Seaweed Bio-stimulant

The seaweed man Alex Pressman.

Interview for RNZ

Alex Pressman is turning an invasive marine pest into a business. His company, Waikaitu, takes wakame (Undaria pinnatifida) and turns it into fertiliser, food and even bee tucker. This Fast-growing seaweed was introduced to New Zealand waters in the 1980s via ballast water from cargo ships. The seaweed had soon became a problem, choking out native species and fouling chains in mussel farms.

“When I started doing the research into what should be done with this species I found something fascinating. The seaweed’s name is undaria pinnatifida - it’s known everywhere in the world as wakame, probably one of the most used seaweeds for food in the world.

“It’s the green stuff that floats in miso soup.” In Japan they use 200,000 tonnes of this seaweed every year and most of it is imported from China and from Korea.

Alex Pressman believes wakame has a far greater value to New Zealand as a fertiliser.

“Our agricultural sector is a very factory-based concept, very chemistry focused and this chemistry is wreaking havoc with our soil; pesticides, herbicides and nitrogen and phosphorous fertilisers damage the soil biology.”

Seaweed-derived fertilisers could be the answer, he says.

He says seaweed fertilisers reduce the amount of nitrogen used, stabilise the nitrogen that’s already in the soil and have been seen to reduce powdery mildew in some common crops.

And he says with a world population set to reach 9 billion, we going to have to ramp up food production without further polluting our fresh water and soil.

“In the next 40 years we’re going to have to grow as much food as we did since the dawn of farming 10,000 years ago.”

listen to the full interview

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Jun 7, 2018, 12:00 PM