Down to earth: Why we need to act to save this precious resource

How a former restaurant critic found his roots – and became alarmed by what he discovered. By Greg Dixon.

We treat soil like dirt. We poison it with heavy metals, strip it of life with herbicides and over-fertilise it with artificial nitrogen. We harm it by growing only single crops, hurt it through overgrazing and seem happy to watch it disappear before our eyes as man-made erosion blows or washes it away. We even degrade it with our language; to "soil oneself" is not to get one's hands a little dirty planting begonias or digging new potatoes.

Yet soil is the stuff of life. This thin, magical layer is what sustains all life, protects us and heals us. It could just be the most important thing on the entire planet. Which begs the question: why do we ignore it at best, and pollute or destroy it at worst? Well, as flippant as it sounds, the good earth is in need of a good PR man.

"Let's face it, soil has an image problem," says Matthew Evans, an Australian farmer, chef, food activist and author of a new book on the marvels of the stuff that lies beneath our feet. "[Soil] doesn't speak. It doesn't give us visceral pleasure like a forest or a waterfall," he writes in Soil: The incredible story of what keeps the earth, and us, healthy. "It isn't poetic. It's the stuff we've wiped our collective feet on for a couple of thousand years, and often – to our detriment – ignored."

We have been disregarding, perhaps even disdaining, something that is not sterile or dead, but something unique, and something positively heaving with life – at least when it's healthy.

Hidden universe

Although soil forms just a tiny fraction of the planet, it is the most densely populated and heterogeneous environment, Evans says. A teaspoon of healthy soil holds more living things than there are human beings, as many as 10 billion living things, from nematodes to fungi to multitudes of bacteria. It is like a hidden universe.

Soil, of course, helps feed plants, which in turn feed us and animals. But soil can support five times more life below ground than it does above; a hectare of healthy pasture can feed just 20 sheep, but under the surface that same healthy hectare supports microbial life equivalent in mass to 100 sheep.

There is huge diversity in healthy soil. A single shovelful contains more species than all those found above ground in the entirety of the Amazon rainforest.

But soil isn't just the busiest biosphere on the planet, and it doesn't just sustain all other life. It also sequesters carbon, while the microbes inhabiting it can do some pretty wild stuff, like make rain and – as improbable as this sounds – make you feel good.

"We underestimate the living nature of soil," Evans tells the Listener from his farm in the southernmost shire of Tasmania.

"We've thought of it in terms of only the geological – that it is of rocks and mineral – and of chemistry. We've underestimated the biology of it, the living nature of it, and we have imperilled soil because of that."

Politics of food

If you were going to pick a PR guy for soil, you could hardly do better than Evans. Although Soil is haunted by the harm we have done and is a full-throated SOS to "save our soil", it is also an ebullient and lively celebration, a paean to the virtues and potency of Mother Earth. In conversation, Evans is just as passionate and persuasive.

Still, you don't have to dig too deep around his roots to discover he's also something of an accidental champion of soil. In fact, for much of his life, he readily concedes, he, too, has been guilty of treating soil, if not like dirt, then as an afterthought.

Born in Canberra 55 years ago, he has a degree in applied science, but trained and worked as a chef before becoming one of Sydney's most feared restaurant critics in the early 2000s, writing for the Sydney Morning Herald and editing its annual standalone directory, The Good Food Guide. "I am, essentially, a glutton by trade; that's what I've done with my life," he says. His tour of duty at the SMH took him through thousands of restaurants, though among Sydney diners and restaurateurs he's likely best remembered for the review of just one, Coco Roco, in 2003. This resulted in a decade-long defamation case, which eventually cost the paper more than A$600,000 in damages, interest and costs.

He left the paper in 2005, later publishing, in 2007, a part-memoir, part-exposé of the restaurant trade with the alarming title Never Order Chicken on A Monday. That same year, he lit out for Tasmania to find and live a simpler life. "I kind of joke that I got to my early forties, had a midlife crisis and got interested in gardening," he says.

Since 2011, he and his wife, Sadie Chrestman, another townie, have farmed 28ha in the Huon Valley, south of Hobart. Called Fat Pig Farm, they have developed a mixed holding, raising Wessex saddleback pigs, chooks and cattle, along with a small market garden. The couple's lifestyle has since morphed into a full-time business, which now includes a cooking school and small restaurant, with their transition from townies to farmers charted in five series of Gourmet Farmer, a TV show made for Australia's SBS network.

Former restaurant critic Matthew Evans: "Let's face it, soil has an image problem." Photo / Greg Bowker

Evans has become something of a minor publishing phenomenon in Australia, too, with 13 books to his name, most on food or the farm. One of his most recent, on the ethics of eating meat, which followed a one-off documentary on the same subject, signalled his growing interest in the politics of food.

It has only been a small leap, then, to researching and writing Soil. In a sense, all his years of eating, cooking, reviewing and, finally, learning how to grow food on Fat Pig Farm appear to have led him to the thing that makes growing, cooking and eating good food possible.

"When I was a restaurant reviewer in Sydney, the chefs, they were all great, talented chefs, but they'd all say, 'We've got the best produce in Australia,' and I started to realise that, no, the best chefs don't have the best produce. The people who have the best produce are those who are growing it themselves and eating it in their home kitchen.

"And that led me to the genesis of everything: soil. Growing and cooking and eating, it all boils down to the stuff I took for granted and never considered as a living, breathing thing beneath my feet."

Underground economy

The life of soil, at least healthy soil, is amazingly complex. Yet its constituents are simple. About 95 per cent of soil is minerals from crushed rock, 5 per cent is organic matter – previously living leaves and animals – and 0.5-1 per cent is living microbes. About 25 per cent of healthy soil, by volume, should be air – a vital component.

However, soil is nothing without plant life. "Put simply, bare earth is bad," Evans writes. "Plants try to cover bare earth, and bare soil wants to be covered."

It is the interaction between the two – soil and plant life – where the complexity begins. Evans confesses that for a long time he thought plants simply ate dirt, which is what, if pushed, most of us would think. But what he learnt, as he talked to other farmers and began reading countless research papers, was that plants and soil form a delicate "underground economy", a trading system between the things that live below ground and plants. Through photosynthesis, plants use sunlight to transform carbon dioxide into sugars to feed themselves and grow. But, as Evans explains in Soil, plants trade at least one-fifth of those sugars with the microbes around their roots. In return, bacterial and fungal networks supply up to 90% of what plants need from the soil. These networks can even help plants share nutrients with each other. The result – when left to itself – is a healthy, growing, interdependent ecosystem above and below ground.

"The intricacies of it are impossibly complex," Evans says. "We still don't know 98% of what lives in soil. That blows my mind. What we do know is that soil is a self-organising superorganism."

Feel-good factor

Soil contributes to our and the planet's health in other surprising and only recently discovered ways, Evans has found.

Soil bacteria have, of course, proved useful for decades in creating antibiotics for human medicine, but soil's microbes do much more. In 2004, British medical researchers, hoping to find that an otherwise harmless and common soil microbe, Mycobacterium vaccae, would fight lung cancer – it didn't – instead found it acted like an antidepressant, boosting both serotonin and norepinephrine, hormones that make mammals, including humans, happy. Another, 2016 study found M. vaccae also has positive effects on our immune system and an anti-inflammatory response, too.

Natural disasters such as floods in Belgium are increasingly attributed to climate change. Evans says, "Carbon out of the air and back in the ground is what we need to heal the world." Photo / Getty

One of the seriously freaky things that soil bacteria have been found to do, Evans discovered, is defy gravity, floating high into the air, where they help form the nuclei of rain, snow and hail. "Microbes have created this magnificent biofeedback loop, where they provide the nuclei for rain, while at the same time, the bacteria are able to move long distances in the clouds to colonise new plants and soil," Evans writes.

Perhaps soil's most important, secondary contribution to life on the planet – certainly in light of the Intergovernmental Panel on Climate Change's report in August, described by UN Secretary-General António Guterres as a "code red for humanity" – is its ability to sequester carbon. The living and dead things in soil contain 4.5 times more carbon than the rest of Earth's biosphere put together and could, with human intervention, hold much more. "Carbon out of the air and back in the ground is what we need to heal the world," Evans says. But first we need to stop treating soil like dirt.

Poisoning the soil

Here is a truly shocking number: the planet's topsoil is being lost as much as 40 times faster than it is being replaced. On a yearly basis – and this a conservative estimate, Evans says – up to seven tonnes of topsoil for every man, woman and child ends up in rivers and oceans. Meanwhile, 12 million hectares of land is lost to desertification each year. When we then consider that only about 7% of the Earth's surface is available for growing food, you don't have to be a genius to figure out the rate of soil loss is unsustainable. "Soil is buggered in a worldwide sense," Evans tells the Listener. And that is all our fault.

Soil is being lost as a result of man-made deforestation and the erosional effects of man-made climate change. It is also being quietly poisoned through the use of agricultural and horticultural chemicals. For example, high use in the past of superphosphate fertiliser on some New Zealand farmlands, principally in the dairying regions of Waikato, Bay of Plenty and Taranaki, has resulted in significant accumulations in the soil of cadmium, a heavy metal that is toxic to humans. Copper build-up is another example. Used by wine growers as an anti-fungal agent, copper can build up in the soil "to such an extent it poisons young vines", Evans writes.

But the major damagers of food-growing topsoil are the mainstream agricultural practices, both old and new, used to grow food. Perhaps the most harm, over the long term, has been done by the humble plough, the ancient tool that has helped feed humans for thousands of years. It leaves soil "vulnerable to erosion, kills the complex ecosystem underground" and emits carbon into the atmosphere.

A slip on Takaka Hill in the Tasman District earlier this year. When soil is exposed and disturbed, it increases slips and erosion. Photo / Supplied

The so-called "green revolution", which has used hybrid and higher-yielding crops and untold tonnes of artificial fertilisers to hugely increase worldwide food production since the 1950s, has done ongoing harm, too, Evans says.

The green revolution's encouragement of single cropping – creating endless fields of just one crop, such as corn or wheat or canola – harms soil life. But it is the synthetic nitrogen fertiliser used to support single cropping, including on New Zealand's farmlands, that is the main culprit. Although "billions of people probably owe their lives" to artificial nitrogen's ability to stimulate plant growth, it has harmed the environment by turning waterways toxic. It can also become nitrous oxide, a potent greenhouse gas. But worst of all, it reduces life in soil, and turns soil and plants into nitrogen junkies, with farmers following what Evans calls the "moron principle" – to keep putting more on – even though adding more artificial nitrogen fertiliser has an ever-decreasing effectiveness over time.

"Artificial nitrogen seemed like a good idea," Evans says. "It seemed like we could grow plants bigger and faster, or in soil that is unsuitable for a crop. But the problem is that it is a very short-term gain and you either kill soil off or you turn it off and it is a losing game.

"You can ruin soil in a handful of years, but it usually takes longer than that. And what you are doing is impoverishing generations to come by using so much fertiliser."

Carrot and stick

As bleak as that may sound, Soil is an optimistic book. What it is not is one that sets out to blame any one group for what has happened. "No one has ruined soil on purpose. Well, most people haven't," Evans tells the Listener. "They've done it by accident or mistakes or because that's the way their grandfathers did it."

Still, we face a huge challenge to save what soil we still have and still be able to feed a global population that will approach 10 billion by mid-century.

Is the answer organic farming and permaculture approaches? "I think that is a little bit of a narrow view. The first thing is that people need to care, then we can expect more: more of governments, more of growers, more of the food we eat.

"How does the average person fix it? Diversity. Soil wants to grow a diversity of things. So what you need is people eating a diverse variety of vegetables, grains and fruits. That allows the farmer to grow a greater diversity of things." We need to reduce waste, too. About 40 per cent of food is thrown away, perhaps as much as 60 per cent.

Another key is to start making soil. "We already have the technology and know-how to build soil in a time frame way faster than nature can make it."

Finally, we need to have a bigger view of soil. "It's not what happens this year or in five years," he says, "it's what happens in 50 years or 500 years, because that is the time scale that matters with soil."

If not, we are heading for a cliff. "But we know how to put the brakes on; we know how to turn things around. It is a matter of whether individuals, communities and governments decide to make that choice.

"We are custodians of the land. Essentially, farmland is the national estate. So farmers are responsible to the nation, whose land they, farmers, currently steward. But you do need leadership. You need the carrot and the stick." And some good PR, too. l

Soil: the incredible story of what keeps the earth, and us, healthy, by Matthew Evans (Murdoch Books, $36.99).