Everything in Agriculture is a Trade-Off

Tillage or herbicides. Both come with different sets of trade offs.

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screen-shot-2016-10-30-at-5-42-59-pmFAFDL CONTRIBUTOR: Andrew Kniss, Associate Professor, Weed Biology & Ecology University of Wyoming | Follow him on Twitter: @WyoWeeds

This is an older essay that previously appeared on Control Freaks, but it’s an evergreen topic so we thought it deserved another look.  It appears here by permission of the author.

The idea of trade-offs is familiar to everyone. None of us have unlimited money, time, or energy. We make decisions every single day about how to spend our money, our time, and our energy. Do I buy the red shirt or the blue shirt? Do I watch the football game or go to the concert? Should I ride my bike to work or hope I can find a good parking place? Do I call a plumber or try and fix the sink myself? Do I want the chili or the pasta? All of these decisions have costs (and hopefully benefits); some financial, some social — and some digestive.

Similarly, farmers face production decisions almost every day. Farming is complex. Just about every decision made on a farm will send ripple effects throughout the entire system; these decisions will influence the cost/benefit ratio of many future decisions. This complexity makes it difficult to make rapid changes, and is a major reason why many farmers tend to be pretty conservative in their farming decisions. Even if a farmer wants to try something new (a new technology, or a new crop, for example), that option may be precluded by decisions that were made last year, or even many years ago.

Weeds are a fact of life for farmers around the world, and weeds influence many of the decisions farmers make, either directly or indirectly. If we simply ignored weeds, we could expect world food production to decline by 20 to 40 percent. Sure, a farmer could decide to do nothing about the weeds. That would be a trade-off; letting the weeds grow will reduce crop yields. It is almost always going to be better to do something to manage weeds than to lose a huge percentage of the crop. But now the farmer must decide what to do to control the weeds. Remove them by hand? Till them? Burn them? Alter the crop planting date to disfavor the weeds? Rotate crops to help keep the weeds from building up over time? Harvest the crop early to avoid weed seed production? Spray a herbicide? Which herbicide? On every farm I know of, farmers don’t just just choose one of these things, but a combination of several to many practices.

Over the last 30 years, one of the most common choices made by farmers around the world has been to include the herbicide glyphosate (commonly known as Roundup) in their weed management program. That choice has placed glyphosate in the news again. A paper from Charles Benbrook declares that nearly 19 billion pounds of glyphosate have been applied worldwide since 1974, and that it has become “the most widely applied pesticide” in history. It is difficult to argue that the increase in glyphosate use since its discovery has been pretty remarkable. And to be honest, such a dramatic increase in any single herbicide is a somewhat troubling trend.

“Farmers should stop using so much glyphosate.”

A page from a children's book, explaining the decision making process.
“A big decision is easier to make when a person knows what to do. Knowing how to make a big decision involves understanding the decision making process.“

I tend to agree that farmers should stop using so much glyphosate. It is a reasonable request, at least from a big-picture perspective. Such heavy reliance on any single pesticide is probably not a good thing. But let’s zoom in to the farmer perspective. The image below is from a children’s book about how to make decisions. “Knowing how to make decisions involves understanding the decision making process.” There are reasons that farmers use so much glyphosate, and if we are serious about wanting them to change, we need to understand their decision making process. If farmers stopped using glyphosate, weeds wouldn’t just stop growing, so something else must be done to control them. There will be costs to that decision.


Some of the costs of not using glyphosate would be financial. My own research has shown that glyphosate use in conjunction with a glyphosate resistant crop has significantly boosted net economic returns. Removing this option, then, would reduce the economic viability of many farming operations, at least under current farm policy. How would you respond if someone asked you to take a 5 to 20% cut in pay? If we want farmers to make decisions that will negatively impact their own livelihood, then we need to figure out a financial incentive to make that happen. How much are we willing to pay to help farmers reduce their use of this herbicide?

There will be social costs to reducing glyphosate use, too. At least for some crops, farmers would have to miss more of their children’s baseball and softball games because without glyphosate, weed control can become much more complex, labor intensive, and time consuming. The well-being of farmers is a key indicator of agricultural sustainability, and a major tenet of the agroecology movement. One reason many farmers have adopted this herbicide in the first place is because it has bettered their lives. Asking them to reverse those gains shouldn’t be taken lightly.

Data from Carlson et al. (2013).
Glyphosate use in glyphosate-resistant crops has had a dramatic impact on farmers. This figure shows the number of farmers reporting weeds as their worst production issue in the Red River Valley of North Dakota and Minnesota before and after adoption of glyphosate-resistant sugarbeet.



And what about the environmental costs of reducing glyphosate use? One study estimates that using glyphosate herbicide in conjunction with glyphosate-resistant corn and soybean have prevented 41 billion lbs of CO2 from being released into the atmosphere between 1996 to 2013. Adoption of glyphosate-resistant soybean was recently estimated to have increased soil conservation tillage practices by 10, an notill adoption by 20%.These practices help reduce soil erosion, and the many environmental problems associated with soil erosion. Is a reduction in glyphosate worth an increase in erosion and worsening climate change? I acknowledge this trade-off is far too simplistic, as there are ways to mitigate these impacts. But those options have costs also.

Because glyphosate breaks down quickly in the soil, farmers who spray glyphosate can rotate to any other crop the following year (or even in the same year). This makes farm management more flexible, and farmers can respond more easily to market changes. It also allows farmers to more easily diversify their crop rotation, which is one reason glyphosate is commonly used in diversified cropping systems. Conversely, many other herbicides (that would almost certainly increase if glyphosate use ceased) have substantial crop rotation restrictions. For example, spraying atrazine, nicosulfuron, or acetochlor (herbicides commonly used in conventional corn) will prevent planting many crops for 2 cropping seasons because they are so persistent. Soybean herbicide restrictions can be even greater; apraying imazethapyr precludes planting some crops for 40 months after application. If we truly want to encourage crop diversity, then glyphosate use can be a powerful tool in allowing those diverse crop rotations while still managing weeds.

I’m a firm believer that public interest in our food supply is a very good thing. And I also acknowledge that modern agriculture has problems. The public has a right to be engaged in the process of farming, if farming decisions affect public resources. But if we, as a community of food eaters, want large-scale changes in the way our food is grown, yelling and screaming and writing articles and editorials isn’t going to work. If we want to change the way farmers run their business, then we damn-well better engage farmers to find out why they make the decisions they do. We need to understand the trade-offs involved if we are to understand how to best implement the changes we want.

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  • My favorite quote for agriculture, “There are no solutions, only tradeoffs”. -Thomas
    Sowell, only he was not talking about agriculture.