Farmer develops mussel shell fertiliser

Last updated 12:52 20/03/2014
Marlborough farmer Bill Brownlee, who has developed a mussel shell fertiliser, with the enormous mussel shell hill on his farm.

SHELL MOUNTAIN: Marlborough farmer Bill Brownlee, who has developed a mussel shell fertiliser, with the enormous mussel shell hill on his farm.

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The enormous pile of old mussel shells near Havelock could become a lot smaller because of the landowners' business venture turning it into fertiliser.

Bill Brownlee stores millions of shells from the Sanford mussel factory on his farm, on the Blenheim side of Havelock. He said the Marlborough District Council had estimated it as 13 metres high.

The pile started 50 years ago when his father took the shells, but had really grown in the past 15 years since mussel production boomed in the Sounds, he said.

He and wife Jane Brownlee bought a crusher from the Cape Campbell lime works and started a new venture, crushing the shells into a fine powder to be spread as fertiliser.

They had been selling it the past six months, Mrs Brownlee said, getting customers by word of mouth. Those customers ranged from people in Marlborough to people in Invercargill, Mr Brownlee said.

The shells could also be crushed to a grit for poultry, to give them calcium for their shells.

Their products used a waste product from one of Marlborough's industries, Mr Brownlee said, and kept a lot of material out of the council's landfill.

As the demand for the fertiliser grew, the pile would shrink, he said. However, he was in negotiations with the council to re-apply for a resource consent because the amount of shells was more than originally consented for.

They had tested the river and there was no effect on water quality from the piles, he said.

The shells were from greenshell mussels and pretty clean, so they tended not to smell.

It was rare for them to have meat still attached, but that didn't stop black-backed gulls hanging around in hope.

Blueshell mussels tend to have meat still in them and were considered "wet" and caused problems. Mr Brownlee said he had accepted them for a while, but no longer did.

He didn't know of anyone else using mussels shells to make fertiliser, but then, it hadn't been easy to develop the product, and there were few people with access to the volume of shells he had.

"It's not easy to crush. It's probably why people haven't persevered with it, I guess."

Hopai Bay farmer Kristen Gerard said the mussel shell fertiliser "completed a cycle" from harvested mussels, to fertiliser, and onto the land, and then eventually back into the sea for Sounds farmers.

About a fortnight ago, her family had ground spread 120 tonnes onto their flatter pastures, with a few minerals added for stock health. Another 60 tonnes would be aerially spread from a topdressing plane next month.

"Usually we source our lime from Murchison, or Clarence or even further afield, so it is good to have a closer source - cartage is a big part of our fertiliser bills."

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- The Marlborough Express

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