Regional business hoping to open eyes of wine producers to sustainable use of discarded grape marc

A regional business is hoping to open the eyes of wine producers in the South West to the sustainable use of wasted skins, seeds and stems of grapevines.

The materials created in the production of wine, known as grape marc, currently end up rotting in a pile or are shipped off to landfill once the chardonnays and shirazes have been bottled up to drink.

However, organic recycling business C-Wise chief executive Greg Watts said the wine industry had been turning a blind eye to the massive environmental impact of grape marc.

“Australia crushes around 1.5 million tonnes of wine grapes per year, almost 37,000 tonnes coming from WA,” he said.

“There’s a huge amount of waste in that figure that can deliver economic and environmental benefits.

“Just because it’s leftover doesn’t mean it’s waste.”

Mr Watts’ solution for the skins of grapes long since fermented is simple — compost.

He said converting grape marc into compost would help solve solve one of the biggest problem vineyards face.

According to Wine Australia’s 2023 Emission Reduction Roadmap, the Australian wine industry was responsible for 1,770,977 tonnes of carbon dioxide emissions in 2020-2021.

While transport supply chains equated to well over half of these total emissions, about 10 per cent came directly from the vineyards.

Crop residue and soil emissions were calculated to contribute around 290,000 tonnes of carbon dioxide.

Mr Watts said the larger players in the wine industry garnered attention for their sustainability efforts but it was the smaller wineries with tighter margins and limited resources which had the most to gain from sustainable practices.

“Adopting more sophisticated composting practices, wineries can achieve significant cost savings through improved yields, reduced reliance on fertiliser inputs and better vine and wine quality,” he said.

“Ignoring this opportunity means missing out on a simple method to both reduce waste, improve soil quality and avoid the cost burden of fertilisers and insecticides.”

Mr Watts said once the process was fine-tuned, the benefits would include boosted soil moisture retention, improved soil structure, sequestering carbon and reduced fertiliser dependence.

“Soil biology prefers a certain ratio of carbon to nitrogen and this ratio of organic materials is important when making compost,” he said.

“If the ratio is too high in carbon, microbes can lack sufficient nitrogen, leading to slower decomposition and reduced nutrient release and this all plays into the quality of vines and wines.

“By blending grape marc and other organic waste into nutrient-rich compost, wineries can significantly reduce their environmental impact and create a beneficial resource for their vineyards.

“There’s nothing more valuable than returning to the land what you’ve taken from it.”