What is Biochar? Stop by Greg’s stand every second Sunday at the market and find our how you can grow more from your soil using the 2,000 year old Aboriginal practice of ‘terra preta’. He also sells his beautiful honey which has a cult following.

Greg explains: ‘Biochar is any bio-mass heated in a limited oxygen environment, leaving a highly porous, carbon rich charcoal.’

Greg uses hardwood branches heated to about 700 degrees celsius. This produces a char which is highly porous with a high percentage of fixed carbon and makes my biochar especially good at retaining moisture in the soil, and sequestering carbon, because fixed carbon, as the name suggests, is extremely durable.

 Biochar also holds moisture within the soil. The spaces also provide habitat for soil microbes, making them more resilient to drought and able to rebound more rapidly when conditions improve. For this reason I recommend leaving chunks as they come rather than crushing the lot to powder.

The surface of the char attracts and holds a loose bond positively charged ions. These are many of the nutrients we add fertilizer for; phosphorus, potassium, magnesium, manganese etc. Biochar makes fertilizer more efficient and adding it is like adding lime to soil, raising the soil pH.

Biochar will also reduce the amount of non CO2 greenhouse emissions (CH4, N2O), and improve soil structure.

All in all it is a powerhouse of horticultural delights, but it doesn’t end there. Because of the inert aromatic structure of the carbon in biochar, it can  potentially remain in soil for thousands of years. The terra preta soils are over 2,000 years old and still going strong.