The Basics of Biochar

Biochar is simply charcoal that is used as a soil amendment to increase crop yields and conserve nutrients and water. But this simple material , first used thousands of years ago, has some amazing properties. Biochar can help you grow a better garden with healthier plants while using less fertilizer and less water. Biochar is also a stable, carbon-rich solid that remains in the soil for thousands of years – locking carbon away from the atmosphere.

Biochar-close-up

On a microscopic level biochar is extremely porous with a very high surface area. Like a tiny coral reef in your garden’s soil each small bit of biochar teams with life. Thousands of minute pores hold water and nutrients. Millions of beneficial organisms thrive and grow, breaking down soil, organic matter and themselves into vital plant nutrients.

Benefits of Biochar

  • Provides greater soil availability of nutrients
  • Improves plant resistance to foliar and soil-borne pathogens
  • Reduces leaching of valuable nutrients
  • Reduces irrigation and fertilizer requirements
  • Improves surface and ground water quality
  • Increases water retention in the soil
  • Increases the number of beneficial soil microbes
  • Reduces soil acidity
  • Increases the cation exchange capacity
  • Stimulates nitrogen fixation in legumes
  • Stores carbon in a long term
  • Improves soil structure

 

The History of Biochar

Biochar was used extensively by indigenous people in the Amazon basin more than 2000 years ago. Agricultural waste and vegetation was partially burned then smothered with soil in pits or trenches. When incorporated in the soil this mixture created islands of rich, fertile soil called terra preta de Indio by European settlers (literally “black earth” in Portuguese). These soils remain so fertile today that they are sometimes dug up and sold as potting soil in Brazil.

 

Biochar Production

Biochar is made by heating woody waste materials in the absence of oxygen, in a process called “pyrolysis.” The wood is not burned, but the process produces nearly pure carbon with millions of microscopic pores.

Biochar in hand

Biochar in Your Garden

Biochar is most effective when “pre-charged” before applying to your garden. If added directly to the soil biochar can temporarily hold back plant growth as nutrients are absorbed and populations of microorganisms stabilize.

Simply adding biochar to your compost bin will both prepare the “char” and improve your compost. For quicker use just mix biochar with aged compost, worm castings or compost tea and let it sit for 2-3 weeks. When pre-charged with beneficial organisms biochar becomes an extremely effective soil amendment promoting soil and plant health.