NCSRP Research Director: "Earlier Planting can Increase Soybean Yields"

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With the price of soybean seed skyrocketing, soybean growers are looking for "the sweet spot" - the ideal combination of planting date and seeding rate. The research and education director of the North Central Soybean Research Program offers suggestions to help growers maximize soybean yield and profit potential in 2009.

Growers are planting soybeans between one and three weeks earlier than they did a decade ago. Checkoff-funded research shows that planting earlier can help increase soybean yield, if the seedbed is in good shape.

Checkoff-funded researchers have spent several years studying seeding rates and plant populations. They've found that planting more seed as insurance seldom pays off in higher yields.

Optimal soybean planting dates vary from year to year with the weather. "In general, however, research is showing us that planting earlier can help increase yield - provided your seedbed is in good shape," says Dr. David Wright, Director of Research for the North Central Soybean Research Program (NCSRP).

Three decades of planting date studies in Iowa show that the most favorable planting time for soybeans is from the last week of April through mid-May. Similarly, Illinois planting date studies suggest that planting the last week of April isn't too early, and that there's not much yield loss expected if you can't plant until mid-May.

A two-year Wisconsin Soybean Planting Date Study shows an average yield loss of 0.4 bushels per acre per day when soybean planting is delayed past the first week in May. And a seven-year seed company study at multiple locations throughout the Northern and Central Corn Belt also shows that yield is maximized when soybeans are planted from mid-April through mid-May.

A good seedbed is key

Wright cautions growers not to overlook the importance of a good seedbed if you're planning to plant early. "Little is gained from pushing your planting date if your seedbed is too wet or muddy.

"If you do find yourself planting early in cold, wet and poorly drained soils, or if there's a history of soybean seedling diseases in your fields, consider a fungicide seed treatment to protect your stand," he adds. "Fungicide treated seed may be beneficial in reduced- and no-till fields too, as well as when you're planting seed with a low germination rate or low seed vigor."

Historically, university research has shown that seed treatments generally don't pay. "But growers are planting earlier, and the economics are changing. Seed costs are going through the roof, and seed treatments are being rolled into the price of seed," Wright says. "We're seeing more growers use treated seed and drop the seeding rate."

Lower seeding rates

According to Wright, planting fewer seeds is a good decision. "Checkoff-funded researchers have spent several years studying seeding rates and plant populations. They've found that planting more seed as insurance seldom pays off in higher yields."

Soybean seeding rates will vary depending on seed quality, row spacing, whether you use a planter or drill (and who's driving), soil type, seedbed condition and tillage system. "If you've got a good planter that gives you uniform seed placement and depth, and you're not pushing the early planting envelope, you're probably in the 150,000 to 160,000 live seed range," he adds. "If you're drilling beans in cold, muddy conditions, you'll be at the higher 190,000 range."

The goal is a final soybean plant stand of 100,000 to 125,000, depending on where you farm. In the northernmost areas of the Midwest, agronomists recommend higher final harvest stands.

Wright encourages soybean growers to check with their university agronomist for help determining seeding rates for optimal final stands. "You might find slight variations in recommendations, but there's one thing all university agronomists agree on: Dropping 225,000 to 250,000 seeds per acre is way too high. With the price of seed, that's good news for growers."

The Plant Health Initiative represents a cooperative partnership between soybean checkoff boards and land grant universities from 12 North Central states, as well as private industry. The initiative's goal is to act as a resource that collects and dispenses valuable management information on a variety of soybean pests and diseases. The Plant Health Initiative receives its funding through soybean checkoff dollars and private industry support, and is administered by the North Central Soybean Research Program (NCSRP), its primary sponsor.

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David Wright, Ph.D.
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