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Here are issues to watch for as you scout soybean fields this spring.

Tom J Bechman 1, Editor, Indiana Prairie Farmer

March 21, 2019

3 Min Read
soybean field
CLOSE CANOPY: These soybeans were nearing complete canopy closure by the third week of June. Agronomist Stephanie Smith says that helps them harvest maximum sunlight during the season.

How quickly and cleanly a horse gets out of the gate in the Kentucky Derby helps determine where the horse finishes. The same concept applies to soybeans. Crops that “get out of the gate” quickly and move through the first part of the season without major issues are often set up for top yields when weather cooperates.

“We’re strong believers in planting soybeans as soon as conditions are right,” says Stephanie Smith, an agronomist with Golden Harvest in Indiana. “You don’t want to mud them in; soil conditions need to be right. But the earlier you can plant soybeans, the better. Several studies show that planting soybeans early, even before corn if necessary, helps them take maximum advantage of sunlight throughout the season.

“What you’re going for is capturing as much solar radiation as possible. That’s why early planting is so important.”

Here are six things Smith keeps in mind early in the season:

1. Soybeans need sulfur. Smith is a proponent of applying 50 to 100 pounds of ammonium sulfate before planting soybeans, when possible. Like corn, soybeans need sulfur, and they aren’t getting as much from the environment as they did before utility plants added scrubbers and cleaned up the air.

2. Reduce the seeding rate. If you’re planting early, you can reduce the seeding rate, Smith says. She also recommends making sure seeds are protected with a good seed treatment package when planting early. As you plant later in the season, say into late May, you may need to increase the seeding rate.

3. Push toward early canopy closure. Shaun Casteel, Purdue University Extension agronomist, has a saying for soybeans: “Green to the eye by the Fourth of July.” That means he wants full canopy closure.

Smith would prefer full canopy closure by June 21, the longest day of the year, to maximize harvesting sunlight. Early planting and reduced seeding rates are part of the plan. “We want a shorter plant with lots of nodes,” she says. “That’s where yield comes from.”

4. Manage soil fertility. Once you have pods and nodes, pumping up seed size depends upon having proper soil fertility in place and getting a boost from favorable weather conditions, Smith explains.

5. Scout for early-season issues. You need to be in the field during May to see if there are disease or insect issues. Bean leaf beetles sometimes appear early, feeding on leaves. Monitor their activity and treat if necessary, Smith says. She notes that bean leaf beetles can be the vector for a disease that can result in green stem syndrome in the fall. May is also the time when soybeans may be infected with sudden death syndrome if environmental conditions are right, even though symptoms don’t show up until later.

6. Manage fields separately and be ready to adjust. Not every field or even every part of each field is the same, Smith emphasizes. As much as possible, design a plan that’s best for each field or part of a field.

“It’s great to sit down and write a plan in February, but be ready to adjust on the go as conditions change,” Smith says. “Make in-field adjustments based on your observations.”

About the Author(s)

Tom J Bechman 1

Editor, Indiana Prairie Farmer

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