Composting with Maddy from Kelmarna Gardens.

Composting is an excellent way to reduce food waste and create nutrient-rich soil by recycling organic materials back into the soil. As we supply compostable packaging, we are always looking at ways to help educate our decent community and learn more about composting. 

Our team in New Zealand caught up with Maddy at the beautiful Kelmarna Gardens in Tāmaki Makaurau (Auckland) to learn about composting at Kelmarna. 

Hey Maddy, can you please tell us a bit about yourself and how you got into working at Kelmarna Gardens?

I started volunteering at Kelmarna Gardens in 2020 with Andy Boor, the founder of Soil Factory. Soil Factory is the community composting enterprise run by Kelmarna Gardens composting for local residents and business. 

At the time, I was going through rehabilitation for an ankle fracture which prevented me from working. Volunteering at Kelmarna Gardens, namely composting, helped me build up my physical and mental strength, it was a form of therapy for me which I realise now in reflection. I ended up getting obsessed with composting as it gave me a sense of optimism and purpose which I was yearning for. Three years down the line, I’m still here but working full-time at the gardens digging deeper into regenerative agriculture and growing food.

For our out of town readers, can you tell us a bit about Kelmarna Gardens?

Through rebuilding connections between our people and our food, we work to champion and demonstrate a regenerative local food system that supports climate change mitigation, urban resilience, and community wellbeing.

Set on 4.5 acres of public land, our community farm has worked to provide delicious, healthy food and be a place of learning and well-being for our community for over 40 years.

Why is composting so important?

• Compost is a crucial tool to counter global warming, as it adds stable carbon to the soil and triggers a mechanism for carbon creation. 
• Compost creates disease resilient plants, reducing the need for chemical intervention. 
• Compost, and the humus it contains, dramatically improves water retention in soil. 
• Compost helps to detoxify soil that has been chemically contaminated. 
• Compost can increase the nutritional value of food. 

How does the composting system at Kelmarna work?

At Kelmarna Gardens the system of composting we use is called hot composting. Hot composting is a system where you mix materials high in nitrogen (food scraps) and carbon (leaves, paper, wood chip) together in a closed system. Through turning and incorporating air into the system aerobic (air-loving) microbes break down the materials, which generates heat. Temperatures reach about 55c - 65c at their highest which breaks down any herbicides or pesticides sprayed on our food scraps. We then allow our compost to mature for 3 months allowing networks of fungi to establish. This process produces a dark rich organic compost at the end. 

A few months ago we provided an event at Kelmarna Gardens with our decent packaging. From your experience, how do you find our products composted?

We found that your products broke down well and we struggled to find any materials present in our final compost product which was great. We also love how you guys are prioritising ensuring no nasty additives are in your products like PFAS, so we know we're not growing food in compost with gnarly chemicals from compostable packaging - that's really important to us.

What are some interesting facts about composting that our readers may not know? 

As the microorganisms digest the material in a hot compost pile, they produce heat, carbon dioxide, and excrement. This is why hot compost piles will heat up. We’ve witnessed some piles get as high as 75c! All through the power of microbes! 

What are some at home composting tips you can give to our readers?

The biggest mistake I see with home composer's is not adding carbon to their compost. It’s a simple one but super common. Whenever you add food scraps add an equal volume of a mixture of leaves, branches, wood chip, wood shaving or cardboard - the more diverse the array of carbon the better!