This article originally appeared in Garden Culture Magazine US21 under the title, “Biochar”.
What if there was a natural soil conditioner that was not only easy to source but could feed soil microbiology and remain stable for thousands of years? Well, read on! Biochar has the most complex structure of any material on Earth and is excellent for improving soil retention while also protecting against soil-borne diseases.
What Is Biochar?
The name “biochar” stems from a combination of biomass and charcoal. The product is the result of a process called pyrolysis, a procedure that involves heating wood to a temperature of 250°C or more in an oxygen-deprived setting.
The science behind this involves carbon being absorbed from a gas into a solid state. The commercial by-product is known as charcoal. At a microscopic level, the structure of this clean, chemical-free, highly stable carbon material has more surface area than an entire football field once unfolded and flattened. The intricate design of charcoal is easily the most compact and porous material on this planet, with carbon dating proving that the Earth has been amending itself with naturally-formed biochar for millions of years.
A Greek word meaning “fire” and “separating”, pyrolysis is an irreversible change in chemical composition. By heating wood to temperatures of 250-300°C, organic matter is suppressed into a carbon-rich substrate.
The difference between ash and biochar is the amount of oxygen present at the time of combustion. Because biochar is made in an oxygen-deprived setting, the substrate will not turn to ash.
A Complex Structure
Larger surface area leads to higher water retention, improved drainage and an increase in wicking action in the event of rainfall. The way biochar is formed ensures it will not decompose; its resistance to chemical and biological weathering helps it endure the elements for thousands of years, and during that time, biochar acts as a buffering agent for micro and macronutrients.
Used by green-conscious farmers to fight climate change, adding biochar in small broken pieces serves as the ultimate amendment, increasing soil fertility, nutrient-uptake and the general condition of farming lands.
Food For Thought
The microbiology deep within the soil culture plays a huge role in the uptake of nutrients for plants. Soil microbiology can determine what minerals and nutrients are fixed into the Earth. For example, depletion of nitrogen can be amended by nitrogen-fixing bacteria, or by carefully balancing phosphorus levels. The beneficial bacteria that live in the soil thrive in oxygen and carbon-rich environments.
As the charcoal breaks down over time, tiny pieces will replenish the depleted soil. Biochar can be mixed into soil as a growing medium, which improves aeration and water retention, while also slowly releasing nutrients over time. For large-scale farming, adding a top layer of fine charcoal dust will enrich the soil during rainfall.
What Are The Benefits Of Using Biochar?
There are numerous benefits to using biochar; not only is it environmentally friendly, but it is also cost-effective. Users reduce their carbon footprint by producing a soil amendment that classifies as “all-natural”. Biochar has the ability to retain water and also encourages the wicking action of the soil; meanwhile, the composition of the nutrients available to the plant roots will improve. Once biochar is made, it will be readily available for at least a thousand years.
Rainfall triggers the biochar to slowly leach nutrients into the soil, instead of washing them out and pushing them below the surface where roots may not be able to access them. Using biochar in your soil will improve plant vitality, vigor, growth, and increase silica uptake. While boosting the soil microbiology dramatically, expect to also gain added protection from soil-borne diseases, as well as an increase in plant metabolism.