Kat Lavers was doing her honours in human geography when she sat on her doorstep and watched a house sparrow flutter out of a wattle tree. It dived to the ground, pulled out a worm and flew off with its forage.
"I thought, wow, in 16 years of education I am not sure I can do anything as practical as what that little bird just pulled off," Lavers says.
So she shifted things around and got more practical. Lavers now produces her own fruit, vegetables and quail eggs in her Northcote garden but, ever the scholar, she also keeps a running tally on the weight of her harvest, the amount of land it takes up and the pH of her soil.
She knows the dimensions of every aspect of her block (271 square metres in total, 171 square metres of garden, 30 square metres of vegetable beds, which includes 10 square metres of paths … I could keep going …).
"There is so little data on what can be produced on a domestic scale," she says. "I am contributing to research at Melbourne Uni quantifying backyard harvests."
For the record, her vegetable beds can yield more than 170kg of produce in one year, her whole garden – fruit and nut trees, quail eggs and mushrooms included – more than 350kg of produce.
But to reach this point she has been resolutely methodical. She has introduced what she calls an "urban permaculture system" that includes everything from a slow-combustion wood stove in her living room (which acts as heater, cooker and food dehydrator), a sink outside her back door (where she washes the soil from her produce before reusing the water) and a covey of Japanese quails (quieter and smaller than chickens).
Lavers' permaculture set-up is one of the case studies in a new book Retrosuburbia: the Down Shifter's Guide to a Resilient Future by David Holmgren. In this thorough, how-to manual, Holmgren details what we can all do – in both our houses and gardens – to make our suburbs "more productive and resilient". The book provides information on everything from grey-water recycling to keeping goats and the importance of healthy soil.
Lavers' quails came about in part because of soil contamination from lead-based paint flaking from her neighbour's weatherboards. Lavers had both the paint and her soil analysed and keeps the quail in a pergola-turned-aviary with a concrete floor topped with multiple layers of wood shavings, woodchips, dried leaves and other plant material.
Urban soils were one of the key topics at last month's Urban Agriculture Forum, where soil scientist Declan McDonald said soil was "the most complex ecosystem on the planet".
"Far more complex than tropical rainforest, a vast range of species live in our soils that, previously, we never knew existed," he said.
In order to foster life in the soil, he suggests having a diversity of plants, including green manures ("diversity above ground equals diversity below the ground") and maintaining year-round soil cover with no areas of bare earth.
Peter May, who taught soil science at the Burnley Campus of the University of Melbourne for 30 years, told the conference that all urban soils were "contaminated" with "higher levels of worrisome things" than in the past. "But that doesn't necessarily mean they are dangerous," he said.
May says it is only by measuring the nutrient status and contamination of your soil that you can you work out how to best manage it for growing food. He advises gardeners to send soil samples to laboratories that can assess where they sit within accepted levels.
Lavers says the elevated lead levels in her soil have "significantly impacted" the way she has designed and managed her garden. Sometimes attaining high yields can be all about keeping tabs.
RetroSuburbia: The Downshifter's Guide to a Resilient Future is available from RetroSuburbia.com, $85.