The Lessons We Can Learn from France’s Fertile Soil

Enlarge Image Image Gallery Nearly a week after Hurricane Irene drenched New England with rainfall in late August 2011, the Connecticut River was spewing muddy sediment into Long Island Sound and wrecking the region's farmland just before harvest. Photo Courtesy NASA Goddard Photo and Video

We live on a rock.

Well, not exactly. We are 7 billion to have settled the Earth and made it a place of our own, gathering in cities and vacationing along the seaside. On the neatly stocked shelves of our supermarkets, we find foods sourced from around the world. But for all the sophistication of our modern world, there is still the wild, teeming with exotic life. In lush tropics or barren tundra, millions of species find their homes. But were it not for the thin crust of dirt that coats the surface of our mother rock, there would be none of this.

We may sit as kings on top of a richly diversified food chain, but our existence depends on fertile soil and the hidden life that dwells within it. A vast habitat that evolved inch by inch over time spans scientists qualify as geological, ultimately making life on Earth possible. As Rachel Carson wrote in 1962, “without soil, land plants could not grow, and without plants no animals could survive.”

Soil is not an inert substance, but a vast repertoire of hidden life. Billions of microorganisms are present in just a gram of dirt, while one hectare [roughly 2.5 acres] can hold up to five tons of animal life. Some, like toads, snakes, and ants, are visible to the naked eye, but the vast majority—microbes, fungi, bacteria—are invisible. The dark domain harbors a quarter of all known biodiversity on Earth, and a staggering 80 percent of its biomass. Yet for all of its abundance and proximity, the ground beneath our feet is more unknown than the depths of the ocean floor and the heights of the tropical canopy. Only 10 percent of the 2 million species of bacteria and fungi have been catalogued to date. It’s easy to understand why. There’s something lackluster about worms, fungi, and tiny crustaceans. If I were a biologist, I too would opt for Jane Goodall’s binoculars or Sylvia Earle’s deep-sea gear, over the humble microscope. Dig a little deeper into dirt, though, and you discover an intricate and fascinating universe brimming with activity. Our underground biota may largely be single-celled, but their communities administer the very building-blocks of life, delivering food, inspiring medicine, and purifying water. There may be little intelligent life afoot, but there is a collective intelligence.

Our sustenance depends on a world that is itself ravenous. The primary role of soil organisms is to decompose organic matter that falls to the ground. Worms and bacteria eat away this debris, grinding it up, decomposing it, reducing it to its most basic elements, and thus releasing the essential nutrients needed—nitrogen, potassium, phosphorus, and other minerals—for plants and crops to grow.