Stephen Leahy, International Environmental Journalist

By Stephen Leahy

(Published in the Earth Island Journal Spring 2008)

30% of farmland can no longer grow food

A harsh winter wind blew last night, and this morning the thin snow cover has turned into a rich chocolate brown. The dirt covering the snow comes from cornfields near my home that were ploughed following the harvest, a common practice in southern Ontario and in the corn-growing regions of the US Midwest.

A handful of this dirty snow melts quickly, leaving a thin, fine-grained wet mess. It doesn’t look like much, but the mucky sludge in my hand is the prerequisite for life on the planet.

“We are overlooking soil as the foundation of all life on Earth,” says Andres Arnalds, assistant director of the Icelandic Soil Conservation Service. Arnalds is an eloquent spokesperson for the unheralded emergency of soil erosion, a problem that is reducing global food production and water availability, and is responsible for an estimated 30 percent of the greenhouse gases emissions. “Land degradation and desertification may be regarded as the silent crisis of the world, a genuine threat to the future of humankind.”

Arnalds is dead serious when he calls soil erosion a crisis. Each year, some 38,000 square miles of land become severely degraded or turn into desert. About five billion acres of arable land have been stripped of their precious layer of topsoil and been abandoned since the first wheat and barley fields were planted 10,000 years ago. In the past 40 years alone, 30 percent of the planet’s arable land has become unproductive due to erosion, mainly in Asia and Africa. At current erosion rates, soils are being depleted faster than they are replenished, and nearly all of the remaining 11 billion acres of cropland and grazing land suffer from some degree of erosion.

Most of this erosion is simply due to plowing, removal of crop residues after harvest, and overgrazing, which leaves soil naked and vulnerable to wind and rain. It is akin to tire wear on your car — a gradual, unobserved process that has potentially catastrophic consequences if ignored for too long.

Arnalds has seen our perilous future crisis by looking into the past. Eleven hundred years ago, the first Icelandic settlers came to a cold island mostly covered by forests and lush meadows, and blessed with deep volcanic soils. In a pattern repeated around the world, settlers cleared the forests and put too many animals on the meadows, until 96 percent of the forest was gone and half the grasslands destroyed. By the 1800s, Iceland had become Europe’s largest desert; the people starved, and the once prosperous country became one of the world’s poorest. “Once soil is gone, you can’t get it back,” Arnalds says. “It’s a non-renewable resource.”

Nickel and Dimed to Death

No one knows how much food-producing land will be left by 2050, when another three billion people are expected to join the current global population of 6.5 billion. What we do know is that right now, 99 percent of human food calories come from the land. Global food production has kept pace with population growth thus far thanks chiefly to the extensive use of chemical fertilizers. But food production per acre of land is starting to decline, primarily due to loss of productive land and water shortages. The latter is often the result of soil erosion because soil and vegetation act as a sponge that holds and gradually releases water. And that soil erosion, in turn, is exacerbated by chemical farming practices that over time break down soil structure.

Add to these challenges climate change’s impact on soil erosion and the competition between growing food and producing biofuels, and it’s frightening to consider the challenge of feeding nine billion people when nearly one billion go hungry right now. Arnalds summarizes the challenge: More food will have to be produced within the next 50 years than during the last 10,000 years combined. “Securing food in many places will become a crisis of rapidly growing proportions.”

Erosion largely goes unnoticed by farmers as it “nickels and dimes you to death,” says David Pimentel, an ecologist at Cornell University who has conducted extensive research on the subject. Even if there were no humans on the planet, soils would still erode. The soil formation from the weathering of rock and the breakdown of plants, however, would be faster than the erosion rate; it takes roughly 500 years to create one inch of soil. Once humans remove natural vegetation, soil is exposed to raindrops that easily dislodge it, washing soil particles into creeks, streams, rivers, and eventually into the ocean. One rainstorm will wash away .04 inches of soil. This may not seem like much, but over one acre of land that fraction of an inch adds up to tons of topsoil.

Wind also disrupts soil, and can transport dust huge distances. Dry and windy conditions blew nearly two inches of topsoil off Kansas farmlands during the winter of 1995–96. Contrary to common belief, the topsoil loss in Kansas didn’t end up being neatly deposited on farms in neighboring states. More than 60 percent ended up clogging ditches, streams, rivers, and lakes. That makes waterways more prone to flooding (further exacerbating erosion) and contaminates them with fertilizer and pesticide residues, Pimentel says.

Every rainy day or windy night steals a thin layer of soil from any exposed piece of ground until there is little left but sand and rock. “Iowa has some of the best and deepest soils in the world,” Pimentel says, “and they’ve lost nearly 50 percent in the last hundred years.”

Erosion’s potential threat to humanity remains largely ignored by the world community. When soil experts from around the world met in Selfoss, Iceland in August 2007, they concluded that an international treaty is needed to spur countries into taking action to protect their soils. The soil scientists proposed that, at the very least, soil ought to have its own year — “The International Year of Land Care” — to focus the world’s attention on soil stewardship.

But hold on a second. While politicians, CEOs, and autoworkers might not think much about soil, surely farmers, whose very existence depends on soil, don’t need a bunch of international lawyers and bureaucrats at the United Nations to tell them to protect their lands. After all, controlling erosion isn’t rocket science. By now it’s well known that agricultural practices such as protecting soil with cover crops when the land is not growing edible crops, keeping post-harvest plant residues on the land, and reducing overgrazing and forest clearance are some of the ways to protect soils.

“Farmers know their success depends on the soil, but they often have more immediate needs, such as feeding their families, paying school fees, or fleeing corrupt governments,” says Michael Stocking of the University of East Anglia in Britain, and one of the leading experts on agriculture in tropical countries. Most farmers face so many short-term challenges that it is difficult to invest in the long-term protection of the soil. Social and economic pressures force many farmers to “mine the soil” until the land is completely denuded and is turned into “badlands,” Stocking says.

Such badlands can be found in every country in the world, and are easy to spot. A more worrisome trend is the hidden danger of losing soil fertility on lands that appear healthy. “Fertility loss on good soils has a much bigger impact than further degradation of badlands,” Stocking says.

To read the rest of the article see Peak Soil