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Tuesday, December 7, 2021

The solution to climate change? It could be right under your feet

This is a very timely book. Farmers are pondering regenerative agriculture, gardeners are discussing “no dig” and we are all worried about reaching carbon “net zero”. But few of us know what we are talking about, largely because the scientific community has spent more time studying the stars than the soil on which our survival depends. As Matthew Evans observes: “For me, soil seemed dull and insipid.” Yet, “Good soil isn’t just an abstract concept; it’s a thing of wonder … There are more living things in a teaspoon of healthy soil than there are humans on Earth.”

Evans is the right man to explain. An Australian with an interesting CV, reflecting an insatiable curiosity: from chef-cum-food writer and broadcaster to Tasmanian farmer and now one of the best commentators on anything between the soil and our stomachs. He first came to attention over here with On Eating Meat, one of the best critiques of modern farming you will ever read. Evans is not an academic – which perhaps explains his didactic talents as he deftly guides us through the story of soil with simple explanations and the enthusiasm of a Blue Peter presenter – but has dug deep to understand the science and present it to us in an easily digestible format.

And what a story it is. Evans ranges freely from geology to nutrition via agronomy on an evangelical mission to show how central soil is to life. He explains how smelling healthy soil is good for our sense of wellbeing and how soil microbes have been found to be the nuclei of raindrops. He takes us to the University of Tennessee’s Forensic Anthropology Centre’s “body farm”, where volunteers leave their corpses for research into how bodies decompose, to give us a stark reminder that we are only briefly “not soil”. And he suggests, only partly tongue-in-cheek, that we should consider using human remains as fertiliser, particularly as cremation releases carbon and nitrogen into the atmosphere leaving calcium phosphate, which is “not available to plants in that form”. And then there is the discussion of “humanure”, which is best read between meals.

If some of it is shocking, it reinforces Evans’s main thesis that healthy topsoil has either been vanishing at an alarming rate, or poisoned by chemicals, and that we must make more of it. He shines a merciless light on the damaging side effects of the “green revolution” and particularly on its main architect, the Nobel laureate Fritz Haber, the inventor of the process that creates the nitrogen to produce “about one mouthful out of every two a human eats”. Haber’s invention of poisoned gas caused his wife, also a chemist, to kill herself a week after its first use at Ypres in 1915.

As a knowledgeable foodie, Evans traces the links between healthy bacteria in the soil biome and the nutrients we need for health and rattles off some very depressing statistics showing how the food we eat is far less nutrient dense than in our grandparents’ day. He is dismissive of air proteins, “lab food” manufactured using electricity when we should be utilising the sun’s energy to grow better food.

Happily, contrary to the zero-sum arguments we often hear from environmentalists, we can make more topsoil relatively easily. Some of the most interesting parts of the book are about how prehistoric peoples in West Africa and South America independently discovered different methods of creating rich dark soils from charcoals, manures and composts, something we have been slow to investigate in the modern era.

Most importantly, Evans explains how regenerative agriculture that draws carbon out of the atmosphere into the soil so that it is “like chocolate cake’” (through minimising soil disturbance and exposure, diverse cropping and grazing livestock) is our best hope of reversing climate change. He quotes Stéphane Le Foll’s “quatre pour mille” idea: that if all the world’s soils under human management were to increase in soil carbon by just four parts per 1,000 (0.4 per cent) annually, virtually the entire global increase in carbon emissions for each year could be offset. Suggestion for Mr and Mrs Thunberg: please pop a copy of Soil into Greta’s stocking this Christmas.

Soil is published by Murdoch Books at £14.99. To order your copy for £12.99 call 0844 871 1514 or visit the Telegraph Bookshop

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