DIY: biochar on a budget

Despite its potential benefits, biochar is generally too expensive for most farmers to buy. For this reason, Wihan Bekker, civil engineer at Ikhala Impact, explained to Glenneis Kriel how farmers can make their own.

- Glenneis Kriel

The idea of using biochar to enrich soil originates from the ancient practice of charring organic waste in the Amazon Basin, where it resulted in the rich, dark, fertile soil called terra preta.

Today, land in with terra preta in the Amazon sells for almost eight times more than the price of lesser farmland.

The use of biochar is seen as a valuable way of improving the soil and sequestrating carbon, according to Kelpie Wilson, owner of Wilson Biochar and author of The Biochar Handbook: A Practical Guide To Making and Using Bioactivated Charcoal.

BIOCHAR VS CHARCOAL

What makes biochar so special, and how does it differ from charcoal?

Wihan Bekker, civil engineer at Ikhala Impact, explains that charcoal is produced when organic material, such as wood and plant waste, is burnt at low temperatures (about 400°C), whereas biochar is produced at temperatures ranging from 600°C to 1 000°C.

The higher temperatures during biochar production result in a more complete combustion of volatile gases, as evidenced by the lower volumes of smoke produced, resulting in substantially lower carbon emissions compared with charcoal production.

Biochar production also shortens the time it takes to burn raw material. “Farmers who burn alien plants or pruned plant material typically wait days for all the material to burn in large piles, whereas we stop pyrolysis [thermal decomposition] after four to six hours when using a biochar kiln, saving all that carbon in the coals with water,” says Bekker.