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Crop Diversity Payday

When crop prices are slumping, it isn’t easy to change the norm. Growing corn and soybeans is what many of you know and do all too well. But look closely to see the cracks forming in the corn-soybean foundation that dominates the Midwest. 

  • Low crop prices that threaten the economic viability of a monoculture crop sequence.
  • Herbicide-resistant weeds that can be hard to kill in this rotation.
  • Slumping soil organic matter that can impair the soil’s ability to function as a system.

Farmers of a few generations ago grew a number of crops in addition to corn and soybeans. These may have included flax, clover, oats, or buckwheat, and these crops may have been harvested for grain, fed to livestock, or plowed under for green manure. 

Great-Grandpa was onto something. He didn’t have a lot of the agronomic problems that plague today’s farmers. Over time, however, farmers became less diversified, and focused on a few cash crops, says Dwayne Beck, who heads the Dakota Lakes Research Farm near Pierre, South Dakota. Government programs, the availability of commercial fertilizers, and improved machinery helped hasten that movement.

“Farmers 150 years ago, used essentially zero fossil fuels,” Beck says. “Now we’ve gotten pretty good at taking fossil fuels and making stuff, then shipping it out. We’re mining energy. We fail to look at soil as a resource. It’s just there, a vessel that we take stuff out of.” 

Diversifying crop rotations can help make you more sustainable and add profit potential, too. Take the example of Dan Forgey, agronomy manager at Cronin Farms, near Gettysburg, South Dakota. 

In the 1970s and 1980s, the farm averaged 30-bushel-per-acre winter and spring wheat, and 50-bushel-per-acre corn. They fallowed some land and worked the ground first with a sweep plow, and they later added a rodweeder. By 1991, the farm included 5,150 acres and employed four people. A quarter of their acres lay in fallow each year. “We thought it was the best we could do. We were good farmers!” Forgey says.

At Beck’s urging, they switched from minimum-tillage to no-till and kept the same rotation: spring wheat, winter wheat, corn, and sunflowers. New problems emerged, though. “Cheatgrass figured out our crop rotation, so we changed it,” Forgey says. “We put three years of broadleaves into our crop rotation – rather than just two years – and got cheat under control.”

That simple move spurred change on Cronin Farms. 

“I’ll fix an agronomic problem with crop rotation rather than use a chemical. It took me a while to learn that I needed to work with Mother Nature rather than against her,” Forgey says.

“If you have an agronomic problem, you have given Mother Nature an opportunity,” Beck adds. “With herbicide-resistant crops, you might have thought you didn’t have to worry about crop rotation, and soon you had resistant weeds.”

Drawbacks galore

There are plenty of reasons to not diversify the crop rotation. Having to change equipment to plant and harvest a new crop, plus find a market for them are two drawbacks. Farming is hard enough without diversifying enterprises. 

Adding a crop like wheat, for example, is particularly unappealing due to the commodity’s record-low prices (adjusted for parity).

For the soil

However, Forgey believes there is opportunity, too. To date, his Cronin Farms operation has adopted more than 13 crop rotations, none of which is fixed. This includes more than 20 crops, including teff, field peas, lentils, forage sorghum, sunflowers, radishes, millet, sudan, field peas, and more. “I like the challenge of growing different crops, but I love the diversity they give the soil,” he continues.

Furthermore, he has added cattle to the operation to consume some of those crops and to diversify the farm’s income stream.

You may not choose to incorporate the array of crops that Cronin Farms does. However, tweaking the crop rotation just a little bit breaks up disease and pest cycles. 

“That’s an effect that’s really visible and easy to see. The impacts are there. People have seen those effects for centuries,” says Lisa Tiemann, assistant professor of soil biology at Michigan State University. 

Studies at the University of Wisconsin show a 19% yield bump for corn and soybeans when grown in a rotation rather than in a continuous system. The reason has not been defined, but it is likely due, in part, to reduced disease and insect pressure.

Below the surface

Tiemann, meanwhile, believes yield increases can also be attributed to what happens in the soil. 

She and her colleagues have studied more than 300 crop-rotation comparisons involving single-crop systems, two-crop systems, and more diverse systems.

Adding one cash crop to a monoculture increases by 21% soil microbial biomass, or all the microorganisms living in the soil. 

Further, organic carbon and organic nitrogen concentration tend to increase dramatically in soils on which diverse crops are planted, as opposed to a monoculture. In a crop rotation, Tiemann sees increased stability of larger soil aggregates, which indicates the formation and accumulation of soil organic matter (SOM). 

Add a cover crop to the system and soil organic matter accrues 15 times faster than rotations without a cover crop, she adds. 

It’s hard to visualize diversity within the soil, and Tiemann reckons it may be a few years before you see financial gain due to crop rotation. She points out, however, that you can reverse the decline in SOM by incorporating crop diversity. 

“Whenever soil is tilled, you lose organic matter. If you want to start thinking about building it, do it now,” she says. 

Building SOM by 1% has real benefits. In 1 acre, 10,000 pounds of soil carbon – and 1,000 pounds more inorganic nitrogen – are added. Also, water-holding capacity in those soils increases, up to ¾ inch more per foot. 

South Dakota’s Forgey notes that SOM levels average 5.1% in native grass near Gettysburg. In 2001, soils that had been farmed conventionally for years had an average SOM of 2.8%. By 2012, SOM in those same soils increased to 4.1%. 

“You may not see an economic advantage right now, but think about the future and the legacy you’ll leave behind,” Tiemann says.

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