Circular economy program turns feral olives into vineyard biochar

By Melissa Keough

A group of wine industry environmentalists are turning feral olive trees removed from Fleurieu Peninsula national parks into a biochar product to boost the health of McLaren Vale vineyards.

The carbon recycling project is driven by local initiative Biodiversity McLaren Vale to clear problematic olive trees from Onkaparinga National Park and Glenthorne National Park – Ityamaiitpinna Yarta.

The olive trees are then burned at 500C in environmentally friendly machinery called a Tigercat.

Leading McLaren Vale viticulturalist and Biodiversity McLaren Vale co-founder Jock Harvey has been heavily involved in the project.

“We wanted a methodology that would work with biodiversity easier, be less time consuming and more effective,” said Harvey, a fifth-generation winemaker of Chalk Hill Wines and McLaren Vale Distillery.

“Once we removed the woody weed waste we weren’t just incinerating it into atmospheric gases, but we could use the biochar methodology to end up with a stable form of carbon that stays in the soil.”

Harvey said early biochar trials on local vineyards were showing promising signs of improved vine health.

“We have done three trials with the biochar and we are seeing that the vines are generally healthier. Healthier grapes will make better wine,” he said.

“Biochar retains nutrients and moisture … we are building resilience in the vineyard and we’re also reducing fire risk as olive trees are extremely flammable.”

The Department of Environment and Water, Biodiversity McLaren Vale and Peats Soil and Garden Supplies are among the organisations collaborating in the national parks project.

Peats Soil managing director Peter Wadewitz has dedicated almost 50 years to supplying compost, mulches and recycled organic resources to the horticulture and garden industries both locally and nationally.

Ten of those years have been spent experimenting with biochar.

“We have been playing around with it (biochar) for about 10 years, trying to learn and understand what a good and bad biochar is, going to workshops and being part of the ANZ Biochar Industry Group,” Wadewitz said.

Wadewitz introduced Biodiversity McLaren Vale to the portable Tigercat 6050 Carbonator, imported from the United States.

The large machine burns organic matter at 500C and reduces its volume by up to 95 per cent.

Wadewitz said there was great potential for commercialising biochar by inoculating or ‘charging’ it with compost.

The result is a valuable product that can then be sold to commercial partners including local vineyards, with potential also for fruit and vegetable crops.

“Somebody told me that biochar is like a big hotel that has been built without any occupants,” Wadewitz said.

“When you put the two (biochar and compost) together, it becomes this big happy party and the rooms are full of people.”

Wadewitz said the biggest challenge with biochar is the cost, with a high price point of around $1000 per tonne making it uneconomical for farmers.

“It’s got to provide some sort of return on investment for the farmer. So, it will be a case of supply and demand,” he said.

“There are many biochar plants that are not far from coming online. Once that happens the curve will soon come down.”

For now, the Biodiversity McLaren Vale group and Peats Soil’s goal is to continue working towards the creation of a circular economy.

“We are reducing the fire risk, as olive trees are a prolific feral weed species and extremely flammable,” Harvey said.

“It’s also increasing biodiversity and increasing the soil carbon. Australian soils are inherently low in carbon.

“Rather than just incinerate the olives, we can turn it into a stable form of carbon and sell it on the market.”

Picture: The portable Tigercat 6050 Carbonator used by Peats Soil & Garden Supplies to burn the feral olive trees. (Peats Soil & Garden Supplies.)

This article originally appeared at The Lead South Australia.

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