What is Biochar?
Biochar is a charcoal-like substance that’s made by burning organic material from agricultural and forestry wastes (also called biomass) in a controlled process called pyrolysis. Although it looks a lot like common charcoal, biochar is produced using a specific process to reduce contamination and safely store carbon. During pyrolysis organic materials, such as wood chips, leaf litter or dead plants, are burned in a container with very little oxygen. As the materials burn, they release little to no contaminating fumes. During the pyrolysis process, the organic material is converted into biochar, a stable form of carbon that can’t easily escape into the atmosphere. The energy or heat created during pyrolysis can be captured and used as a form of clean energy. Biochar is by far more efficient at converting carbon into a stable form and is cleaner than other forms of charcoal.
In terms of physical attributes, biochar is black, highly porous, lightweight, fine-grained and has a large surface area. Approximately 70 percent of its composition is carbon. The remaining percentage consists of nitrogen, hydrogen and oxygen among other elements. Biochar’s chemical composition varies depending on the feedstocks used to make it and methods used to heat it.
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.
Biochar can be manufactured through low-cost, small-scale production using modified stoves or kilns, or through large-scale, cost-intensive production, which utilizes larger pyrolysis plants and higher amounts of feedstocks. One of the most common ways to make biochar for on-farm use is through pyrolysis using a top-lit updraft biochar machine.
Applications of biochar in agriculture: enhancing soil and compost properties
Soil degradation is a major concern in agriculture globally. To address this burgeoning problem, researchers suggested applying biochar to degraded soils in order to enhance its quality. Some of the ways that biochar may help improve soil quality include:
- enhancing soil structure
- increasing water retention and aggregation
- decreasing acidity
- reducing nitrous oxide emissions
- improving porosity
- regulating nitrogen leaching
- improving electrical conductivity
- 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.