Crop Rotation Generates Profits without Pollution (or, What Agribusiness Doesn’t Want You to Know)

October 11, 2012 | 12:56 pm
Karen Perry Stillerman
Deputy Director

UPDATE: March 18, 2013, 3:15 pm: See bottom of post for an update on coverage of this story.

Big Ag has worked hard for decades to instill a belief—in farmers, policymakers, and the public—that its chemical-intensive industrial farming methods are more productive than low-input methods, and more profitable for farmers. In recent years, study after study has cast doubt on this view, and now a team of government and university researchers has published perhaps the most compelling data yet showing that more sustainable farming systems can achieve similar or greater yields and profits, despite steep reductions in chemical inputs.

The so-called Marsden Farm study is a large-scale, long-term experiment conducted by researchers from the U.S. Department of Agriculture (USDA), the University of Minnesota, and Iowa State University. So no, these aren’t California hippies or east coast elites. These folks know the dominant agricultural landscape of the Midwest—corn and soybeans. But they also want to better understand how systems that incorporate other crops, and even livestock, compare when performing head-to-head.

Keeping it simple (or not)

Over a period of nine years (2003-2011) on the Marsden Farm at Iowa State, the researchers replicated the conventional Midwestern farming system—a highly simplified rotation of corn and soybeans on the same fields on a two-year cycle, with copious additions of chemical fertilizers and herbicides. Alongside it, they grew two multi-crop alternatives: a 3-year rotation incorporating another grain (triticale or oats) plus a red clover cover crop, and a 4-year rotation that added alfalfa (a key livestock feed) into the mix.

Aerial view of the Marsden Farm plots. (m=corn/maize, s=soybeans, g=small grain, a=alfalfa)

The researchers compared these systems on productivity, profitability, and environmental health, and their findings, published this week in the journal PLOS One, are striking. In particular:

  • The more complex systems enhanced yields and profits. Over the course of the experiment, average corn yields were 4 percent higher, and average soybean yields 9 percent higher, in the longer rotations compared to the conventional system. Furthermore, the researchers found that the longer rotations were just as profitable as corn-soy alone.
  • Conventional corn-soy rotations require more chemical fertilizer and energy inputs. Fertilizer use was higher in the 2-year rotation than in the more complex systems. And this difference increased over the course of the experiment, with the 3- and 4-year rotations requiring even less of these inputs in the later years, probably due to cumulative improvements in soil quality over time.
  • Diversification controls weeds while slashing herbicide applications. The longer rotations reduced herbicide use by a whopping 88 percent compared with the conventional system, with little difference in weediness. Furthermore, the ecotoxicity of the systems (as measured by the freshwater toxicity of the herbicides used) was 200 times less in the longer rotations. Given everything we know about weed resistance and rising herbicide use on U.S. farms (including this new estimate), strategies that help farmers control weeds with less herbicide are critically needed.
  • Longer rotations substitute labor for other inputs. Some people will no doubt see this as a strike against crop diversification. But with energy costs on the rise and unemployment stuck just under 8 percent, that’s starting to seem like seriously fuzzy logic.

Improving farming…when the cows come home?

In addition to incorporating more crops, the longer rotations at the Marsden Farm also brought animals back into the mix. The authors note that:

Reintegration of crop and livestock production, as represented by the forage legumes and manure applications present in the more diverse systems, is not simply another aspect of cropping system diversification. Instead, it embodies an important principle in sustainable agriculture: system boundaries should be drawn to minimize externalities.

In other words, livestock will produce manure wherever they are raised. In a CAFO, manure is likely to become a waste product and water pollutant. But if, as in the longer Marsden rotations, feed grains and alfalfa are grown for livestock raised on-site or nearby, their manure in turn becomes an asset, fertilizing the crops, improving soil quality, and reducing the fossil fuel needed to transport grain and manufacture synthetic fertilizers.

The researchers conclude:

Substantial improvements in the environmental sustainability of agriculture are achievable now, without sacrificing food production or farmer livelihoods. When agrichemical inputs are completely eliminated, yield gaps may exist between conventional and alternative systems. However, such yield gaps may be overcome through the strategic application of very low inputs of agrichemicals in the context of more diverse cropping systems. Although maize is grown less frequently in the 3-yr and 4-yr rotations than in the 2-yr rotation, this will not compromise the ability of such systems to contribute to the global food supply, given the relatively low contribution of maize and soybean production to direct human consumption and the ability of livestock to consume small grains and forages. Through a balanced portfolio approach to agricultural sustainability, cropping system performance can be optimized in multiple dimensions, including food and biomass production, profit, energy use, pest management, and environmental impacts.

Corporate interest vs. public good

Now, you can bet that Monsanto (or Syngenta, or Cargill) would never pursue a study like this one. I mean, why would they? There’s very little for big corporations to sell to farmers who are engaged in low-input agriculture. In fact, just the opposite—the more farmers are convinced they can’t be profitable without pricey inputs, the better the companies’ bottom lines will look.

Even when it just isn’t true.

And that brings me to another interesting finding out of the USDA last month. A trio of researchers at the agency’s Economic Research Service (ERS) documented the extent to which private companies hold the reins when it comes to research on food and agriculture. According to the ERS brief, the private sector performs 53 percent of total food and ag research in the U.S. And the long-term trend has been toward greater corporate-funded R&D.

Of course, it’s only natural that companies would invest in areas that pay off in private return rather than broader social good. That’s what corporations do. They also—as you would expect—lobby for policies that serve to increase those purely private returns on their research dollars.

But the ERS economists go on to cheerlead public research as “complementary” to all this private sector R&D. Whereas I would argue that current levels of public investment are inadequate—pitifully small, really—to address the enormous agricultural challenges our society faces, which the private sector has no interest or incentive to deal with.

Every now and then we get a Marsden study that refutes Big Ag’s dominant storyline. But mostly farmers and policymakers just hear what the companies want them to hear.

So when the Marsden researchers say in their groundbreaking paper that  “there has been an interest in reintegrating crop and livestock systems as a strategy for reducing reliance on fossil fuels, minimizing the use of increasingly expensive fertilizers, and limiting water pollution by nutrients, pathogens, and antibiotics,” it’s important to remember who has that interest.

And who doesn’t.

UPDATE: March 18, 2013, 3:15 pm:

Since I wrote this post last fall, the story of Iowa State University’s Marsden Farm study has been covered by the New York TimesWired magazine, Iowa Public Radio, and farm press outlets such as this one, and shared widely on social media, as with this tweet:


As a result of all this publicity, I am told the peer-reviewed article—published by the open-access journal PLOS ONE—has been viewed or downloaded more than 21,300 times.

(To put that in perspective, according to this usage table, PLOS ONE published 5,250 research articles on a variety of scientific topics in 2012, and their average lifetime usage—combined page views and downloads—was just 900.)

So it is curious that Iowa State’s Office of University Relations, which handles communications for the university and typically (and appropriately) takes every opportunity to trumpet the knowledge, successes, and contributions of its researchers to the general public, hasn’t done more to shine a light on these groundbreaking findings. Yes, there’s a pretty wonky article about it buried in the university’s ag extension bulletin. But as a premier taxpayer-funded university in the Midwest, ISU has a responsibility to use the tools at its disposal—a press office that can reach mainstream media, along with the university’s Twitter feed and Facebook page—to tell the average person in farm country and beyond about this research and how it could revolutionize farming.

Why wouldn’t they do that?

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