Visualizing Iowa's topsoil loss

IDOT Adair.jpeg

These pillars—located outside a rest area off Highway 80 in Adair County, Iowa—represent the topsoil Iowa has lost since large-scale farming began 150 years ago. In the 19th century, Iowa had 14-16 inches of topsoil. Today, it has just 6-8 inches of the stuff, and more is being lost all the time. The irony: The very farms that are depleting the topsoil desperately need it, too. (Image: RDG)


  1. So where are they losing it? My gardening areas are built up every year. I got to take soil out or it overruns the confined space. It’s not that hard, just dump your organic junk in the fields and when you rotate your crops, till it under. Horse manure, cow manure, stalks, weeds, everything you clean out of a horse barn, lawn cuttings, sawdust…didn’t these guys learn anything with the dustbowls and mandatory crop rotations? Most likely, they figure they don’t have to worry about it since the government has gotten them used to subsidies. Just stick your hand out and beg.

  2. Topsoil loss is not an inevitability- but it IS an inevitability if you just keep using the same farming methods.

    Farmers who convert to no-till agriculture reduce the rate of erosion, but no-till still can be erosive.

    Allan Savory’s system of Holistic Management incorporates a multidisciplinary approach to agriculture, and BUILDS new topsoil. The “accepted wisdom” of topsoil formation is that it is formed very slowly- on the order of cm/ thousand years. Holistic Management can form soil a thousand times faster- cm/year.

    Other topsoil formation concepts to look at- Keyline Plowing, Darren Doherty, permaculture.

  3. Topsoil erosion and aquifer depletion (I’m looking at you Ogallala!) are two incredibly important issues that are really not getting any attention.

    The long term impact that both of these issues could have on global food supply is enormous, yet it gets barely a peep of mainstream attention.

    1. Waterways. It gets carried away by wind and rainwater, until it eventually reaches the ocean.

      If you want to know how bad erosion can get, and how a responsible society deals with it, look at Iceland. Iceland’s soil was very, very rich when the vikings first got there- it had been building up slowly since the last ice age. But the rate of loss turned out to be much greater, the the rate of increase much lower, than in Scandinavian countries. So, after just a few centuries, traditional farming methods had some very serious consequences.

  4. Run-off. It ends up in the Mississippi river and thence to the Gulf. Ever seen a satellite photo of the Mississippi Delta and the green-and-brown plume where it enters the Gulf? That’s the sediment plume from the Mississippi river.

  5. one of many reasons ethanol is such a clever idea! in answer to where it all ends up: a lot of it simply turns into carbon dioxide and adds to the greenhouse gas problem (topsoil is rich in carbon, something depleted by intensive agriculture). also, much of it ends up as muck on the bottom of the mississippi, gumming up locks and dams.

    1. No. The topsoil (represented by the dark band in mid-column) is at 1:1 scale – pretend the top of those bands is at ground level.

      The bits above the band are meant to represent the native grass flora (much of it 6-8 feet tall), whilst that below is meant to show the different layers of the subsoil.

      Traveling this stretch of I-80 frequently, I have occasion to stop at this rest stop from time to time, and this sculpture never fails to depress me.

      1. I’ve seen photos of buildings sitting on 10′ hills that used to be ground level, where several feet of soil was picked up and carried off in the dust bowl. Am I misunderstanding that, or was that somewhere other than Iowa?

  6. There’s even more irony here. The topsoil (which naturally erodes and is replaced, but is now lost much faster) is heading down Big Muddy (Mississippi River) to the Delta. Presently however, instead the sediment load is sent straight out, off the deep end of the Gulf, for purposes of clear shipping channel. Result: coastal marshes are starved of needed sediment (one reason they are disappearing), and the Dead Zone is smothered.

    The good news is, we have the ability to slow topsoil erosion, and even reverse it. Current ag policy will never get us there, though.

  7. When there is an inch left they will start arguing about who is causing it and if it’s natural or man made and still nothing will be done.

  8. I realize a lot of agriculture near the river contributes to the erosion, but what about all the goings-on well away from any major waterways? Surely run-off can’t span hundreds of miles of open, flat ground, can it? The location of this particular rest area, for example, is nowhere near a major river; it’s west of Des Moines, about a third of the way to Omaha.

    Are the crops themselves slowly leeching the elements out of the soil and converting them to biomass?

    1. Problem is, Iowa isn’t flat. It is carved up by hundreds of tributaries that end up in the Mississippi and Missouri rivers.

      1. True, Grant, about the many streams. Also, soil is lost by being literally blown away.

        Pinehead: As for the minerals, much of the biomass of a crop is carbohydrate (like cellulose), so relatively little mass/volume of the soil is removed and stored in the plant tissues.

    2. Exposed topsoil can also be blown away by the wind.

      The Land Institute is trying to solve this very problem by breeding perennial wheat, sorghum, and sunflower. The plants’ root systems could remain in place while their produce could be harvested seasonally – reducing erosion while still maintaining an agriculture industry.

      Their website is down, but here’s a link to the Wikipedia article:

  9. We are using up the topsoil because the plants take up minerals when they grow. You can’t keep taking, taking from the soil and not giving back. Organic matter needs to be put back. It was good when we spread cow manure on the fields.

  10. i’ve see the one just over the Minnesota-Iowa border on the 35W freeway.i thought it was sort of brave of them to spotlight the loss of the soil rather than just how wonderful farming is.

  11. I don’t think that this is irony, I think it’s a tautology. Irony would be more like “A system designed to preserve topsoil ended up eroding it more quickly than if it had been left alone.” But this is a tautology because it is just saying “Farmers use topsoil so they need topsoil.”

  12. Somebody told me it was frightening how much topsoil we are losing each year, but I told that story around the campfire and nobody got scared.

  13. Wendell Berry wrote, “Industrialized agriculture has taken a solution and neatly divided it into two problems, 1) monoculture farms that need fertility and, 2) confined area feed lots with excess manure.” The solution he’s speaking of is the farm where animals and plants are grown near each other, on a smaller, more natural and manageable scale.

  14. I’ve read that the great plains had a thick mat of grass that trapped the topsoil. One book reported (not exact words) that when it was first plowed it sounded like a canvas tarp being ripped.

  15. Although plants are composed mostly of carbohydrates, they get this from the organic material in the soil … material Iowa soils are seriously lacking. The material decomposes and, if not replenished, ceases to hold the mineral soil. It blows away, it erodes.

    Don’t know how we are going to accomplish this short of Armageddon, but all the plant material removed from the land … including the uneaten portions and, ultimately, the manure from man and beast, needs to come back and be re-incorporated into the soil. We live in a finite biosphere. This circle needs to be closed. Nothing biodegradable can be allowed to escape forever.

    As noted earlier, alcohol for use as fuel needs to stop. Not moderate. Stop.

    The fertility can return … if we have the will to return it.

    Probably we don’t.

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