After three years of learning, Whanganui food waste composting business Easy Earth can sell a compost customers are "quite keen" on, co-owner Derek Pickering says.
The compost is a potent mix, with 75 per cent organic material with a rich nitrogen base.
It's not commercially screened, and sells for $50 a cubic metre.
The business started in 2018, and now composts food waste from 60 households, 25 businesses and 30 schools across Rangitīkei, Whanganui and South Taranaki.
One of the business customers is the Fonterra factory near Hāwera.
Easy Earth employs four people, two of them for 35 hours a week and the others part time.
It's looking for more Whanganui customers.
Easy Earth will be keen to tender if Whanganui District Council decides to start a ratepayer-funded food collection service in 2024, Pickering said.
That service would cost ratepayer households $40 a year, with food picked up from the kerb.
If that happened, Easy Earth would have to expand. Its Karoro Rd site in Castlecliff is getting full.
The main aim of the business is to divert food waste from landfill.
For most councils, food makes up 30 per cent of what goes to landfill.
Once there it breaks down to create a liquid called leachate, and two greenhouse gases - methane (CH4) and carbon dioxide (CO2).
Pickering said Easy Earth's HotRot automated composting system takes in 2 tonnes of waste a day.
The food waste is bulked up with arborist mulch, bark and untreated wood shavings to make the right mix for fast decomposition.
The system can handle meat, fish, dairy waste and cooked food.
The waste loses bulk as it decomposes and the business has an output of 7 tonnes of compost a week. That is piled up in windrows to cure, and is usually still hot from the process of decomposition.
Temperatures over 70C kill the useful bacteria. When it gets that hot compost quality technician Joe Thompson turns and irrigates the windrow to cool it.
Food waste from the Government's Healthy School Lunches programme comes in "compostable" packaging made of high-carbon plant material. The packages can be successfully composted if they are less than 10 per cent of the total.
Despite "compostable" packaging being a government requirement, most of it does not get composted.
"It's really great that we can compost it here in Whanganui," Thompson said.
He sends away compost samples for testing at labs, and also talks to people who use it.
Easy Earth compost has a carbon-to-nitrogen ratio of 20:1. That's a very good balance, Pickering said, and it also has phosphorous, potassium, trace elements and useful fungi and bacteria.
"When I have showed farmers the results they tend to be quite happy or excited."
Trials at Piwakawaka Farm have also shown the compost is very weed free.
It is not screened/sieved, which would take more time and equipment.
"We have found that our customers are quite keen on the product that we are producing and the price, so we thought we will stick with what we are doing at the moment," Pickering said.