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This Australian Guy Wants Your Dirty Fish and Chips Oil

Tropiculture, a horticultural business in Australia’s Northern Territory, is paying local businesses for their used cooking oil and turning it into plant food.

While recycling used cooking grease isn't news to biofuel manufacturers or Chinese street vendors with a penchant for gutter oil, its use to fuel plant growth might be a first for the waste product. When deciding what might best benefit your rose garden, it wouldn't necessarily be instinctive to dump the dirty remnants of your mozzarella sticks into the soil. But one Australian man is essentially doing just that—with a few tweaks, of course.


Tropiculture, a horticultural business in Australia's Northern Territory, is paying local businesses for their used cooking oil and turning it into plant food. Owner Chris Nathanael can't technically market the product as fertilizer—due to it missing a certain percentage of nitrogen that would qualify it—but he claims that his Fish 'n' Chips for Plants basically does the same job. But hold up before you run off to dump the contents of your deep fryer into your garden, because the results aren't exactly replicable at home.

The idea to repurpose cooking oil as a garden aid first struck Chris 40 years ago, although he didn't get serious about the idea until nearly three decades later. Chris then spent 14 years trial-and-error testing his formula before settling on his final concoction. The current product is composed primarily of used vegetable oil, as well as smaller amounts of fish emulsion and molasses. Rich in carbon and other "secret" nutrients, Chris says the formula aids plant growth and protects against insects.

"The idea was that there was a lot of waste and no one seemed to be using it," he tells me. "We are recycling a tremendous product that would normally be dumped. We actually pay for all this—albeit very small [amounts]. We [tell] our supplier, 'We will pay you x number of dollars per 20-litre container.' That way we can guarantee they'll put it aside for us, and then we can go and pick it up."

The product went to market nine months ago, and has been sold predominantly to local commercial growers and a few eager green thumbs around the country. So far, it's been tested on vegetable plants, fruit trees, and lawns. "You will not believe the growth we got on tomatoes, it was unbelievable," Chris says, though he is also looking to expand testing to grain plants such as wheat.

While the idea of mixing fish and chip oil into farming soils sounds like an environmental nightmare, Chris assures me of the product's safety and says the environmental impact is virtually nonexistent. The product is diluted heavily before use for growers, using a maximum of 10 milliliters per litre of water for plants, and only at two to three week intervals. "There's no pollution at all because it binds with the soil," Chris says. "Because it's got detergent in it, it breaks down eventually and becomes part of the soil, part of the environment. It's very passive."

So while we all strive—at least in theory—to recycle, reduce, and reuse, it may be best putting that mindset to the test to use literal garbage to create growth. The food chain may no longer just be about what we eat; it's a more complex cycle of what we use to create that food, and how we can repurpose its by-products. Even if we don't want to drink a bucket of grease, our food just might.