Convenient community composting
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Frequently asked questions

How it all works:

What can I put in my bucket?

Thanks to the high temperatures and rat-proof design of our NZ Box composting bins, we can compost most of your kitchen scraps, including things that you wouldn’t compost at home. Check out our Soil Ingredients List.

What does Soil Factory cost?

We have different rates for households and businesses, and it depends on how much food waste you have, and whether it’s a collection or drop-off service - check out our rates here, or get in touch if you’d like us to provide a quote for your needs.

I don’t know how many buckets I need, is this a problem?

Nope. You can always add more buckets if you need, or return some if you don’t need them, and we’ll adjust your rate accordingly. For businesses, we’re happy to provide you with buckets to help you audit your waste before you sign up.

How do you compost our scraps?

We use the NZ Box hot composting system, designed in Auckland for the purpose of community-scale composting. Food scraps are mixed with other organic waste products and by-products that we source from local businesses, including woodchip, wood shavings, sawdust, coffee chaff, coffee grounds, grass clippings, cardboard and more. If you are looking to dispose of any of these materials, or similar dry compostable materials, feel free to get in touch.

What happens to the finished compost?

The finished compost is returned to the soil at Kelmarna, adding fertility and structure to our vegetable beds, and helping us to grow more local, organic food, and run our educational and therapeutic programmes.

In future, if we produce a surplus of compost we will look to make it available to our members and the public.

Can I line my bucket with something to make it easier to wash out?

You are welcome to line your bucket with newspaper, or alternatively use a certified compostable bin liner, which must be certified to Australian Standard AS4736-2006 or European Standard EN13432-2000. If you’re unsure which compostable liners you can use, please ask us first!

What is bokashi?

Bokashi composting is an anaerobic process that relies on the addition of material inoculated with beneficial microbes to ferment kitchen waste. The compaction and fermentation of the material means that you don’t need to empty your bin as often, and the material that you provide us with is already partially processed.

You can find out more about bokashi on the Compost Collective site, or by attending one of their free composting workshops around Auckland, where you can also receive a discount off the purchase of a bokashi system.

Where do you collect?

Our collection area covers parts of Ponsonby, Herne Bay and Grey Lynn. Check out our map to see if you’re in the zone.

When do you collect?

Every Friday, between 9am and 3pm.

When can I drop off my bucket?

Drop-off days are Wednesday to Friday. During the Kelmarna shop hours (10am - 4pm), you can find us in the shop (and also buy organic produce grown using the compost we make together)! Out of hours, you can drop your scraps off on Wednesday or Thursday evenings using our after-hours bin.

Do I have to drop off my bucket every week?

Yes, even if your bucket isn’t totally full, you’ll need to bring it in to empty every week. Food scraps kept for more than a week are likely to start to putrefy - which means slimy, smelly food that is bad news for everyone.


Why we're doing this:

What happens to food waste in landfill?

When buried in landfill, organic matter like food scraps breaks down anaerobically (without oxygen), releasing methane (a greenhouse gas 25 times more potent than carbon dioxide), and toxic leachate. Additionally, all this biomass and future fertility is lost from our food system.

We use a kitchen food waste disposal (e.g. InSinkErator-type system), is this better than landfill?

Food waste disposal units grind your food scraps up and add them to the wastewater system. While a substantial proportion of food waste is water (InSinkErator estimate 70%), the remaining 30% of solids then has to be screened out from the wastewater system, and then ends up in landfill.

How does composting help to combat climate change?

Composting helps up to reduce climate change in two main ways.

  1. Reduced emissions. By composting locally, and collecting by bike, we are reducing the carbon emissions that would normally be generated by trucking our waste out of the city, and by keeping organic material out of landfills, we are avoiding the methane that would normally be released - when it comes to trapping heat in our atmosphere, methane is estimated to be 25 times more effective than carbon dioxide.

  2. Carbon sequestration. Climate change is caused by an imbalance in the carbon cycle - we have upset the balance by burning fossil fuels, destroying the biosphere (through deforestation and more), and releasing carbon from our soils by over-tilling and the use of chemical fertilisers and pesticides, placing too much carbon in our atmosphere and our oceans.

    Plants pull carbon dioxide from the air through photosynthesis and transfer a portion of the carbon to the soil through their roots. Soil microorganisms then turn the carbon into a stable form commonly known as humus. Compost plays a vital role in creating the conditions for plants to do this. Watch this short video from Kiss the Ground for a great brief explanation.

What about soil degradation?

Degradation of our soils is mainly caused by over-tilling and chemical-heavy farming (amongst other causes), and poses a threat to our future as serious and urgent as climate change. According to the UNFAO, if we continue to degrade our soils at current rates, we have only 60 years of harvests left globally, and in many places it is much less than that.

Used alongside other regenerative practices composting is a powerful tool to help us to prevent further erosion and to create new topsoil.


Other questions:

Is Soil Factory a business?

Soil Factory is operated as a social enterprise by Kelmarna Gardens. This means that we operate like a business, providing services in exchange for payment, but we are a purpose-driven, non-profit organisation. Any profits generated by Soil Factory fund Kelmarna Gardens’ work to connect people with nature and food growing, and support people with experience of mental illness and intellectual disability to garden for therapy.

I want to compost at home but I’m not sure how to start.

Composting at home is often the best solution, and a great way to return fertility to your own garden. Compost Collective run excellent free workshops across Auckland where you can learn how to get started, or get help with resolving any problems you’ve had. We’re always happy to chat compost too if you’re struggling.


Still have questions? Get in touch.

Photo courtesy of EcoMatters Environment Trust.