Beware of Soybean Seed Quality Problems

Test results show some seed in Iowa testing only 80% to 85% germination; a few lots are even lower.

Most seed industry people this past winter thought Iowa would be okay, because most of the soybean seed that was having problems with lower-than-normal seed quality was in maturity groups that are planted in areas south of Iowa. "But we are now finding test results showing some soybean seed in Iowa testing only 85% or less germination," says Palle Pedersen, Iowa State University Extension soybean agronomist. Normally it's 90% or above.

"Don't get me wrong. There is a considerable supply of seed that is of good quality this year for planting in Iowa maturity zones. But there is also some seed that is not of the best quality this year," says Pedersen. "The most popular soybean varieties are getting close to being sold out. So if you have to replant, you may run into trouble trying to get some good seed. That is something to keep in mind this spring."

If you plant too early and run into a problem and have to replant, you may have to accept some seed that is less in quality than what you are used to, he adds.

Read the seed tags and work closely with your local agronomist. For example, if your seed tag says the seed has an 80% or 85% germination score, you need to increase your seeding rate and adjust for that 80% or 85% to be sure you have enough stand. "You don't want to get below 100,000 plants established per acre this year in Iowa," says Pedersen. "Because of the high grain prices there shouldn't be anyone in Iowa planting less than 140,000 seeds per acre in 2008 without using a seed treatment. If you use a seed treatment on the soybeans you may be able to go a little bit lower on the seeding rate per acre, and in addition remember you need to adjust for the percent germination you read on the seed bag's tag."

Compensate with increased seeding rate

If you have 85% germination rate on a seed tag, how would that change your seeding rate? "It's difficult for us to suggest a seeding rate recommendation for each farmer," he explains. "There are so many variables that influence your stand establishment. Such as planting depth, speed, seed quality, crop residue management—all these variables—whether you use a fungicide seed treatment or not—will influence your final stand establishment."

So it's very difficult for Pedersen to say "This is the amount you need." He explains that most farmers, if they are used to planting 150,000 seeds per acre and fail to get a stand that is acceptable this spring--if they know if they plant in a normal year 150,000 seeds per acre to get a final stand of 110,000 soybean plants, that should be fine for this year. But if they have a bag of seed that says 85% or 80% germination instead of 90%, then they know they need to bump up the seeding rate a little—perhaps a 10% or 15% increase on the seeding rate. So instead of 150,000 maybe you should seed 165,000 seed per acre.

All the seed companies Pedersen has talked to during the last couple of weeks are aware of the lower-than-normal germinations of some seed lots. Companies are working very closely with their growers to assure that they don't get anyone planting too low a seeding rate. This is the year where you don't want to get below 100,000 because of high grain prices.

Plan ahead so things go your way

He advises farmers to use thoughtful planning. Things beyond your control can change but you should plan carefully so you don't make mistakes and end up having to replant.

"It is now a month before the start of corn planting and we may have a wet seedbed this year," says Pedersen. "And soybean seed quality may not be as good as we see in normal years. You may be fortunate and be able to get good quality seed. But there are some varieties from some companies that have lower- than-normal germination this spring. Read the seed tag and talk to your local agronomist. Be sure you don't plant too few seeds out there, so you don't get too low of a stand. If you have to replant, that may be a problem."

Sometimes farmers buy more seed than they need and decide the week before planting that they are going to plant more corn or more beans. Many times they'll return some seed. So there may be plenty of seed this spring. "But with the wet soil conditions Iowa has and water sitting everywhere, we haven't really dealt with this type of situation the last several years—considering the wet winter we just had," says Pedersen. "This is a reminder how important seedbed conditions are. If you don't do a good job of putting seed into the ground and get the crop off to a good start, the results will stay with you and cause problems later in the season."

TAGS: USDA Extension
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