Worms turn grape waste to good use

Viticulturist James Dicey holds worm-made fertiliser, vermicast, at the Mt Difficulty vineyard in...
Viticulturist James Dicey holds worm-made fertiliser, vermicast, at the Mt Difficulty vineyard in Bannockburn. Photo by Jono Edwards.
A central Otago vineyard is embracing worms as the secret to turning wine by-product into fertilising "black gold''.

Mt Difficulty in Bannockburn this year bought 60kg of tiger worms to convert composted grape marc, made from grape seeds, skins and stalks, into vermicast, or worm poo.

Mt Difficulty viticulturist James Dicey said vermicast was filled with nutrients and known as "black gold''.

"Compost is good, but this stuff is like the Rolls-Royce of fertiliser.''

The vermicast would be used on its grape vines, he said.

"It's all about being sustainable with your waste streams.''

The vineyard set up lines of grape marc, and over the the past few months the worms turned 300 tonnes of it into 80 tonnes of vermicast.

The vineyard was now trying to retrieve the worms by attracting them using apple pulp and lime juice, so it could store them in another area with a smaller amount of compost to keep them fed over winter, he said.

"I don't know how many hundreds of thousands of worms we have now. They really breed like ... well, like worms.''

Central Wormworx co-owner Robbie Dick, who supplied the worms, said the vineyard was the only one he knew of in Central Otago turning its grape marc into vermicast.

He heard of another vineyard in Marlborough "making noise'' about using worms for this purpose a few years back, but did not know if it ever went through with it, he said.

"Grape marc is hard for worms to digest, due to its high potassium levels.''

For this reason, Mt Difficulty mixed the grape marc with molasses and horse manure.

Mr Dick said using worms was a sustainable way to convert waste into a "powerful'' natural fertiliser.

"Nobody can do it better than nature.''


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