If you missed those, biochar is defined simply as “charcoal that is used for agricultural purposes.”1 It is created by the pyrolysis of biomass – in other words, basically “cooking” wood in the absence of oxygen. The really neat thing is that once the pyrolysis reaction has begun, it is self-sustaining, requiring no extra outside energy input. In addition, there are other useful byproducts of the process including minor quantities of methane (CH4), tars, organic acids and excess heat.1
“Making charcoal may sound like a strange way to boost crop production, but the concept was proven more than 2,000 years ago in South America, where native farmers added charcoal to the poor soils of the Amazon rainforest to create a rich, fertile soil known by the Portuguese name ‘terra preta,’ or black earth.”2
A simple Google search of this will yield you lots of very interesting articles. Furthermore, and probably the key reason biochar is making a comeback, is that it effectively locks up carbon from the atmosphere. In other words, biochar is able “to reduce emissions from biomass that would otherwise naturally degrade to greenhouse gases,”3 so it therefore has “appreciable carbon sequestration value. These properties are measurable and verifiable in a characterization scheme, or in a carbon emission offset protocol.”3
However, getting to the fertilizer theme of this issue of Greenhouse Canada, biochar has been found to have a number of other benefits, including:
- Reduced leaching of nitrogen into ground water.
- Increased cation-exchange capacity, resulting in improved soil fertility.
- Moderating of soil acidity.
- Increased water retention.
- Increased number of beneficial soil microbes.3
McCandless and his colleagues at Glorious Organics have been making their own biochar for a couple of seasons now, and have been working with grad students at UBC and Simon Fraser University to evaluate potential uses and benefits in a real-world organic farming situation.
Biochar can improve almost any type of soil, but it is especially effective on nutrient-poor and free-draining soils in low rainfall areas because it helps soil retain moisture and more of the nutrients that are put into it. In other words, biochar can help you as a grower to be more effective in your use of fertilizers: you can save money. Furthermore, retaining these nutrients in the soil profile, and therefore having more available to plants, means there is less leaching into the ground water: less pollution.
Sounds good so far. But there is more. In addition to being a soil enhancer, “sustainable biochar practices can produce oil and gas byproducts that can be used as fuel, providing clean, renewable energy. When the biochar is buried in the ground as a soil enhancer, the system can become ‘carbon negative.’”3
But hang on a minute, a word of caution. A number of studies have shown these results are not always achievable. Some studies “have shown no difference, or even some decline, in productivity. The reason lies in the wide range of properties between different biochars, and variation in impact due to interaction with different soil types.”5 Which is why Glorious Organics is working on a biochar for its specific farming situation.
Whether you’re a climate change skeptic or not, biochar has many promising benefits including reducing your fertilizer use. So like Glorious, you might want to check it out for your situation. Perhaps you should even make your own, especially if you can figure out a way to turn your new biomass boiler into a pyrolysis burner. That could be really cool!
- Biochar Info, accessed at http://www.biochar.info/biochar.biochar-overview.cfml, Aug. 18, 2012.
- Rice University, in Greenhouse Canada, March 2012, accessed Aug. 21, 2012, at http://www.greenhousecanada.com/content/view/3132/131.
- International Biochar Initiative, at: http://www.biochar-international.org/biochar/ Aug. 18, 2012.
- Australia and New Zealand Biochar Researchers Network, accessed at: http://www.anzbiochar.org/biocharbasics.html#six, Aug. 21, 2012.