We tested five different at-home food waste methods and dish the dirt on compost and worm farm systems.
Composting your food waste is a win for the environment. Our trial of five methods, from a machine for your kitchen bench to outdoor worm farms, found you don’t have to pay top dollar to hit pay dirt.
If you’re keen to divert your food waste, here’s our advice:
Ten Consumer staff members trialled a composting method they’d never used before. Some had a compost bin or worm farm up and running, although others were complete newbies. They tested and rated the systems from June to August – though our Food Cycler triallists had the machine for a maximum of a month each.
We didn’t test the effectiveness of the compost, as that depends on what went into each system.
The method: Food scraps, cooked foods, fresh lawn clippings and wilted flowers go into an airtight bucket, alongside a layer of powder or spray, which contains microbes that ferment the waste. Once the bucket is full, it’s left for two weeks (longer in cold weather), so you may require two sets. After that, the solids can be added to your regular compost pile or dug into the garden. Liquids can be poured down the sink or diluted and used as plant fertiliser.
Pros: Unlike regular compost bins, bread, cheese, meat and seafood can go into bokashi buckets. The systems don’t take paper or cardboard.
Cons: It’s a multi-step process. Microbe powder or spray must be regularly purchased. The two bokashi systems we trialled returned mixed results.
$74.98 from Mitre 10 (includes bokashi powder, $15.29 for 1kg)
$39.90 from Bunnings (includes bokashi spray, $12.98 for 500ml)
The method: Fruit and veges, eggshells, coffee, tea, paper, lawn clippings, leaves and twigs are added to a spinning bin on legs. As the composting process speeds up if contents are regularly turned and aerated, a tumbling bin makes this easier. Once broken down, the compost can be used on or dug into the garden.
Pros: Compost is produced more quickly than in a standard bin. Raised from the ground, the material may attract fewer pests.
Cons: The bins can’t handle large amounts of dairy, meat, oils and seafood. Only one of the bins we tested received a thumbs up.
$169.00 from Mitre 10
$279.00 from Bunnings
The method: Fruit and veges (with a few caveats), cooked food (ditto), egg shells, coffee, tea, paper, lawn clippings, leaves and twigs are fed to a bin of tiger, red and/or Indian blue worms, which eat the material and produce worm castings. This “vermicompost” falls to the bottom of the bin. Once harvested, it can be either mixed with soil and sprinkled on plants or dug into the garden. Liquids can be diluted and used as plant fertiliser.
Pros: Worms can produce finished garden material faster than a compost bin. Aeration isn’t required. The two worm farms trialled received the nod.
Cons: Worms aren’t as hardy as soil microbes. They’re also fussier eaters: disliking acidic, fatty and spicy foods as well as bread, dairy, meat, oils and seafood. A worm farm can’t be left unfed for long periods.
$99.00 from Mitre 10 (plus $50.00 for 500g live worms)
$325.00 from Hungrybin.co.nz (plus $50.00 for 500g live worms)
The method: Food waste is collected by a commercial composter courtesy of a bin left on the kerb once a week. The company creates and sells (or uses) the final compost. The commercial services are in their infancy and aren’t available everywhere.
Pros: It’s low maintenance. Both services tested won rave reviews from our volunteers.
Cons: The costs are ongoing. KaiCycle doesn’t accept eggs, meat, oils or seafood and, while planning to expand, is fully subscribed.
$34.50 per month
$46.00 per month
The method: The Food Cycler comes with a bucket, into which food waste (with some exceptions) is added. The machine runs a three- to six-hour cycle in which the scraps are heated and shredded. It’s recommended that the leftover dehydrated material is then sprinkled on your garden.
Pros: Food Cycler accepts bones, fruit pits and meat. The system works indoors.
Cons: Considering the price, the machine has a long list of no-nos: large amounts of banana, bread, cake, citrus peel, cherry, dressing, grape, jam, melon, nut butter, orange, rice and sauce. Of the five, it’s the only system requiring electricity and producing noise, which put off our triallists.
$650.00 from Snapfoodwaste.co.nz (includes filters, normally $75.00)
Electricity consumption: We measured the Food Cycler’s power usage during three cycles. Based on costs of 27¢ per kilowatt hour, the machine averaged 14¢ per cycle – about half that consumed by a new dishwasher per load. If you ran it every day (as our volunteers estimated they would), that’s roughly $49 a year.
The New Zealand supplier, SnapFoodWaste, said the machine, when running, “uses less than one kilowatt hour” (27¢) or 0.07 kilowatt hours (2¢) per day on standby.
GUIDE COST excludes delivery. RATINGS based on surveys completed by the triallist testing the product. Two triallists tested the same Food Cycler.
The bacteria Legionella occurs naturally in soil, potting mix and compost. The microbe can be inhaled, causing a lung condition with symptoms similar to pneumonia, including aches, coughing, fever and shortness of breath. If untreated, an infection can develop into Legionnaires’ disease, which can be deadly.
When working with compost or worm casts, wear gloves and wash your hands thoroughly afterwards. You can also wet any material to reduce airborne particles.
Rodents are another unwanted presence in compost piles. Securing wire mesh to the bottom of standard compost bins prevents them burrowing in, but still allows soil microbes and worms to do their thing. There’s a rodent-proofing guide on Predator Free Wellington’s website pwf.org.nz.
If you send food scraps to the dump, chances are they’ll end up getting buried. Without air, organic waste decomposes and produces methane, a greenhouse gas that traps more heat than carbon dioxide.
As long as it’s regularly aerated, the material in your compost will produce comparatively less methane and other greenhouse gases. Research indicates the same is true for worm farms.
If you’re a home composter, you’ll also prevent emissions created by transporting food waste to the tip. Studies suggest compost systems can transfer the carbon from organic waste back into the soil (a process known as “sequestration”), but this is dependent on conditions.
The harvested compost products, solid or liquid, help your garden thrive by adding oxygen and nutrients. Some final material is so potent it must be diluted before it goes on plants, topsoil and vege gardens. To be sure, read your system’s manual.