Harvest Recommendations for Soybean Fields With Variable Maturity

Sep 13, 2023

By Mike Staton

Many soybean fields across Michigan experienced uneven and significantly delayed emergence due to the dry weather and soil conditions that prevailed after mid-May (Photo 1). Seed placed into 0.5 inches of soil moisture germinated and emerged well while seed placed into marginally moist or dry soil did not germinate and emerge until the rains resumed in July. In the most extreme cases, emergence was delayed by five weeks or more within a given field.

The delayed and uneven emergence will lead to significant in-field variation in maturity this fall, and producers will have to identify the harvest timing that maximizes net income in these fields. In general, soybean maturity is delayed by one day for every three days that planting/emergence is delayed. Given this information, a 30-day difference in emergence will cause at least a 10-day spread for optimum harvest dates. While 10 days may not sound like a big deal, producers need to understand how factors such as shatter losses, lost yield from overly dry seed, drying charges and discounts, and potential storage problems will affect net income when selecting the optimum harvest timing.

Uneven ripening is common in soybean fields, however the situation in 2023 is different. In most years, the areas that dry down first have lower yield potential than the rest of the field. In 2023, the areas that will dry down first have more yield potential because they emerged earlier and had a longer growing season.

Producers have four options for harvesting unevenly maturing fields:

Harvest each affected field at two different dates.
Harvest the entire field as soon as the early emerging plants are ready.
Delay harvest until the late emerging plants are ready to harvest.
Compromise and harvest the field when the late emerging plants first reach 16% moisture.

Harvesting affected fields on two different dates corresponding to the optimum times for the early and late emerging plants will minimize all the potential problems stated above. However, this is not practical, and few producers will consider this option.

Harvesting the entire field as soon as the earlier emerging plants are ready will reduce shatter losses and harvest delays and provide optimal harvest conditions for the plants having the highest yield potential. However, the later emerging plants may be difficult to cut and thresh and may lead to higher drying charges or discounts at delivery. Unthreshed green pods and green/immature soybeans can also create on-farm drying and storage problems. Combine operators will need to pay close attention to cylinder/rotor speed and clearance settings as they move from ripe to tough plants.

Delaying harvest until the seed in the later emerging plants reaches 13% moisture eliminates the problems associated with the early harvest option. However, if hot and dry conditions occur prior to and during harvest, shatter losses can be excessive in the early emerging plants (Photo 2). The risk of harvesting overly dry beans also increases, reducing the yield of the highest yielding areas of the field due to lost water weight (Table 1). We experienced both conditions in the fall of 2021.

This option also increases the risk of harvest delays and increased shattering due to the pods being exposed to repeated wetting and drying cycles. University of Wisconsin researchers found that harvest losses increase significantly when harvest is delayed by 14 days and continue to increase with further delays. Reducing ground speed and reel speed are important tactics for reducing shatter losses. Delaying harvest is probably a good option if the weather cooperates, and shatter losses and seed moisture losses can be minimized.

Table 1. Net value of a bushel of soybeans at various moisture levels.

Assumptions: Soybean price of $12.40/bu (2023-24 estimated average price from the July USDA WASDE report) and typical elevator shrink and drying charges for 2022.

Compromising by harvesting the affected fields a little later than the optimum time for the early emerging plants and a little earlier than the optimum time for the later emerging plants is a viable option. In theory, this option should narrow the differences between the plants from the two emergence dates. If this option is selected, begin harvesting when the seed in the later emerging plants first reaches 16% moisture.

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Volunteer soybean demonstrating excessive shatter losses common in 2021. Photo by Alex Rutkowske.

If you plan to dry and store soybeans with mixed moisture levels, please consider the following information provided by Ken Hellevang from North Dakota State University.

Unthreshed pods can block the flow in dryers and increase the potential for fires to occur.
Immature soybeans can cause moisture meters to underestimate moisture levels by 1 to 1.5%.
The green color may fade after several months of storage.
Bean pods and higher moisture beans accumulate in pockets and cause storage problems.
Run aeration fans to create a more uniform moisture content as the air picks up moisture from the wet beans and deposits it on the drier beans.
Soybeans of mixed maturity and varying moisture content should not be stored into the summer and should be kept cool by periodic aeration.

Harvesting fields with variable maturity will be challenging this fall. However, producers can minimize harvest and storage losses through careful management.

Source : msu.edu

Video: Why Your Food Future Could be Trapped in a Seed Morgue

In a world of PowerPoint overload, Rex Bernardo stands out. No bullet points. No charts. No jargon. Just stories and photographs. At this year’s National Association for Plant Breeding conference on the Big Island of Hawaii, he stood before a room of peers — all experts in the science of seeds — and did something radical: he showed them images. He told them stories. And he asked them to remember not what they saw, but how they felt.

Bernardo, recipient of the 2025 Lifetime Achievement Award, has spent his career searching for the genetic treasures tucked inside what plant breeders call exotic germplasm — ancient, often wild genetic lines that hold secrets to resilience, taste, and traits we've forgotten to value.

But Bernardo didn’t always think this way.

“I worked in private industry for nearly a decade,” he recalls. “I remember one breeder saying, ‘We’re making new hybrids, but they’re basically the same genetics.’ That stuck with me. Where is the new diversity going to come from?”

For Bernardo, part of the answer lies in the world’s gene banks — vast vaults of seed samples collected from every corner of the globe. Yet, he says, many of these vaults have quietly become “seed morgues.” “Something goes in, but it never comes out,” he explains. “We need to start treating these collections like living investments, not museums of dead potential.”

That potential — and the barriers to unlocking it — are deeply personal for Bernardo. He’s wrestled with international policies that prevent access to valuable lines (like North Korean corn) and with the slow, painstaking science of transferring useful traits from wild relatives into elite lines that farmers can actually grow. Sometimes it works. Sometimes it doesn’t. But he’s convinced that success starts not in the lab, but in the way we communicate.

“The fact sheet model isn’t cutting it anymore,” he says. “We hand out a paper about a new variety and think that’s enough. But stories? Plants you can see and touch? That’s what stays with people.”

Bernardo practices what he preaches. At the University of Minnesota, he helped launch a student-led breeding program that’s working to adapt leafy African vegetables for the Twin Cities’ African diaspora. The goal? Culturally relevant crops that mature in Minnesota’s shorter growing season — and can be regrown year after year.

“That’s real impact,” he says. “Helping people grow food that’s meaningful to them, not just what's commercially viable.”

He’s also brewed plant breeding into something more relatable — literally. Coffee and beer have become unexpected tools in his mission to make science accessible. His undergraduate course on coffee, for instance, connects the dots between genetics, geography, and culture. “Everyone drinks coffee,” he says. “It’s a conversation starter. It’s a gateway into plant science.”