These days, U.S. corn and soybean farmers are beating the pants off past yields. In 2018, the average national 52.1-bushel-per-acre soybean yield shattered previous yield records. Ditto for 2018 corn yields, which USDA tallied at a record average of 178.9 bushels per acre. 

For now, anyway. Some see some cracks in the system that threaten long-term productivity and sustainability.

“Growing corn and soybeans is a simplified and convenient system,” says Jonathan Lundgren, an agroecologist and CEO of Blue Dasher Farms, Estelline, South Dakota. “But it’s backfiring.”

• One half of all topsoil and soil organic matter has vanished since farmers broke the Midwestern prairie in the 1800s. 

“If we lose the other half, we are in big trouble,” says Peter Scharf, a University of Missouri soil scientist. “Our biggest challenge now across the U.S. in keeping our soil is soybeans. They’re a great crop, but it’s hard to keep soil in place if tillage or rain removes residue on soybean ground.” 



Soil degradation symptoms are often subtle, says Dwayne Beck, who manages the Dakota Lakes Research Farm near Pierre, South Dakota. 

“Soils with half the organic matter they used to have do not hold as much water as they used to,” says Beck. “When rain falls, they saturate faster, just like they did last fall in many areas. During drought, they dry out faster.”

• Fertilizer runoff and leaching are increasingly blamed for fouling water bodies and drinking water supplies. Examples range from phosphorus-induced algae blooms in Lake Erie to excessive nitrate rates in Iowa’s Des Moines River. 

“The clock is ticking,” says Kirk Leeds, CEO of the Iowa Soybean Association (ISA). “We cannot depend on PR and positive stories. We have to have real improvement in water quality.”

• Pests are popping. Waterhemp’s winning in many soybean fields. Last summer, University of Missouri weed scientists found a waterhemp biotype that resists six different herbicide sites of action. In corn, corn rootworm has thwarted every control option tossed its way, including all four Bt-resistant traits.  

“U.S. agricultural policy is that of extraction,” Beck says. He calculates that a 120-car train packed with soybeans destined for foreign or coastal markets contains 400,000 pounds of phosphate used to grow them.

“That’s phosphate that’s not coming back to those farms,” he says. “Ecosystems that leak (nutrients) long term can turn into deserts.”

Well, corn and soybeans pay the bills, particularly in the Midwest’s favorable soils and climate.  

“That’s where processing, livestock, storage, and export structure has developed,” says Dean Fairchild, an agricultural industry consultant. “On top of this are machinery dealers and seed, fertilizer, and chemical suppliers, all geared toward producing corn and soybeans.” 

On prime corn and soybean ground, it’s difficult for another crop to fit. In 1950, Iowa farmers grew 6.619 million acres of oats, a crop that disrupts corn and soybean pest cycles and scavenges excess nitrogen that now goes into tile lines. 

“The problem is that there are no public oat-breeding programs in Iowa that can keep up with the need for higher yields,” says Tom Rabaey, General Mills research agronomist.  

The Practical Farmers of Iowa, supported by General Mills and Grain Millers, Inc., is conducting varietal improvement trials. Still, it’s a challenge in states like Iowa, where hot humid summers lead to yield-robbing and quality-slicing maladies like crown rust. Scant infrastructure for oats means few grain buyers and minimal machinery dealers who sell oats equipment like swathers, Rabaey adds. 

“Mother Nature has been managing ecosystems longer than anyone else,” he says. “She harvests the maximum amount of sunlight and recycles nutrients. A properly functioning water cycle consists of precipitation being consumed by plants and recharging groundwater, rather than running off the surface or percolating into drain tile and degrading water quality.”

No-till helps farmers do this. Ditto for continuous cover through cash and cover crops that slice erosion and spur soil microbes to fuel crop growth, he says.

These tools – coupled with crop diversity, where applicable – can also disrupt weed and disease cycles that increasingly plague corn and soybeans. 

“Fortune 500 companies typically set aside a certain percentage of their budgets for research and development,” says Lundgren. “A farmer could set aside a piece of land and experiment with it. Long term, a diverse system incorporating no-till/cover crops/crop diversity and livestock will build a sustainable system. Once farmers go down that road, they tell me, ‘I never had so much fun farming.’ ” 

Insects often thrive in monoculture cropping systems and under excessive soil disturbance, says Jonathan Lundgren, CEO of Blue Dasher Farms, Estelline, South Dakota. “It used to be we would look at cultural practices like crop rotation to curb pests and use pesticides as a last resort,” he says. “Now, we design everything around pesticides." 

This controls pests, but at the cost of killing predator insects. “For every insect pest out there, there are 400 to 1,700 insects that help us," he says. "I am not against pesticides, but the more you use, the more you need.”

“We were growing sunflowers and applied a chemical that we had to soil-incorporate three times to make it work,” he says. “We ended up with the top 2 inches all dried out and fluffy.” 

Eventually, he and his father could set their planter to seed into moisture. Still, the dry seedbed devoid of any cover would often spur soil to vanish during a flash thunderstorm or windstorm. 

“That fall, I crawled up on the combine with my dad and asked him, ‘What are we going to do if we keep farming like this? There’s not going be anything left for me to farm, much less for my kids because there’s not going to be any soil left.’ ” 

So, Swindler and his father started tagging along with his uncle, Ron Swindler, to workshops like one held by the Manitoba-North Dakota Zero Till Association. They also dabbled on a few acres with the new concept of no-till. 

“We also had a large cattle operation at the same time, and we just weren’t doing a good job of both,” he says. “So, we sold all of our livestock – lock, stock, and barrel – along with all of our conventional farming equipment.” 

Swindler, his father, and uncle bought a Yielder drill in 1982. “It spread our costs over many acres, so there wasn’t as much to bite off at one time,” he says. They gradually converted the farm to no-till over two to three years. 

University of Nebraska scientists calculate each tillage trip nixes ½ to ¾ inch of moisture. The moisture conserved by no-till enables Swindler to grow a diverse crop lineup including winter wheat, spring wheat, canola, peas, sunflowers, and corn. In past years, he’s also planted soybeans and flax. 

“There were people who thought we were nuts, but as time went on, most of our neighbors started no-tilling, and they are doing a nice job,” says Swindler. “It’s been exciting to see that our erosion problems are just a fraction of what they were.” 

The shift has also enabled Swindler to bring his children back to the farm. His son, Nathan, now farms with him; daughters Erin and Hollie live in the area and help out on the farm. 

“We also have five grandsons, and they keep our world tipped upside down and on the move,” he says. “It’s been fun, and hopefully down the road, some of them will be interested in farming.”  

There’s good reason to worry. Soils transitioning from conventional tillage to no-till can endure a three- to four-year period where yields may be compromised, says Jodi DeJong Hughes, a University of Minnesota Extension educator.

Jodi DeJong Hughes Stymied? Try strip-till. It can marry the soil-saving and water infiltration perks of no-till with the soil warm-up merits of conventional tillage, she says. 

“Even chisel-plowing can leave up to 25% to 40% soil-saving residue if the correct (chisel plow) points are used,” she says.

Livestock grazing can strengthen a cropping system, says Dwayne Beck, manager of the Dakota Lakes Research Farm near Pierre, South Dakota.

“People say you can’t graze because you will compact the soils, but that’s not true,” he says. Soils that have been honed with tools like no-till, cover crops, and multiple types of cash crops have the structure to withstand grazing, he says. Cattle manure and urine can naturally fertilize the soil. 

After corn harvest, Dakota Lakes cattle swath-graze a mix of cornstalks and swathed cover crops like oats/ barley/pearl and German millet/sorghum-sudangrass from paddock to paddock. Farm scientists monitor each cow through an activity collar that can be linked to a cell phone. This allows for individual feeding of supplements, Beck says. Mobile, temporary fencing keys movement.

Long term, each cow will be fitted with a collar equipped with a GPS tag that will detect heat and measure time spent feeding and resting. Fitbits mounted on legs will measure cow movement. 

Farm scientists are also working on a self-propelled grazing cell that will automatically monitor an animal's water, mineral, supplement, shade, and shelter when it moves to the next paddock. 

Tim Smith “When you think of how much money and time it costs to put up hay, it’s just insane,” he says. 

Back in 2011, Tim Smith tested his tile water for nitrate-nitrogen (N) the same year he began participating in the Mississippi River Basin Initiative. 

The Eagle Grove, Iowa, farmer didn’t like the results, as tile water leaving his farm averaged 19 parts per million (ppm) of nitrate-N. The standard for safe nitrate levels in drinking water established by the EPA is 10 ppm. 

Ideally, a small grain like oats would scavenge excess N. Still, it’s tough pricewise for conventionally grown oats to crack the corn and soybean rotation. Cover crops, though, are a way to mimic oats in a corn-soybean rotation.

“They help turn a leaky corn and soybean system into a more sustainable one, where we’re not losing nutrients into our water bodies,” says Mark Licht, an Iowa State University (ISU) Extension agronomist.

Smith planted cereal rye in 2011 as a cover crop. He’s since tweaked cover crop seedings on his mix of no-till and strip-till corn and soybeans. He aerially seeds into standing corn in August or drills them into stubble in October. 

He plants soybeans directly into the standing cover crop on corn ground before terminating the cover crop a few days later with glyphosate. Properly setting the planter keys smooth seeding into standing cereal rye. To ensure smooth planting, he replaced fixed row cleaners with floating shark-toothed row cleaners.

In the fall of 2012, he also installed 5-foot-deep by 110-foot-long bioreactor strips filled with 125 cubic yards of wood chips at field edges adjacent to tile ditches. Wood chips typically last 10 to 20 years as they reduce tile water nitrate-N by 50%, says Matt Helmers, ISU Extension agricultural engineer. The wood chips spur microbes to convert nitrate-N to N gas, rather than exiting into tile water. 

The strategy showed almost immediate improvement. Smith’s tile water entering the tile stream in 2013 tallied 14 ppm for nitrate-N, half of the 30 ppm nitrate-N level several miles downstream. Smith’s soil quality also improved.

“I can take a soil penetrometer and not hit hardpan anymore,” he says. “To me, that shows the bioreactor and cover crops are working.”

There’s a cost in all this, although he did receive cost-sharing for the bioreactor. Seeding cereal rye costs around $15 per acre. 

Potential also exists for future benefits. His cover crop initially contained 30 pounds per acre of N in biomass after the first year. This amount may release later in subsequent years, reducing overall N fertilizer costs and less nitrate-N loss potential. 

Less tillage can also accentuate N savings. Although many researchers speculate that increased microbial diversity and activity may increase nutrient availability, most fertilizer recommendations don’t provide an N credit for no-till systems, says Dave Franzen, North Dakota State University Extension fertility specialist. 

However, data he’s compiled from North Dakota sites show long-term (six years or more) no-till fields need less N than conventionally tilled fields. 

“It takes about 50 pounds per acre less N to grow wheat with the same yield and protein under no-till compared with conventional tillage,” he says. 

Smith believes such findings spurred by on-farm practices bode well for improved water quality and soil health.

Thirty-seven years ago, winter wheat-fallow rotations – netting just one crop in two years – ruled areas like central South Dakota. Continual cropping systems changed that, featuring crops like: 

Growing these cash crops and others in central, north-central, and south-central South Dakota increased on-farm revenues in 2014 by $1.6 billion as compared with 1982 on-farm revenues.

“This is because we were able to better manage ecosystem processes,” says Dwayne Beck, manager of the Dakota Lakes Research farm near Pierre, South Dakota. Key tools included no-till, cover crops, and multiple cash crops. 

Planting different crops also deters pests by interrupting life cycles, Beck says. This reduces reliance on pesticides and forestalls resistance of pesticides that are used through decreased pest- selection pressure. 

“Diversification helps farmers be more resilient and increase revenue streams,” says Jonathan Lundgren, an agroecologist and CEO of Blue Dasher Farms, Estelline, South Dakota.

Corn Belt corn and soybean farms won't likely soon sport a sea of other crops. Still, ways exist to mix up a corn-soybean rotation,  says Jonathan Lundgren, an agroecologist and CEO of Blue Dasher Farms, Estelline, South Dakota.

• Plant a cover crop. “Vetch, clover, and peas (or all of them) would work well for corn,” he says. “With cover crops, my experience leads me to advocate that some are better than none, and more is better than less.” 

• Intercrop crops like alfalfa into corn. “Alfalfa is a great nitrogen fixer, and can reduce soil compaction and increase water infiltration," says Marisol Berti, a North Dakota State University (NDSU) forage and biomass specialist.

Normally, farmers seed alfalfa in the spring following a crop like corn. However, NDSU scientists have drilled leafhopper-resistant alfalfa varieties after corn at a seeding rate of 10 pounds per acre. In NDSU trials, interseeded alfalfa gleaned hay yields of 5 tons per acre the next year, compared to yields that resulted from spring seedings of 2.5 tons per acre. 

One drawback exists. During the interseeded year, corn yields decrease around 30 bushels per acre, Berti says. At $3 per bushel, this clips gross returns $90 per acre. 

 At a $100 per acre value for alfalfa hay, though, an additional $250 per acre gross return results from the doubled alfalfa hay yield the subsequent year. This takes the bite out of the lower corn yield, she says. 

• Undersow noncash crop plants beneath a cash crop’s canopy. “During corn planting or directly afterward, we’ve interseeded a six- to seven-species mix including oats, vetch, peas, and clover,” says Lundgren. “It worked out great.”

Each farm likely has an area that may be more conducive to crops other than corn or soybeans, says Jonathan Lundgren, an agroecologist and CEO of Blue Dasher Farms, Estelline, South Dakota. 

Agricultural Land

“People told me that I should till and burn down the weeds on one section of my farm that had been in grass for 12 years and plant soybeans,” says Lundgren. “Instead, we used herbicide to kill the grass and then planted sweet clover. We used no fertilizer and insecticide, and the sweet clover came up green and suppressed the grassy weeds.

“We harvested 300 pounds of sweet clover (per acre) for $4 per pound,” he says. “We also got 300 pounds of honey from the beehives near it. So, the sweet clover will gross around $1,200 (per acre) with little input, plus the money we received for the honey.”

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