Leftover Beans

Treated seed requires careful management and disposal.

Emily Unglesbee
By  Emily Unglesbee , DTN Staff Reporter
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Don’t leave leftover treated soybeans exposed to wildlife or where it can contaminate water sources. Growers have to either store, plant, bury or destroy it, Image by Pamela Smith

If prevented planting acres left you with unused treated soybean seed, think twice before holding that seed for planting next year.

Because of their oil content, soybeans are not as stable as corn in storage, which is why seed companies are reluctant to accept treated-soybean seed returns. “It’s hard to store soybeans for even just a year and have confidence that you will get good germination,” explains Kris Ehler, a sales agronomist with Ehler Bros., a family seed and crop consulting company in Illinois.

In fact, an Iowa State University study found that soybean seed germination rates dropped below 20% after 16 months in a warehouse with no climate control.

Moreover, treated soybean seeds generally contain some combination of pesticides, usually a fungicide and insecticide. That means growers cannot send them into the commodity stream for food, feed, oil processing or export.

Nor can growers discard them casually; they have to follow federal and state regulations on the disposal of treated seed, notes the Pesticide Environmental Stewardship (PES), an industry and university-led group that advises on safe pesticide management. Do not try to broadcast or spread the seed at a high seeding rate and then incorporate it; this risky strategy could leave seed exposed or violate the label of certain seed treatment active ingredients, the PES warns. Composting pesticide-treated seed or burning it in a home or shop stove is also illegal and unsafe.

So, what are your options? It boils down to these four: store, plant, bury or destroy, experts agree.


When attempting to store treated soybeans, cool and dry conditions are best. If both are not possible, dryness is the most important factor, explains Susana Goggi, a seed scientist with Iowa State University.

Back in 2013, Goggi conducted a study to evaluate how well treated and untreated soybeans handled storage. She found that both treated and untreated beans required near-ideal storage conditions--a controlled climate of 50ËšF and 50% relative humidity--and high starting quality of the beans to maintain their germination rates above 90% for 20 months.

When the soybean seed was kept in a warehouse with no climate control, germination rates dropped
to 80% in 12 months and fell quickly below 20% by 16 months.

Keep in mind that growers storing seed in 2019 would likely see much lower germination rates than this study produced because of the lower starting quality of the soybean seed out there, cautions Ohio State University Extension plant pathologist Anne Dorrance.

“The issue is that a lot of soybean seed from 2018 was really poor quality,” she says. “We had reports from all my counterparts across the Midwest seeing high levels of Phomopsis and Diaporthe infections in soybean seed.” Seed lots with 80 to 85% germination rates were not uncommon this spring, and they have already endured months in storage.


Nonetheless, if you have a significant amount of unused treated soybean seed, you could possibly recapture some of its value by storing it for the spring of 2020 rather than taking a complete loss on it, Ehler says.

“You would need to find the most consistent environment you can, such as an insulated or air-conditioned shed,” he says. “In February, pull samples, get a germination test and find out what you’ve got.” Even germination rates as low as 75% could be blended with higher-quality soybean seed of the same maturity group next year, he notes. At germination rates below 50%, the seed is probably no longer worth your time and resources to plant, Goggi believes.

Growers can also rent space in a storage facility with controlled temperature and humidity. “You’ll have to calculate: ‘If my germination drops to this level, I will have to bump my seeding rate to this level, and will it cost me that much money versus what it costs for this controlled environment,’” Ehler advises.

If your treated seed is stored in bins, Goggi recommends sampling from the middle of the bin, not the top. “Skim the top part of the seed off, and take a sample from deeper in the bin, where there is going to be less fluctuation in temperature and relative humidity, and use that to determine germination,” she says. Using the same logic, sample germination rates from both outside bags and inner bags when evaluating the viability of seed stored in a large pile of paper bags.


If you must dispose of treated seed, first check the label. Seed treatment active ingredients may come with a host of specific restrictions on disposal. Your state pesticide regulators might have their own rules, too. You can find their contacts at aapco.org/2015/07/28/resources-2. Then consider the following:

> Plant it: Small quantities of leftover treated seed can be planted at proper seeding depths into “fallow or other noncropped areas of the farm,” according to the PES. Increasing soybean seeding rates to accommodate for late planting and lower germination rates could also help use up excess soybean seed, Ehler notes.

> Make it a cover crop: Soybeans can double as a cover crop, but only if your insurance company agrees. Consult with an insurance agent first.

> Bury it: Seed burial is an option, but only if it is allowed by the label, and if growers avoid burying it near water sources.

> Outsource it: Some state municipal landfills can dispose of treated seed as hazardous waste. Other facilities can incinerate them, such as waste-management facilities, power plants, cement kilns, ethanol plants and even some elevators. See more details on each state’s hazardous waste programs at www.epa.gov/hwgenerators/links-hazardous-waste-programs-and-us-state-environmental-agencies.


> The Pesticide Stewardship Alliance’s Treated Seed Disposal guide

> The American Seed Trade Association Guide to Seed Treatment Stewardship

> University of Minnesota Safe Handling Treated Seed fact sheet


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