The soil inside Springhill Prison is poor stuff, the grey and dusty dried clay left behind when the land was scraped for the buildings.
But around two of the special units, the earth is gradually turning darker as compost and worm tea is added to newly-dug vegetable gardens.
Guard Phil McEvoy saw the efforts prisoners were making to grow plants, so tried to help by making a simple worm farm.
"When it rains the worms crawl over the concrete paths, so I collected them up and put them into a couple of 20 litre plastic containers," says the burly Merseysider, who joined Corrections three years ago after running pubs and takeaways.
Someone higher up heard about his efforts, and money was found in the rehabilitation budget to buy two modules of eight Hungry Bins from Onehunga-based Low Impact, which went in last October.
When Element visited the prison with Hungry Bin inventor Ben Bell, the first thing we saw was a large tray of onions and cauliflowers waiting to be taken to a food bank or women's refuge.
As Bell checks the temperature, worm health, density and the mix of waste going in, prisoners come by to discuss progress and pick up any knowledge he is able to dispense.
Hungry Bin's Ben Bell chats to prisoners
"They're looking better since you moved them into the shade. The worms don't like it too hot," Bell says, rummaging through the chopped up cabbage leaves with his gloves until he can pick up a good handful of compost worms. "I can't see any maggots. That's good. It smells sweet."
Some broad beans catch his eye. "I put them in there to germinate," says prisoner S, who has assumed responsibility for the unit's worm farms.
Over by the fence, the soil is heaped into metre wide rows and planted with seeds rescued from the kitchens or bought in by guards. ?They're supervised by prisoner G, an older man who maintains a strict regime of planting by the moon, passing on to other inmates the Maori gardening knowledge he learned growing up in the north.
"Those are peruperu, which came on the Mataatua waka," he says, pointing to an area where the purple potatoes will soon start peeping out of the soil. ?"Things are grouped in the proper days for growing, and not planted out of season. That helps with the bugs," he says.
When he started the garden, there was only one broken spade to turn the soil. The prisoners now have access to a rotary hoe. ?"It's not about monetary gain. The gain is what we will take out of it from here.?"This fellow has a problem being around people, but he is coming out of that," he says, indicating prisoner S. "If you give people initiative, they come out of it.?"There used to be no order, no respect in this place. Now there is a lot of respect and people are not coming and helping themselves to the gardens."
Over in the next unit, prisoner R shows us his experimental pumpkin patch. ?He's been giving it regular sprinkling of worm tea, and in just one month the plants are standing a metre tall, with an abundance of pumpkins growing on the vines. ?He's now ready to douse the rest of the gardens with the miraculous substance.?"They call me the worm whisperer," he says, standing by the bins.? "I name every one, but I can't keep up. They reproduce overnight."
He says while only about half a dozen inmates work on the gardens, everyone is responding to the growth.? "Everybody walks around. They come out every morning and see something different is happening."
McEvoy says by keeping prisoners occupied, the gardens help reduce tension inside. The responsibility also teaches people work and life skills that will be useful on their release. ?Switching from compost heaps to the Hungry Bin worm farms also allowed the units to get on top of their rat problem.
Bell would like to see a lot more Hungry Bins in the prison. He has designed the system to be modular and scalable, so it can deal with large volumes of organic waste.? "There are nine skips a week going out of this place, half of it organic. The worms can eat that.?The Auckland Council premises at Graham St has shown what can be done on an institutional scale with 20 bins turning the waste from eight kitchens and 500 staff into compost, cutting the landfill waste coming out of the building by 25 percent.
Bell sees the Hungry Bins as part of wider vision to cut down energy waste and preserve nutrients. ?His work in the film industry did not chime with this upbringing on a lifestyle block near Whangarei where his mother was proud to serve up meals grown entirely on their own land, before going to art school to study photography.
He went to work at the Eco-Matters environmental trust on household energy schemes.?That's when he decided the worm farm he had at home could be improved on, so he made one from a wheelie bin.?Friends asked for them, and he found a source of broken bins and sold on Trademe.? When the stockpile ran out, he took the plunge, rounded up investors and set up Low Impact to manufacture a more refined design, with a grant from Waitakere City Council's waste minimisation fund.
"The Hungry Bin breaks some of the central tenets of worm farming. You are not supposed to compact them, but that's what my bins do, forcing the worms to come to the surface where they like to feed," Bell says.
Making a better worm farm wasn't the end of it. Bell has set it up to be energy efficient. Dismantled, the bin fits into a box that meets postage limits. For export, 400 of them fit into a single container.
"The idea from the start was to reduce barriers to uptake. Part of the vision is to get people to understand why they need to do this, and then remove the barriers that stop people composting."?He says a prison is an ideal location for worm farming.
"Corrections has room to spare, people willing to do it and space for gardens. It's a virtuous circle."