Improve residue management to improve soybean stands in 2021

July 30, 2020 | Bethany Baratta

Harvest will be here before we know it, and thus begins the work on the harvest prep to-do list. Iowa Soybean Association (ISA) Agronomy Director Scott Nelson said farmers should also consider their plan to manage corn residue this fall to set up for a successful planting in 2021.

Some farmers in the state experienced poor stands in no-till soybeans this year, Nelson said. Most often, he said, the planter was not able to manage the residue from the previous corn crop and achieve adequate seed-to-soil contact.

“The fix for this begins at corn harvest,” Nelson said.

Corn head maintenance and management is the first opportunity for successful management of corn residue, according to Steve Killpack, a no-till farmer and ISA member near Beebeetown.  

“If you think of your combine as your first step in your residue management, you’ve got to look at it like that,” said Killpack, who is also the founder of Acumen Agronomics in southwest Iowa. “Your combine isn’t just a tool to separate the grain, but actually a tool to prepare the field for the following season.”

Farmers should properly maintain stalk rolls on corn heads and investigate some of the aftermarket styles if replacements are necessary, Killpack advises. Before hitting the field, Killpack adjusts his corn head to ensure proper cutting.

“We tend to cut our corn stalks as low as we can and try to chew up as much of the residue as we can,” Killpack said. “It makes a pretty thick mat which is definitely good for water-holding capacity, but it can be challenging when it comes to planting.”

Planting adjustments

Before heading out to plant in the spring, Killpack replaces coulters and double disk openers to be able to cut through the thick mat created by the residue.  

Killpack plants soybeans in rows 15 inches apart. He uses hydraulic down pressure on his planter, ensuring adequate seed-to-soil contact.

While using row cleaners on a 15-inch planter are not an option, some farmers have found they can manage residue using a single row cleaner per row in a 15-inch planter, Nelson said. Residue managers are not an option for drill-type planters. In this case, Nelson says farmers should increase downforce pressure and appropriately size the residue at corn harvest.

Proper maintenance not only saves valuable planting time, it also ensures seed-to-soil contact, thereby improving crop stands, Killpack said.

The average cost to replace coulters and double disk openers per row is around $75, he said.

“On a 31-row planter it would take 465 acres of soybeans to pay for this update if you could reduce seeding costs by $5 an acre simply by improving stand,” Killpack said.

Residue size considerations

There is a ‘sweet spot’ when it comes to residue size, Nelson and Killpack said.

“The art of good residue management is to size and crush the residue without exposing it to loss from wind,” Nelson said.

Too large, and the residue is difficult to break down.

“When you make residue too fine you actually tend to incorporate residue with your seed and that can lead to a lot of germination issues,” Killpack said. “There’s definitely a sweet spot in making sure it’s sized and will break open so microbes can do their job and break down residue.”

Killpack says he thinks of the residue as part of the complete system.

“One of the things we look at is what our carbon load is that we’re trying to get into the soil,” he said. “There’s a carbon-to-nitrogen ratio, no different than if you’re making compost. I think about it as if I’m making compost in my field.”

He also considers the amount of nitrogen in the soil, especially heading into soybean planting.

Other options

The least desirable management option is mowing the residue, Nelson said. By doing this, the residue is pulverized into fine parts that are vulnerable to loss in the wind. Rather, chopping heads leave 8 to 12 inches of upright stalks that serve as a windbreak leaving the residue less vulnerable to wind.

There are biological products that are marketed to hasten the breakdown of residue in the fall and early spring, Nelson notes. “The problem with these biologicals is the lack of scientific data that they actually work.”

Learn more

Access the 2017 Corn and Soybean Crop Residue Management Impact on Soil Quality, Soybean Yield, and Returns study here.

Stay up to date on all the latest soybean-related news and information by validating and activating your ISA membership at www.iasoybeans.com/membership.

Contact Bethany Baratta at bbaratta@iasoybeans.com.

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