Soybean quality: What farmers need to know
October 15, 2026 | Kriss Nelson
Wet September weather has left some Iowa soybean farmers navigating grain quality, grading adjustments and potential discounts as harvest continues.
Purple discoloration and other quality concerns have created uncertainty about how soybeans will be evaluated and whether buyers will accept them. Meanwhile, strong yields are putting pressure on available storage space at some Iowa cooperatives.
But Bobby Martens, executive director of the Iowa Institute of Cooperatives, cautions against assuming the worst for Iowa's soybean crop based solely on appearance. After surveying cooperative members across the state, Martens says quality varies by location, with some areas experiencing greater challenges than others.
“There's certainly discounts that people haven't experienced for several years,” he says.
Martens offers guidance on common questions farmers may have about grading, discounts, delivery and marketing options:
Martens' answers to common questions:
Why are my soybeans purple, and does that mean they're damaged?
Purple mottling is caused by the fungus Cercospora kikuchii, which also causes Cercospora leaf blight. The fungus can leave purple discoloration on soybean seed coats.
However, the purple appearance alone doesn't indicate a quality problem, Martens says. Some samples may look severely damaged because of the discoloration, even when the soybeans remain suitable for processing.
Will I get docked for purple soybeans?
Generally, no.Ag Processing Inc. (AGP) and other domestic processors have indicated they can accept purple-discolored soybeans without discounts for the discoloration. According to USDA’s definition of soybeans of other colors (SBOC), purple soybeans are not considered in SBOC
There are reports that some early-harvested soybeans were initially discounted due to purple mottling. In at least some cases, those early loads were regraded, and farmers received additional payment.
If your soybeans were discounted early in harvest because of purple discoloration, ask your cooperative whether those loads qualify for review, but be aware that coloring issues other than purple mottling exist in parts of Iowa.
Uncertainty remains about how export markets might respond to purple-discolored soybeans, although Martens says domestic processors have generally indicated they can use them.
Are purple beans graded differently than moldy, shriveled or cracked beans?
Yes. Purple discoloration and other types of soybean damage are different quality concerns.
Cooperatives follow established grain grading standards established by the U.S Grains Standard Act, and the type and extent of damage and coloration can affect how a load is evaluated.
Many cooperatives send samples to outside grading facilities or other buyers to compare results with their internal assessments. The entire grain industry also works closely with the USDA’s Federal Grain Inspection Service (FGIS), which administrates the U.S. Grains Standard Act. These checks help maintain consistency, particularly during an unusual harvest when grain quality varies.
What's the difference between yellow and mixed soybeans, and why does it matter to my elevator?
Soybeans receive both a numerical grade and a classification as yellow or mixed under federal grain standards.
In 2023, soybeans of other colors were removed as a factor in determining numerical grades. However, the distinction between yellow and mixed soybeans remains. Soybean samples containing more than 10% soybeans of other colors are classified as mixed.
Purple-mottled soybeans are excluded from that color calculation. However, some areas of Iowa still have enough soybeans of other colors to exceed the 10% threshold, while other areas are only slightly under 10%.
Being classified as mixed doesn't necessarily mean the soybeans have lower oil content or are unsuitable for processing. However, the classification can affect where cooperatives can market the grain, particularly in export markets.
Some Iowa cooperatives have enough qualifying yellow soybeans to assemble rail shipments, while others are holding off on shipments because they cannot assemble enough grain that meets the classification requirements.
This creates a challenge for cooperatives purchasing soybeans from farmers. If a cooperative applies discounts because of color concerns, it risks losing deliveries from farmer-members. However, purchasing grain without accounting for classification requirements could limit opportunities to sell those soybeans later, particularly to export markets. If export opportunities are limited, this large soybean crop will flood the domestic market.
Before delivering, ask your cooperative whether potential discounts are related to numerical grade, soybean classification or specific buyer requirements.
Why might my soybeans receive a different grade or discount at another elevator?
Grading assessments and buyer requirements can vary.
An elevator receiving mostly good-quality grain may face different inventory challenges than one receiving large quantities of damaged or discolored soybeans.
In areas where quality problems are concentrated, cooperatives may have fewer options for managing incoming grain with varying quality characteristics.
Before delivery, ask about grading standards and discount schedules rather than assuming every buyer will handle questionable grain the same way.
My soybeans don't look right. Should I call the elevator before hauling?
Yes. Take a representative sample to your cooperative or potential buyer for evaluation before delivering questionable grain. Ask how the sample will be graded, what discounts might apply and whether the location can accept the load.
Do not assume soybeans that look damaged have little or no market value. Some processors may accept grain that other buyers are less willing to purchase. Checking with different buyers could help identify additional marketing options and avoid unnecessary losses.
Could my elevator reject a load of damaged soybeans?
Yes. Some elevators may reject loads because of quality concerns, depending on the condition of the grain and the buyer's requirements. However, quality-related rejections do not appear to be widespread across Iowa, and I know of no loads rejected from cooperatives. There are reports of rejected loads at processors
If your load is rejected, ask which quality factors caused the rejection and whether another buyer may accept the grain. Different buyers have different requirements, so other marketing options may be available.
Keep in mind that an elevator may also be unable to accept soybeans because of limited storage space rather than grain quality.
What if I disagree with the grade or discount on my soybeans?
Ask your cooperative whether the sample can be regraded or independently evaluated. Cooperatives sometimes send samples to outside grading facilities to verify their internal assessments, and farmers can inquire about similar options.
Ask whether the original sample has been retained and what procedures are available for requesting another evaluation. Because results can vary between samples, consistent sampling is important.
For an independent assessment, consider asking about a recognized state or federal grain inspection service. This can help clarify the grade and provide additional information when questioning a discount.
What if my elevator doesn't have room for my soybeans?
Contact your cooperative or buyer before hauling to confirm available space and delivery options.
Exceptionally strong soybean yields, particularly in northern Iowa, have filled storage facilities at some locations. You may be asked to deliver elsewhere or wait until space becomes available.
Limited storage space can also affect local soybean prices. Basis has widened in some areas as cooperatives manage large deliveries.
Before deciding where to sell your soybeans, compare current bids, delivery locations and available storage space.
Should I store questionable soybeans or try to sell them right away?
That depends on the grain's condition and your available marketing options. Severely damaged soybeans may not store as well as higher-quality grain, increasing the risk of additional quality losses.
If storing questionable soybeans on the farm, monitor them closely for signs of deterioration, particularly when damaged beans are stored with higher-quality grain.
Before deciding to store or sell, weigh the potential for further quality deterioration against current discounts and available marketing opportunities.
Written by Kriss Nelson.
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