Biochar is the lightweight black residue, made of carbon and ashes, remaining after the pyrolysis of biomass, and is a form of charcoal. Biochar is defined by the International Biochar Initiative as “the solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment”. Biochar is a stable solid that is rich in pyrogenic carbon and can endure in soil for thousands of years. (Wikipedia)
The concept of biochar is rooted in an ancient Amazonian practice
Although biochar technology is considered a more recent strategy for carbon sequestration, the practice of adding charred biomass to improve soil quality is not new. This process is modeled after a 2,000-year-old practice in the Amazonian basin, where indigenous people created areas of rich, fertile soils called terra preta (meaning “dark earth”).
Whether these soils were intentionally made or are simply a by-product of farming and/or cooking practices is still unclear. But one thing’s for sure: The fertility of terra preta is significantly higher than the otherwise famously infertile soils of the Amazon. This explains why plants grown in terra preta soil grow faster, and are more nutrient-dense, than plants grown in neighboring soils. In fact, terra preta soils continue to hold carbon still today. (source Regeneration International)
Why use Biochar in Agriculture / Garden
Soil degradation is a major concern in agriculture world wide. Applying biochar to degraded soils in order to enhance its quality . Some of the ways that biochar may help improve soil quality include:
- Improving soil structure
- increasing water retention and aggregation
- has a very low pH, so it is highly beneficial in alkaline, coastal sandy soil to lower pH
- improving porosity or void (this is a measure of the void (i.e. “empty”) spaces in a material)
- regulating nitrogen leaching
- improving microbial properties
Biochar is also found to be beneficial for composting, since it reduces greenhouse gas emissions and prevents the loss of nutrients in the compost material. It also promotes microbial activity, which in turn accelerates the composting process. Plus, it helps reduce the compost’s ammonia losses, bulk density and odor.