Soil, food and cities: Treating a city’s food waste to improve soils

Volume 11 Number 2 February 9 - March 8 2015

Photo: Peter Casamento
Photo: Peter Casamento

 

Agricultural researchers are exploring technologies to support large-scale food waste as a soil conditioner, in the hope of being able to improve soil management as an integral part of the food chain. By Andi Horvath and Daryl Holland.

Right now some of the food in your fridge is edging towards the classification of ‘I think this is still okay’. Some has already passed the point of ‘beyond human consumption’, because sometimes our best-intentioned culinary missions miss that window of opportunity. The diligent among us re-purpose foods such as over-ripe bananas to make banana bread or enhance compost.

But food waste is not just householders’ forgotten food and restaurant slops; it includes the food that doesn’t make it to any kitchen or dinner table.

There is food wastage at every stage of our modern food production system: from harvesting at the farm to storage and displays at supermarkets. Consumer perceptions play an important role. That odd-shaped and slightly blemished, yet fresh and edible, apple you deem unworthy of purchase contributes to the 20 million tonnes of Australian landfill annually. And food waste in landfill is an enormous source of greenhouse gases like methane and CO2.

To combat these problems, could we turn an entire city’s food waste into a soil resource? 

The value of food waste for land application is still largely uninvestigated. It’s a timely research question for the ‘International Year of Soils’ and Dr Tony Weatherley, a soil scientist within the Faculty of Veterinary and Agricultural Sciences at the University of Melbourne has recently received an award from the Lord Mayor’s Charitable Foundation to start finding out. 

Currently it is a scientific question but it will eventually become one of infrastructure and logistics.

Dr Weatherley describes how he landed this exciting research project, entitled ‘An evaluation of the potential of food waste as a soil conditioner’.

“It’s a rather interesting story as to how I got involved in this area, as a couple of events coincided,” he says.

“Firstly there was a local council initiative to participate in a composting trial. I chose the compost bin option rather than the worm farm approach thinking it would be more of a ‘set and forget’ project. 

“But composting doesn’t work like that – I didn’t have enough food waste and it didn’t reach the right temperature, and because of this, I became fascinated. 

“At the same time a city restaurant, Cecconis, approached a colleague and myself, because they wanted to ‘close the loop’ when it came to food production. That is, use great fresh product, return the food waste to the soil and then grow more great vegies. They had purchased a composting unit that transforms all the food waste from the restaurant into a potential ‘soil conditioner’ (at least that’s what we’d call it) and they wanted to know how to optimise its effectiveness,” Dr Weatherley says.

“It turned out the City of Melbourne, University of Melbourne student union and a number of other city restaurants were attempting to recycle food waste using similar technologies. So this research will determine the types of soils that will benefit from food waste application and most importantly how often the waste might be applied to soil. It will also assess things like odours, greenhouse gases, contaminants, and the availability of nutrients like phosphorus, potassium and nitrogen to soil and plants. We are particularly keen about examining the role of fungi in soil chemistry,” Dr Weatherley says.

The research program has just started and our Burnley campus will be involved in small plot evaluations. Initially we intend to study the role of food waste in returning phosphorus to the soil and its effect on phosphorus use efficiency for plants. This may help to address future scarcity of this element.”

So what would Dr Weatherley like us to ponder during the International Year of Soils?

“Soil is a dynamic living thing,” he says. “Soils have a tipping point just as our own health does, and beyond a certain point soil can’t be repaired or replenished – it’s not an unlimited resource. Understanding soil science is more important than ever: our future environmental and economic wellbeing depends on it. We can’t keep treating soil like dirt, pun intended.”

 

fvas.unimelb.edu.au