Waste not, want not
An Oxnard organic recycling company redoes soil enrichment, reduces greenhouse gases
By Shelby Maloney 04/19/2012
In the race against the clock to find new ways to fight climate change, Agromin, an Oxnard-based organic recycling company, plans to aid in the effort to modernize an ancient soil enhancement technology by developing its own version of a charcoal-like soil amendment known as biochar. Biochar is produced from organic biomass, or plant waste, and is known to have several environmental benefits, including carbon sequestration, the act of taking carbon out of the atmosphere.
“We’re beginning some plant trials,” said Robert Lerner, the manager of biochar business development at Agromin. “Biochar is really … a natural for [Agromin] because the same feed stocks they use from making compost can also be used for making biochar.” Agromin expects biochar production systems to be operational at two of their facilities within the year.
The origin of the biochar soil enrichment technique lies in the dark earth soils of ancient Amazonia, otherwise known as terra preta soils. Terra preta soils contain charcoal, fish bones, ceramics and other bits of debris. They are highly fertile and have remained so for thousands of years. “Basically, the whole biochar concept is to try to emulate this ancient agricultural wisdom of using charcoal and organic matter as additives to our soil,” said Lerner.
Currently, biochar is made in a pyrolysis process whereby organic waste is heated in the absence of oxygen. Thermal degradation breaks down the biomass, and a combustible gas is produced. The produced gas is then used to promote the biochar production process, leaving behind a charcoal residue. “Charcoal is generally a fuel for cooking. If we take the same material and crush it and put it in the soil, we call it biochar,” said Lerner. Unlike charcoal that would be fit for cooking, biochar can be made out of any organic waste product.
Decomposition of plant waste typically returns the carbon dioxide retained by the plant in photosynthesis to the atmosphere. “If we stabilize it in charcoal, it stays in the soil,” said Lerner. “The big deal is that the charcoal is stable in the soil, so it can last hundreds of thousands of years.”
In addition to carbon dioxide, agricultural fields also have significant emissions of other greenhouse gases, including nitrous oxide and methane. According to Lerner, fields that have been treated with biochar produce roughly half of these gases.
Though the biochar production process requires an initial supply of heat, it produces more than enough energy than is needed to sustain the reaction. Phoenix Energy, a biomass-fueled power plant in Merced, currently produces biochar as a waste product of making energy.
According to Lerner, reduction of greenhouse gases isn’t the only benefit to using biochar. “You get a big boost in beneficial soil microorganisms,” said Lerner. “The mineral nutrients so important to plant nutrition don’t get leached out with water but rather stay in the rhizosphere, the plant root zone, and you get better moisture retention.”
Lerner explained that biochar in soil has a weak electric charge and can essentially act as a magnet to plant nutrients, which are mostly ions with a positive charge. “In very extreme habitats, like in the tropics, for example, or in desert areas, the addition of the charcoal makes it possible to get a big boost in plant yields,” said Lerner. “In our area here, we can look forward to significantly reducing irrigation requirements and, most of all, the addition of petrochemicals.”
While the basic framework of the biochar technology has been laid out by the ancient Amazonians, Lerner explained that it isn’t just as simple as adding straight charcoal to the soil and expecting to get the same enhancement results.“We’re doing a lot of product development and working with our growers on experimenting with how much biochar to add and it’s effects,” said Lerner.“It’s possible that if you take straight charcoal and put it in the soil … you might actually be robbing the plants of nutrients they might otherwise have.”
In a 2010 study, it was calculated that if industrial-scale biochar production was practiced globally, it could offset carbon dioxide emissions by 12 percent. “If we reshape the way we do agriculture around the world to take a portion of the waste, a portion of, say, the trimmings of lumber mills or things that are currently burned in big piles, and divert it into biochar production … we could make a significant contribution to our effort to reduce greenhouse gas production,” said Lerner. “This is a new science and we’re all very excited.”