Dust storm approaching Stratford, Texas, in the 1930s. Drought combined with years of plowing under crop residue, leaving the surface exposed to wind, resulted in gigantic dust storms that devastated the Plains states. Photo credit: NOAA Photo Library, Historic NWS collection

Throughout history, civilizations expanded as they sought new soil to feed their populations, then ultimately fell as they wore out or lost the dirt they depended upon. When that happened, people moved on to fertile new ground and formed new civilizations.

According to David Montgomery, a University of Washington professor of earth and space sciences, that process is being repeated today, but the results could be far more disastrous for humans because there are very few places left with fertile soil to feed large populations, and farming practices still trigger large losses of rich dirt.

“We’re doing the same things today that past societies have done, and at the same rate,” says Montgomery. In essence, we are slowly removing our planet’s life-giving skin.

“It only takes one good rainstorm when the soil is bare to lose a century’s worth of dirt.”

In the past, as soil was depleted in a particular region – the American South during the height of tobacco plantations, for example, or the Great Plains during the Dust Bowl of the 1930s – people moved to new areas that could support their crops. But Montgomery argues that their primary farming method – plowing under any crop residue and leaving the surface exposed to wind and water erosion for long periods – was a major cause of the conditions that drove them from the land.

Now, with more than six billion people on the planet, the option to move on no longer exists.

“We’re farming about as much land as we can on a sustainable basis, but the world’s population is still growing. We have to learn to farm without losing the soil.”

He advocates a wholesale change in farming practices, moving to no-till agriculture, a method that eliminates plowing and leaves crop stubble in the field to be disked. Currently only about five percent of the world’s farmers engage in no-till agriculture, the vast majority of them in the United States and Latin America.

Montgomery is the author of Dirt: The Erosion of Civilizations, a popular review of scientific literature on soil and farming practices.