“We can’t eat those carrots,” the kids cried out. “They’re covered in dirt!” My friend had been regaling me with stories about teaching public school kids healthy eating and gardening and this particular comment struck a chord: Kids are so used to devouring carrots from plastic bags that they’re shocked to see the vegetables with soil still clinging to their orange flesh.
What we dismiss as dirt is perhaps the most valued – and underappreciated – part of nature.
Just a thin band of soil stands between our species’ survival and total extinction. We depend on soil for food security, biodiversity, and climate stability. Globally soil organic matter contains three times more carbon – 1,500 billion tons, to be exact – as all trees, shrubs, and grasses combined. Yet we’re paving it over with urban sprawl. We’re draining rich soils for oil-palm plantations in Indonesia and cutting down vital rainforests for feed-crop plantations in Brazil. We’re devastating farmlands with a barrage of chemical fertilizers and pesticides. Half of all the world’s topsoil has been lost in the last 150 years alone, according to the World Wildlife Fund.
Propelled by these losses, the United Nations and partners around the world declared 2015 the International Year of the Soil.
“When I started out in organic farming 40 years ago, we talked about healthy soil being key to healthy people,” Andre Leu, president of the International Federation of Organic Agriculture Movements, told me. “Back then, we were ridiculed. Today, it’s become common sense that soil health and human health are interlocked.”
Though we appreciate soil more today, it doesn’t mean soil is being treated like the royalty it is. To date, there’s no mention of soil in United Nations climate change conventions. In fact, the only international agreement that refers to soil is the United Nations Convention to Combat Desertification, and it focuses only on dry areas. Advocates hope bringing attention to soil this year will change that.
The good news is it’s possible to protect soil – even rebuild it – far faster than once was thought. It starts with understanding that healthy soil is alive. A handful of topsoil can contain more microorganisms than the number of people on the planet. Try to wrap your head around these numbers: In one cubic meter of temperate climate topsoil you’re likely to find more than 10 trillion bacteria; 100 billion fungi; 100 million algae; 1 million nematodes; 10,000 springtails, mites, and millipedes; along with fly and beetle larvae; earthworms; spiders; and lice. This life is key: To kill it with a chemical onslaught or too much tillage is to undo soil health.
These microorganisms, especially mycorrhizal fungi, are what Indian environmentalist Vandana Shiva calls the “brains of the plants.” These fungal roots bring nutrients and water to plant cells and form a kind of communication network, which we’re only just beginning to appreciate. One British study of broad bean plants found that mycorrhizal filaments can send an inter-plant signal when one plant is attacked by aphids, triggering nearby plants to mount their own chemical defense, repelling aphids and attracting wasps, their natural predator.
Though mineral subsoils can take centuries to form, using techniques like permaculture and organic agriculture “it’s possible to make new soils consciously and rapidly,” says ecologist and filmmaker John D Liu, who has been documenting the incredible revitalization of the Loess Plateau region in China for 20 years. The region was one of the most eroded places on Earth; revitalization efforts begun in 1995 are already showing results. “We can see a return of trees at the tops of the mountains and on the steep slopes, vast orchards on terraced hillsides and increased production of annual crops in the bottom land,” Liu says.
Ecological agricultural practices have the multiple benefits of not only increasing productivity, but also reducing erosion and fostering resilience to droughts and flooding. They increase soil carbon content by taking the greenhouse gas out of the skies and storing it in the ground. But despite the proven benefits of agroecology, chemical methods are being pushed around the globe. In some African countries more than half of the agricultural budgets are going to synthetic fertilizer subsidies.
Having just returned from Amsterdam where I participated in an international celebration of soils with, I’m heartened by the movement underway to value this priceless resource. Maybe in the not-too-distant future, school kids across this country will have a real appreciation for soil – and not mind a little of it clinging to their vegetables.
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