• Sustainable vegetables are most likely to come from organic farms. (Tim Thatcher)Source: Tim Thatcher
The carbon loss from soil degradation might be an oversight for those thinking about sustainable eating.
12 Aug 2019 - 1:15 PM  UPDATED 12 Aug 2019 - 1:15 PM

I’ve been writing and thinking a lot about meat, lately, and the impact of Australia’s voracious appetite for flesh and its impacts on the world. But farming and land use for fruit, grains and vegetables is a topic that seems to get off the hook in terms of sustainability.

When we look at what the world and each farming system can grow, we need to look at topsoil, what we have, how it is made, and how best to preserve this magical few centimetres (sometimes in Australia it’s only a few millimetres) that’s responsible for all the world’s food growing.

First, a few facts: The world has lost half the carbon once stored in agricultural land since the industrial revolution. Just let that sink in. Carbon, something we’d like stored in soil (despite us releasing a lot from long held storages such as coal, oil and gas), something that helps bind nutrients in soil, that helps soil retain moisture and is a pretty good indicator of soil health, has been stripped from our topsoil over the last 250 years.

The world has lost half the carbon once stored in agricultural land since the industrial revolution. Just let that sink in.

Why has this happened? An increase in machine tilled (ploughed) land has meant we can now release nutrients faster, but leave less behind for future generations. We depend on artificial fertilisers, which don’t bind to soil very readily and are quickly leached out. (These fertilisers are made using natural gas as the energy source, contributing about 2-3% of our global greenhouse gas emissions.)

Autumn harvest on Fat Pig Farm

We base so much farming on monocultures, which are grown year after year, without rotating crops or animals as we once did to replace nutrients that are lost. We also focus most of our growing on annual crops, which leave bare earth exposed, so it’s more likely to suffer from erosion, both of the wind and water variety. When we have dust storms over Sydney and Canberra, like we did in early 2019, that’s not really dust. It’s our topsoil blowing out to sea and over the ditch to stain the New Zealand glaciers.

So what are sustainable vegetables, then? First, a definition of sustainable should be that we can do what we’re doing now, forever. So anything that depletes soil or nutrients that can’t be replaced isn’t sustainable. Spraying pesticides, a scorched earth attitude to unwanted pests, is unlikely to be something we can do forever. The insects develop resistance. The same goes with herbicides and weed killers that cause large tracts of land around the world to be graced by ‘super weeds’, resistant to the most common types of herbicide.

Sustainable vegetables, then, are most likely to come from organic farms, or those that have biological principles and minimal sprays. They will come from places that place soil health first. They will, by definition, usually be grown close to where they are consumed, to cut down on the carbon emissions from transport and storage. And they will be eaten shortly after harvest and in the season in which they are supposed to be grown.

Sustainable vegetables, then, are most likely to come from organic farms, or those that have biological principles and minimal sprays. 

Perennial plants (as opposed to annuals) live on from year to year. So perennial agriculture, which can’t give us all our food, but can provide some of it, is a good part of the dietary mix. Plants such as artichokes, asparagus, warrigal greens, avocadoes, olives, and all the fruit trees are perennial food sources that can, in the right farming system, have minimal impact for the food they produce. Things like berries and rhubarb and even scarlet runner beans, live for years and keep sprouting from the same roots without the need to disturb the living soil. In climes warmer than Tasmania, growers can graft eggplant onto root stock to reap multiple years’ harvests, and in cooler climates like ours, a home gardener can get kale and even broccoli to last several seasons if they take care with the way it is gathered.

Sustainable vegetables are, in a nutshell, just like your granny would’ve recognised. They’re often organic. They are locally sourced, consumed in season, and abundant in variety to help replenish and not deplete soil. They’ll differ depending on where you live, but by definition, they should be something we can grow and harvest forever. For many, the very definition is something grown in their backyard to feed the family.

Matthew Evans is back showcasing homemade goodies in his brand-new series of Gourmet Farmer, 8pm Thursday nights from August 1 to October 3 on SBS, with an encore 8.30pm Fridays on SBS Food (Channel 33) and streaming on SBS On Demand. Visit the Gourmet Farmer website for recipes, the episode guide and more.


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Watch online: Harvest
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