When you take a step back from these facts, you see something remarkable. The rhizosphere lies outside the plant, but it is as essential to its health and survival as the plant’s own tissues. It is the plant’s external gut5. The parallels between the rhizosphere and the human gut are uncanny. For example, there are over a thousand phyla (= major groups) of bacteria. But the same four phyla6 dominate both the rhizosphere and the guts of mammals. This much we know, but with every year soil scientists make remarkable discoveries that force us to revise our understanding. Soil has properties that are shared with no other ecosystems and no other structures. Some of these properties, especially its coordinated response7 to environmental stress, suggest that we might in time come to see it as a kind of super-organism. Little on earth is as dark to us as soil. Upon this scarcely-understood system, we rely for 99% of our calories8. Yet we treat it with indifference, even contempt. Soil science is shockingly underfunded. There is no soil ecology institute anywhere on earth. While there are international treaties on telecommunication, civil aviation, investment guarantees, intellectual property, psychotropic substances and doping in sport, there is no global treaty on soil. We behave as if this amazingly intricate biological structure can withstand all we throw at it and continue to feed us. It can’t. There are many ways in which we trash it. There’s the physical damage caused by careless ploughing. There’s contamination and urban sprawl. There is the growing of crops – especially maize and potatoes – in ways that leave the soil broken and exposed to winter weather. There’s the overuse of fertilisers: too much nitrogen prompts microbes to burn through the carbon that glues the soil structure together. There are the pesticides that kill soil animals as surely as they damage ecosystems above ground. On farmland almost everywhere, soil is degrading at astonishing speed. But the impacts tend to be greatest where they hurt the most – in the poorest countries. This is partly because many of them are in the hotter regions of the world, where extreme rainfall, cyclones and hurricanes can rip exposed earth from the land, and partly because hungry people are often driven to cultivate steep slopes and other fragile places. One paper finds that erosion rates in the world’s poorest nations have risen by 12% in just eleven years9. In some countries, mostly in Central America, tropical Africa and South East Asia, over 70% of the arable land is now suffering severe erosion10. Climate breakdown, causing more intense droughts and storms of wind and rain, will exacerbate this loss11. Already, as a result of drought, soil erosion and the overuse of land, desertification affects one third of the world’s people12. Soil damage in dry places is one of the reasons why grain yields in sub-Saharan Africa have mostly failed to increase since 1960, even as they have boomed in the rest of the world. We are weakening the soil’s capacity to renew itself, undermining its structure and making it more vulnerable to external shocks. The loss of a soil’s resilience might happen incrementally and subtly. As with other complex systems, we might scarcely detect the flickering until a shock pushes it past its tipping point. When severe drought strikes, the erosion rate of fragile and degraded soil can rise 6000fold13. In other words, the soil collapses. Fertile lands turn, almost overnight, to dustbowls. Our survival during the past hundred years has relied to a large extent on understanding and enhancing soil chemistry. Chemical manipulation has delivered extraordinary advances in crop production, but at a terrible cost to our long-term resilience. Feeding the world in the decades and centuries to come will depend on a much better understanding of soil biology. It will depend on a recognition that our survival is intimately connected with that of the creatures which build and sustain this scarcelyknown ecosystem. We do not care about what we do not know. The gaps in our understanding of the world beneath our feet are so wide that humanity could fall through them. George Monbiot (London, b. 1963) is an author, Guardian columnist, and environmental campaigner. His best-selling books include Heat: How to Stop the Planet Burning (2006) and Feral: Rewilding the Land, Sea and Human Life (2013). His latest book is Regenesis: Feeding the World Without Devouring the Planet (2022). In 1995, Nelson Mandela presented him with a UN Global 500 Award for outstanding environmental achievement. In 2022, Monbiot was awarded The Orwell Prize for Journalism. Monbiot cowrote the concept album Breaking the Spell of Loneliness (2016) with the musician Ewan McLennan, and has made a number of viral videos. One of them, How Wolves Change Rivers, adapted from his 2013 TED Talk, has been viewed on YouTube more than forty million times; another one on natural climate solutions (#naturenow, 2019), in which he co-stars with Greta Thunberg, has been watched more than sixty million times. 30 31
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