Cover crops help soil profitability

Stopping soil erosion was the driving force behind the Sylling family’s decision to switch to no-till more than two decades ago. At the time, brothers Myron and Mikal farmed in partnership with their father, Karl, on a corn-and-soybean farm in the hilly country of southeastern Minnesota, near Spring Grove.

Switching to no-till reduced erosion, but didn’t stop it completely. Meanwhile, soil health improved at a mere snail’s pace. When the brothers took over the farm from their father in 2012, they began searching for ways to eliminate erosion completely and make greater inroads in soil health.

Growing cover crops seemed like the obvious next step, and they soon added them to their cropping system. Greater improvements in soil health came quickly.

“The first year of growing cover crops we saw an explosion in earthworm activity in the soil,” says Myron Sylling, a mentor with the Minnesota Soil Health Coalition. “We also saw water infiltration improve. Because the cover crops infiltrated water into the soil, there was so much less water runoff during and after a rain event. It helped the soil stay in place. Because of that, we had to do less repairing of ditches in the fields.”

After years of growing cover crops, the Syllings today see water-infiltration rates that are nearly triple earlier rates, along with increased levels of soil organic matter, greater biological activity in the soil, and higher yields.

Cover Crop Challenges

While cover crops have brought these valuable benefits, they’ve brought challenges, too. Finding the cover crop species that work best for them and discovering the most effective ways to establish the cover crops in the fall has been a process of trial and error. For the Syllings, cereal rye has emerged as their cover crop of choice. They’ve adopted frost seeding as a time-tested supplement to drilling cover seed after harvest.

“In addition to rye, we’ve tried oats and had some success with that as a cover crop,” says Sylling. “We’ve also tried drilling hairy vetch, but we haven’t had success with it overwintering. We’ve tried dwarf essex rapeseed, too, and we have found that the rapeseed can volunteer in our cash crops even after a year or two of it being grown as a cover crop.”

In their usual sequence of incorporating cover crops into their cropping system, the Syllings drill cereal rye after harvesting soybeans. Because they harvest the beans in late September through the first half of October, this timeframe permits the seeding of rye early enough for the rye to get started in the fall and overwinter.

However, with corn, the harvest occurs later, starting in mid-October and providing only a narrow window of opportunity for a fall-planted cover to get started.

“If the temperature stays relatively warm, we can still drill cereal rye after corn harvest and get a catch,” says Sylling. “But if the ground freezes up, drilling doesn’t work well for us. It did that this past year – the fall of 2022 – and we decided to frost seed the rest of the rye in the spring of 2023.”

Typically, the Syllings frost seed the cereal rye in mid-March by broadcasting it over the top of the corn residue using a fertilizer spreader with a 60-foot spread.

“To avoid working in muddy ground conditions, we typically go out with the spreader early in the morning when the ground is still frozen,” he says. “Or, we might start later in the evening.”

When frost seeding, the Syllings nearly double the seeding rate they use when drilling rye seed. “For frost seeding, we apply 56 to 60 pounds per acre,” says Sylling. “When we’re drilling rye on bean ground, we seed at a rate of 35 pounds per acre and 45 pounds per acre on corn ground. Even for drilling, we’ll increase the seeding rate when we come to spots in the field where there’s the potential for water erosion. There, we’ll increase the seeding rate to 60 to 70 pounds per acre because we know that a rye cover crop seeded at only 35 pounds to the acre won’t handle erosion.”

The spring emergence of the frost-seeded rye in corn stover is not uniform but still protects the soil and suppresses weeds, says Sylling.

However, he speculates that corn head designs could determine whether or not frost seeding of cover crops works on corn stover. “We harvest with a straight corn head,” he says. “It chops the residue and lays most of it next to the corn row. So we don’t get much of a cover crop catch for about 5 inches on either side of the row, but we get a good catch in the middle of the row, where there’s less residue.

“You might have less success with frost seeding on corn stover if you were harvesting with a chopping corn head,” he says. “Because that type of head lays the residue in a thick layer across a larger area, you might have trouble getting seed-to-soil contact.”

Depending on weather, even frost-seeded rye may reach a height of about 6 inches by seeding time in spring, while drilled rye might be about a foot in height. Weather permitting, the Syllings plant soybeans from mid- to late April and corn from late April to early May.

With both cash crops, they seed into the rye green and terminate the cover crop after planting.

Improved Water Infiltration

While improved water infiltration was one of the early benefits they saw from growing cover crops, it has continued to improve over time.

“Water infiltration has nearly tripled what it was when we were just doing no-till,” says Sylling. “Water now infiltrates at a rate of 7 inches an hour for the first hour. In large rain events we don’t see water running off our farm.”

Soil organic matter has increased dramatically as well. Levels of organic matter stayed stagnant during the years they practiced straight no-till. But within just four years of growing cover crops, the organic matter jumped, says Sylling.

“Before we started growing cover crops in 2013, our soil organic matter was 2.8% to 3.2%,” he notes. “Now, we’re running between 4% and 5% soil organic matter.”

Periodically, the Syllings run Haney soil tests to get a reading of other soil health parameters. An early test they ran showed the immediate response of soil life to a cover crop. “The first year on a drilled cover crop, I did a Haney test on ground that had had a cover crop on it for just two months and also on ground that had no cover crop,” he says. “The biological activity on the cover cropped ground was nearly twice what it was on ground with no cover crop.”

Carbon

While increases in soil carbon are going hand in hand with increased levels of soil organic matter, the present carbon marketing system offers only limited opportunity for the Syllings because of the length of time they’ve been implementing soil health practices.

Nevertheless, the carbon itself is invaluable to their cropping system. “It’s the carbon in the soil that’s increasing water-holding capacity and yields,” he says. “It’s hard to put a value on it. The soil biology, carbon, and organic matter are working together to make soil nutrients more available to crops. Because of that, the soil system is helping to reduce our cost of production.”

Yields on their 1,550 acres of non-GMO crops have increased over time. “Our corn typically yields 225 to 230 bushels per acre, while soybeans yield 65 bushels per acre,” says Sylling. “On corn, we believe cover crops have given us a 25-bushel-per-acre increase, and a 5- to 7-bushel-per-acre increase on soybeans.

“Along with other management factors, growing cover crops has definitely increased our profitability,” says Sylling.

Learn More

Myron Sylling / myronsyl@gmail.com / 507-459-7792