The day after Christmas my wife Kathleen and I took a frigid walk along 7-Mile Creek in southwest Iowa and got a firsthand look at a conservation sin that not even December snow could keep under wraps. As the photo below shows, dry corn stalks were marching literally right into a ditch adjacent to the creek. Summer erosion had sent some of the corn stalks, and a whole lot of soil, tumbling into the ditch.
Not all of that soil caving in beneath those stalks will make its way to the Gulf of Mexico; in fact, a lot of it may not even run into the 7-Mile. Technically, that soil is still part of that farm field. But as far as productivity goes, as far as that soil’s ability to grow food and support riparian plant systems, to filter out contaminates that are running off the landscape, it is a lost resource. That’s an important point to keep in mind as a certain prominent scientist tries to promote the idea that eroded soil is simply moved soil and is not really lost. Unfortunately, this fallacy is gaining ground, threatening to stymie solid efforts to promote sustainable use of soil.
In 1999, Stanley Trimble got into a real dirt-kicker of a fight with soil scientists who believe we are losing soil much faster than it can be replaced when he published a paper in the Aug. 20 issue of the journal Science. Based on an analysis of 140 years worth of information about sediment buildup and erosion in the Coon Creek watershed in southwestern Wisconsin, Trimble concluded that we were vastly overestimating the rate of erosion in this country.
In fact, said Trimble, who is a professor of geography at the University of California-Los Angeles, soil scientists and others who were saying we have a soil erosion “crisis” on our hands are alarmists practicing bad science. The scientist took on USDA soil experts, as well as people like David Pimentel of Cornell University, who has long sounded the alarm about soil erosion rates being unsustainable.
“For the last 20 years, we’ve been reading all of these scare stories of how great the erosion is and how it is greater than in the 1930s. There is no physical evidence for this,” Trimble told Science News at the time.
Agriculture should be given credit for bringing the problem under control through the use of such techniques as conservation tillage and contouring slopes, said the scientist in the numerous media reports that covered his paper.
In his paper, Trimble argued that since there was less sediment making its way into Coon Creek, and eventually into the Mississippi, erosion had been decreasing steadily since the 1930s, and was 6 percent of what it was during the Dust Bowl years.
The Trimble paper immediately became the darling of apologists for industrialized, intensive agriculture such as Dennis Avery of the Hudson Institute. Trimble’s assertion that moved soil is not eroded soil provided the basis for many missives against sustainable ag. Perhaps the most bizarre was a 2002 Star Tribune commentary co-authored by former U.S. Senators Rudy Boschwitz and George McGovern. Titled “So-called soil crisis is just a pretense,” it attacked anyone who claimed soil erosion was a problem, and dismissed the sustainable farming movement as one in which its promoters envision “millions of Americans leaving the cities to live and toil on small farms, producing all of their own food and energy.”
Now, almost a decade later, the 1999 Science paper is still being used by anti-sustainable agriculture activists like Avery to justify intensive, industrialized agriculture. Last fall, Avery wrote about Coon Creek and how organic agriculture was responsible for the erosion that occurred in that region during the August floods. And Trimble himself dredged up the study last summer in a lengthy cover story for Regulation, a publication (apparently named by someone with a sense of humor) of the libertarian Cato Institute. In that article, the geographer describes how difficult a time he had getting his Coon Creek work published by scientific journals such as Science.
This is just one example of how mainstream scientific journals are biased against research that announces good news about the environment, argues Trimble in his article. Much like the “liberal” media, scientific journals believe “bad news is good news,” Trimble complains. Trimble uses the Regulation article to take another swipe at “alarmists” like Pimentel. He then goes on to describe how Bjorn Lomborg was supposedly crucified by the “environmental establishment,” including the popular and scientific media, upon publication of his book, The Skeptical Environmentalist: Measuring the Real State of the World.
It’s clear that Trimble is still smarting over the fact that even though his research was embraced by people like Dennis Avery and George McGovern, many soil scientists and farmers still didn’t quite buy wholeheartedly his “the erosion crisis is grossly overblown” argument.
I don’t know if Trimble is right about scientific journals only being interested in bad environmental news. I also don’t know why Science eventually chose to publish his work. I do know that even though the basis of his research—there is less sediment in Coon Creek—is probably sound, the way its being used to influence farm conservation in this country is wrong.
Here’s why: Back in the 1930s, Coon Creek was the first basin in the nation to be targeted for massive soil erosion control efforts. Aldo Leopold, among other conservation pioneers, worked with farmers in Coon Creek to protect the soil and wildlife habitat. It was a great success and it’s not surprising less soil is making its way to waterways in the region.
But, as anyone knows, it’s dangerous to extrapolate results for the whole nation based on what’s happening in one watershed, a watershed that’s been the focus of intense conservation longer than any other in the country. (To be fair, one of Trimble’s on-target criticisms of the USDA’s Natural Resources Conservation Service is that it extrapolated erosion rates for the whole country based on gross over-estimates—estimates stuck in Dust Bowl-era data sets—of how much erosion was occurring in Coon Creek).
And since the late 1990s, a lot of soil-friendly plant cover like hay and pasture has been replaced in Coon Creek with erosive row crops such as corn and soybeans. I’ve visited the area several times recently, and the moderate-sized dairy operations that raise a variety of crops on the contour are fast disappearing.
Respected soil scientists such as the University of Minnesota’s Gyles Randall are expressing alarm that any soil conservation gains we made since the 1930s are being lost as erosive row crops come to dominate the landscape more and more.
Trimble is undoubtedly aware of recent cropping trends—he still does research in the area. In fact, he toured southeast Minnesota’s Whitewater River watershed soon after the August floods to assess soil loss (I’ve put in a call to Professor Trimble to talk about his tour, but haven’t heard back).
But perhaps the biggest flaw in Trimble’s conclusion that soil loss is not a crisis in this country is his claim that less sediment in a waterway means less of an erosion problem. As Pimentel pointed out in 1999, Trimble’s study did not consider what was actually happening on the fields lying in the watershed. “It really is not a good, sound study on agricultural croplands or pasturelands,” Pimental told Science News. Pimentel also told the magazine that while he agrees erosion problems have decreased since the 1930s, “that doesn’t negate the fact that we have erosion and an enormous amount is coming off the land.”
Next time you’re driving in relatively flat farm country before the corn and beans are planted, take note of how the soil at the tops of swells is often much lighter, almost blond colored, when compared to the bottoms. That’s a sign that the topsoil has eroded off the tops and is collecting in the valleys.
People like Trimble argue that even when soil moves around on a field, it isn’t really eroded–it’s just in a different place. But farmers trying to produce good crops off an entire field may have a different take on the situation. I’m reminded of a famous photo in the W.C. Lowdermilk booklet, Conquest of the Land Through Seven Thousand Years. The photo shows 1930s-era French farmers grubbing up eroded soil at the bottom of a hill and loading it into a cart. Lowdermilk explains in the caption that the farmers do this each winter to “help compensate for the downhill movement of soil from erosion.”
I have mixed feelings whenever I view that photo: on the one hand, it shows how highly prized fertile soil can be in farm country. On the other, is hauling soil back up the hill like an agrarian Sisyphus, rather than changing farming practices, really a good use of human and natural resources?
Apparently, people like Trimble, McGovern, Boschwitiz and Avery think so. After all, with modern earth moving equipment, why not just haul that eroded soil back into place? Unfortunately, it’s not as far-fetched as it sounds.
In 2005, USDA-Agricultural Research Service scientists began a five-year experiment near Morris, Minn., to study the feasibility of “reversing soil erosion” by “scalping” soil at the bottom of a hill and using an earth mover to haul it back up to the top. The cost is $800 per acre restored, which may seem cheap as a biofuels-powered farm real estate market sends land prices through the roof. However, so far the scientists have found that where the soil was removed, crops yields were less than half of yields where the soil was hauled to.
“While we have not yet determined the cause of the decreased yield in areas of soil removal, we expect biological processes to be important,” conclude the scientists in a preliminary report.
This kind of research is important because my guess is it will eventually show what those French farmers in Lowdermilk’s time probably eventually figured out: soil is not some sort of inorganic plant stand that you can move from place-to-place with no consideration for the complicated ecology, hydrology and geology that goes into making rich humus. Soil is a creature of its very local environment, not some sort of throw rug you can roll up and toss in the moving van.
Even on a bitter winter day next to a Midwestern creek, soil is a vibrant being festering with life—yet it prefers to execute all that activity while sitting in one place. We move it—either by accident or on purpose—at our own risk.