David R. Montgomery. 2007. Dirt: The Erosion of Civilizations.  Univ. of California Press.

The bedrock of any civilization is food and water.  So you’d think the top priority of nations throughout history would be ensuring farmers were taking good care of the land.

Apparently not — the decline of most civilizations is due in large part to soil degradation and erosion.  Montgomery discusses past civilizations around the globe, which typically last 800 to 2,000 years before ruining their soil.  The usual pattern is: first, only valley bottomland farmed, second, the population increases so much that slopes are farmed, but the soil washes away into the valley.  Finally, the bottom land is even more intensely cultivated, which uses the soil up as it grows thinner and becomes depleted of nutrition from continuous farming. Finally civilization declines and collapses.

The United States is hell bent on topsoil destruction, and always has been. We are on track to destroy our soil faster than any previous civilization thanks to a history of not caring, large monoculture crops, absentee ownership, and mechanization. You can do a lot more harm to soil with a tractor than a horse (compression, deeper tilling leading to more soil that can blow or wash away, greater pollution with pesticides and insecticides that kill off soil biota which help plants fight off pests, etc).  These days there are tractors the equivalent of 1,000 horses or more!

Both George Washington and Thomas Jefferson commented on how poorly American farmers treated their land.  Washington attributed it to ignorance, Jefferson to greed.  Since the principles of good land management were known for hundreds of years previously in Europe, Jefferson’s harsher view is no doubt the correct one.

Tobacco is partly to blame for the very early loss of topsoil in America.  It was a very  lucrative crop, worth about 6 times more than any other crop, plus it could survive the long journey to Europe.  But tobacco crops expose the soil, which washes or blows away in storms.  If storms don’t ruin the soil, tobacco will — it uses 10 times more nitrogen and 30 times more phosphorous than the average food crop.

Tobacco exhausted the land after about five years, so to some extent it was responsible for the continual migration of settlers westward.   Slavery magnified this trend.  Running a farm with multiple, rotating crops requires a great deal of fine-tuned attention.  Slaves worked reluctantly, just hard enough to not get beaten, so it was easiest to train slaves to work in huge mono-culture tobacco (and soil-depleting cotton) fields.

Montgomery makes an interesting case for topsoil being the reason the South started the Civil War.   President Lincoln took the middle ground of allowing slavery where it already existed, rather than banning it as so many wanted, but would not allow slavery to expand to new states.  The largest slave owners made more money selling slaves than growing crops.  If Texas became a slave state, they could double their money, and so the wealthiest slave owners started the Civil war to protect as well as increase their wealth by fighting for the expansion of slavery into new states so they could sell slaves for more money.

To this day, much of the land in the South is still ruined.  Instead of the thick black topsoil described by early settlers, the soil is thin and clayey, and sometimes missing entirely.

Absentee ownership has played a large role in soil exhaustion from the Roman Empire to the present day.  Tenants being paid with a percentage of crops or money are far more concerned with maximizing the harvest than protecting soil fertility.

Mechanization worsens matters.  Like slavery, mechanization requires single crops.  When farms became mechanized, the need for profits to finance the machines becomes more important than the soil.  Increasing debt to pay for machines led to 4 out of 10 farms disappearing between 1933 and 1968.

Large corporate farms are a type of absentee ownership that is particularly likely to foster erosion.  Huge debts need to be paid off on large pieces of farm machinery. The financial pressure to produce as much as possible to earn money to pay off the debt trumps soil conservation.

Mechanized farms are less efficient and profitable than smaller traditional farms because they spend a lot more on equipment, fertilizer, and pesticides.  Larger farms do not bring economies of scale to food production.  Small farms grow 2 to 10 times as much per acre as do large farms.  And because small farms use far less agrichemicals, antibiotics, and fertilizer, they don’t pollute the air, water, and soil as much as large farms do.

Yet the trend continues toward large farms, we’ve gone from 7 million to 2 million farms, with 20% of farms producing almost 90% of food grown in America.

This is because the $10 billion a year in farm subsidies goes mainly go to the largest ten percent of farms, which receive two-thirds of the subsidies. Farm subsidies were meant to support struggling family farms, but now they’re used to actively encourage large farms.

Montgomery points out that “Good public policy would use public funds to encourage soil stewardship—and family farms—instead of encouraging large-scale monoculture”.

Half the fertilizer we dump on the soil is used to replace the soil nutrients lost from topsoil erosion.  “This puts us in the odd position of consuming fossil fuels—geologically one of the rarest and most useful resources ever discovered—to provide a substitute for dirt—the cheapest and most widely available agricultural input imaginable”.

“Enough American farms disappeared beneath concrete to cover Nebraska in the three decades from 1945 to 1975. Each year between 1967 and 1977, urbanization converted almost a million acres of U.S. farmland to nonagricultural uses”.

Within 200 years, America has lost one-third of its topsoil.  At the rate soil was being lost in the 1970’s, it would only take a century to lose the rest of the country’s remaining topsoil.  Yet despite congress being aware of this, the government cut support for agricultural conservation by over half in the 1970’s.  Congress doesn’t get it —they think “why spend taxpayer money to save soil when grain bins are bursting?”

It’s hard to imagine anything worse than allowing the land to lose its topsoil, but there is.  Montgomery writes about how eight major U. S. Companies sold industrial toxic wastes as fertilizer to make money and avoid spending millions to dispose of it properly.  Heavy metals stay in the soil for thousands of years, preventing or stunting plant growth.

In the last chapter, “Life Span of Civilizations”, Montgomery discusses what needs to be done to protect the remaining soil for future generations.  So do buy this book and use the last chapter as a basis for letters of what to do and write your local and national representatives.  Plus alert your favorite environmental groups – agriculture is the most ecologically destructive force on the planet.

Anyone who’s read this far is probably devoted to many causes, but unless your cause is to return to hunting and gathering, I urge you to make preservation of topsoil and reforming agriculture your main cause!

Further reading:

Friedemann, Alice. 2011. Peak Soil: Why Cellulosic and other Biofuels are Not Sustainable and a Threat to America’s National Security.