The Transition To Crop Rotation: How Do We Get There?

, sr. scientist emeritus, Food & Environment | October 30, 2012, 10:09 am EDT
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Recently, we have seen a flurry of stories about studies done on Iowa State University’s Marsden Farm demonstrating the power of crop rotation as an engine of modern sustainable agriculture. The study documented high yields and handsome profits on farming plots employing long crop rotations: three-or four-year rather than the usual two-year corn-soy rotations. In addition to high yields and high profits, the long rotations controlled weeds with only sparing use of herbicides and maintained productivity without excessive use of chemical fertilizers.

Fields in Kansas. The different patterns and colors come from different irrigation methods and crop rotation. Source: Wyoming_Jackrabbit via Flickr.

Unlike the use of herbicide-tolerant or Bt crops, which inevitably elicit resistant weeds and insects over time, long rotations provide durable benefits: they will continue to dampen pest levels, reduce input costs, and produce high yields far into the future. In short, the systems are sustainable.

In theory, this is great news. But the sad truth is that three or four-year rotations are the exception rather than the rule in American agriculture. Many farmers don’t even employ the two-year corn and soybean rotation. They just plant continuous corn year after year after year.

Why don’t farmers rotate crops?

If farmers who employ long crop rotations can expect to enjoy higher yields and make more money, why aren’t more of them doing so?

Why don’t farmers add oats, alfalfa, or triticale to their traditional mix of corn and soy?

One answer is that many farmers already enjoy record profits and change is hard. But the environmental and health harms of the current system are increasingly unacceptable to non-farm sectors of society, who are beginning to demand change.

The power of a rotation-based agriculture has been appreciated for a long time. Dick and Sharon Thompson, the pioneering farmers acknowledged as an inspiration by Matt Liebman, one of the Marsden study’s principal investigators, were active in the 1970s and 80s, a time of ferment around the notion of sustainable agriculture. What has happened since then?

Over these last three decades at least two forms of innovative agriculture have flowered. One—the modern organic movement—is centered on the relationship between farmers and food consumers and focuses on trustworthy food labels, near absolute prohibitions of synthetic inputs like pesticides and chemical fertilizers, and the possibility of premium prices for farmers who meet stringent criteria. The other—sustainable agriculture—focuses more broadly on agriculture and features “as necessary” use of chemical inputs in farm systems and practical solutions appealing to farmers and ranchers. The National Campaign for Sustainable Agriculture and its constituent organizations are premier exponents of the sustainable agriculture vision.

The organic and sustainable movements overlap in many ways, most fundamentally their common commitment to ecosystem services as the basis for successful agriculture. And both have enjoyed substantial success. (See here for recent info on the success of organic food.)

But conventional agriculture has largely resisted transition to sustainability. Why? The Marsden Farm studies provides fresh evidence of strong reasons for conventional farmers to move to sustainable systems—increased profits, high yields, and fertile land to pass on to their children.

I am honestly puzzled. What is standing in the way?

Farmers don’t act alone

I’ll take a stab at an answer here, but I would like to know what you think too.

Recently Secretary of Agriculture Vilsack denied accusations that he had suppressed the Marsden Farm study. I’m sure he’s telling the truth. The USDA supported the study financially and probably wishes the sustainable approach had more traction than it does. But in discussing the issue, the Secretary pointed to the real problem. He said “[W]e [the USDA] support all forms of agriculture production, but ultimately it’s up to the producer,” implying that the current situation is a result of individual farmer choice.

That’s where I think the Secretary missed the mark. Farmers don’t act alone. They make decisions about what crops to plant in a landscape molded by others. The terrain of the landscape makes some decisions easy for farmers and stands in the way of others. That landscape includes financial subsidies, research agendas, crop insurance and farmer education. Currently, the policy terrain directs agriculture towards simple, highly productive systems dependent on expensive chemical inputs.

We need to point agriculture in a different direction, toward systems that protect the environment without sacrificing profitability. Then we need to start fashioning a new set of policy tools—new subsidies, new kinds of crop insurance, new research agendas—all aligned behind that goal. Under this scenario, ecosystem services produced by crop and allied practices would become the organizing principle of agriculture and the bulk of American farmers would find implementation of crop rotation, cover crops, and other new practices feasible, even comfortable.

Your ideas?

A new policy landscape oriented toward crop rotation and sustainability. That’s my idea.

What do you think it would take for conventional U.S. farmers to adopt 3- to 4-year crop rotations?

Let me hear from you.


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  • Emily,

    Thanks for you comment.

    I understand fully that farmers need choices that enable them to prosper financially, feed their families and send their children to college.

    I think our collective task is to devise an agriculture system that produces ample food AND protects the environment AND secures good livelihoods for farmers.

    We have many ways of achieving multiple goals in agriculture if we are willing to adopt new research agendas, fashion better subsidy policies, and provide farmers with better insurance tools.

    It is an ambitious agenda that is based on a sophisticated understanding of science that looks forward not back.


  • Bill

    The market signals what is needed, and farmers plan what to grow next season based on market signals the fall and winter before the next crop year. There is a limited demand for oats, hay and tritacale, as well as other minor crops. We use a three to four year rotation because we grow pumpkins which can not be planted back to the same acreage for that long due to disease problems that would occur on a shorter crop rotation.

    • Thanks, Bill.

      I agree that market signals (expected crop prices) are important in making short term decisions about what to grow. Right now, corn is selling at a high price because there are many uses for corn (feed, sweetner, and ethanol) and corn is in short supply because of the drought. So corn is good choice for farmers.

      But that begs the question why are there so many uses for corn. Part of the reason is that research funds have been funneled into corn for decades,resulting in the multiplicity of uses that keeps demand for high.

      Other crops have not recieved that kind of dedicated research and have fewer high value uses. So a good place to start is a research agenda that gives the farmers of the future more choices of profitable crops.

      Structural changes in animal agriculture might also increase the value of non-corn crops. Some of this is already happening in response to high corn prices.

      There are lots of ways of increasing the attractiveness of a wider array of crops to farmers. But first we need realize the value of a system that incorporates crop rotation. Then we can devise strategy for making it happen.


  • Emily

    Oats and hay were pretty good crops once upon a time. I remember my grandfather telling us how his grandfather used to feed oats to the work horses on the farm. Do you recommend getting rid of trucks and tractors and going back to horses? Maybe modern farmers are reluctant to grow obsolete crops because there is no place to sell them. Farmers have families, they put kids through college so they probably need to produce what markets demand.