Whenever you burn something you get three byproducts,” explained Brewer, a gas, a charred solid, and a liquid. Relating it to cooking, Brewer said that when you burn something on the stove or in the oven there is a release of gas from the product, charred remains left behind, and a sticky, oily residue or tar.
In Brewer's research group they are focusing on processes that favor the liquid product, known as bio-oil. This bio-oil can be collected and upgraded so that it can be shipped for processing in existing refineries.
Even the gas from the pyrolosis process can be captured and used to produce heat or electricity, said Brewer. The different products and the amounts would vary by the biomass used and the method. It could be tailored to fit different needs. For agriculture producers, it would be a way of turning their bio-wastes, from crop resi-due to manure, into valuable, long-acting fertilizers, improve the soil on their land, and increase their yields.
Currently the biochar industry is small and limited to small facilities, but it is growing.
“We have a chicken before the egg problem when it comes to larger-scale implementation,” Brewer said. While big industry might be interested in building biochar facilities, they want to make sure they will have a market for the char. That market will grow as research continues to test its viability and validity in small research plots.
Already there are some companies looking at producing small biochar facilities that can be used in backyards or moved from field to field in the agriculture sector.
“You could make char yourself at home, in 55-gallon metal drum. You just start a fire and when it gets going you put the lid on the drum and let it burn without oxygen,” she said. Making char that way is very inefficient and provides low yields. “It's also dirty in regards to air pollution.”
Brewer stated that there are other, more efficient ways, and the more efficient the method the cleaner the output. She would eventually like to see co-op-sized facilities used by several farmers or small communities for the benefit of the community.
She said that they are even developing small biochar stoves that would use biomass as a fuel and produce char for returning back into gardens and yards.
Developing countries are especially in-terested in the stove aspect.
For more information, check out the International Biochar Initiative's Web site at www.biochar-international.org
Posts
No comments:
Post a Comment