Compared to the Midwest, the South is a difficult environment for growing soybeans. Questions remain on how best to deal with seed and gain a stand in the Mid-South. A new, extensive, three-year research effort — sponsored by the Arkansas Soybean Promotion Board (ASPB) — has begun to address the gaps in knowledge.
“Soybean seed quality varies from year to year,” says Rick Cartwright, University of Arkansas plant pathologist. “It depends on the weather, when and where it was produced, how it was stored and other things. There are good and bad years with soybean seed. Sometimes, though, even what we think is good seed just doesn't come up.”
This is not the fault of seed companies. “The companies do a great job — the best they can, no doubt. It's obviously in their best interest to maintain quality. And they strive for that.”
Yet, there are sometimes “mysterious” stand failures — especially in the South. In Arkansas, growers now plant soybeans from March through mid-July. The seed supply, produced the previous year, must last for a long planting season and needs to maintain quality whether it's planted in March or July.
“That's a challenge in itself. Another thing the South is facing that isn't such a problem in the Midwest is our planting conditions are so diverse. In fact, you could argue that planting conditions in the South are actually hostile to soybean seed. That often leads to mixed results with stand establishment. Even though we use a lot of seed treatments, they don't always help.
“We're also now planting in no-till seedbeds and in rotation with several different crops — rice, corn, sorghum, cotton.”
In a bid to save money due to increase expense of modern seed, farmers are also willing to cut seeding rates. For those in a non-ideal planting situation, doing so can cause problems in getting a stand.
Complicating the situation is seed quality can't be judged on one thing.
Germination — the process of seed taking in water and producing a seedling under optimum conditions — is checked in a lab test and the results, by law, must be printed on seed bags. For many years, farmers have relied on germination test data.
However, seed quality isn't solely defined by the germination test. There's also a very complex characteristic of seed called vigor. The vigor of seed includes a set of factors that still aren't fully understood. However, in the last few years, there has been a lot of progress in measuring it.
In most states, and companies, “there's a lot of emphasis on testing seed for vigor. There are all kinds of tests to determine the seed's properties — will it produce a normal seedling under certain conditions? Maybe conditions being checked are cold temperatures, accelerated aging under hot, humid conditions, membrane leakage tests, and so on.
“Put all those tests together and you'll have a better idea that the seed being tested has good potential for germination under optimum conditions but you'll also know that the seed has better potential to produce a normal seedling that'll survive under less than optimum conditions.”
The Association of Official Seed Analysts and the International Seed Testing Association write the rules for the world's official seed testing. A few years ago, both adopted the accelerated aging test as a standard, reproducible vigor test of soybeans. Since then, many companies and states have used accelerated aging tests to supplement germination and other tests to further define seed quality.
“It's a good way to get information about your seed lot and where you might use it, or not. If the seed has low vigor you might not want to plant it. If there's moderate vigor, you might still use it under optimum conditions but avoid using it in certain tough planting situations. Seed testing high in both the standard germ test and the accelerated aging test would be the lots you could have the highest confidence in.”
With that background, the ASPB asked researchers at the University of Arkansas to conduct a comprehensive project looking at soybean seed quality issues.
Over the years, much of the seed quality research has been done in the Midwest. “Certainly, that done in their fields might not correlate as well in the Mid-South. We need to validate some of this information under our conditions.”
Also part of the effort is an education component. “We'll try to explain as much as we can about all this to our growers and the industry. That could include how farmers can find out particular data on seed they're interested in purchasing. And, once procured, how they can use that information most effectively.
“Also, we want to know where seed treatments, new seed-coating technologies and the like fit into this. Do they really help preserve seed quality in storage and the field? Which do the best job? Where is it most appropriate to use those?”
Currently, a small, seed-quality test lab is being established at the University of Arkansas in Fayetteville.
“We'll also be working with the Arkansas Plant Board and other states' seed testing labs. At planting, beginning on April 28, we're asking Extension personnel in the field and grower organizations to help us collect planting seed being used in fields across the state. The sampling will continue through mid-July.”
Those samples will be taken to the aforementioned labs for germ and accelerated aging tests. It's hoped that the 500 to 1,000 evaluated samples will provide a good initial dataset on soybean seed quality being used during the entire planting season in the state, and what factors may have contributed to that quality.
“And we're not just looking for stand failures. Knowing what seed came up perfectly for a great stand is just as important.”
Another aspect of the research will be field tests. This year, an industry cooperator has provided seed from a variety that was determined to have varying quality — “some very good, some middling, some poorer.
“Using that seed, we'll work with Chuck Farr, a crop consultant in Crittenden County who has a strong interest in seed quality. The seed will be planted in some different conditions in his area.”
Another planned location for field tests is near Waldenburg in Poinsett County. “There are some stand problems with soybeans on the silt loams around there. Having two different locales and soil types — but planted in the same seed — should provide some interesting data.”
Tying the various aspects of the project together will be a “major chore,” admits Cartwright. “But we've got a great group in the division focused on it. We've got a staff person already reassigned to work on lab testing. We also have a coordinator reassigned to work the education program.
“We'll use every opportunity to provide growers this information — field days, winter grower meetings, even a Web site.”
The first year will largely be an establishment phase of the project. “But we expect to get a lot done. The successes or failures in the initial year will define the research and education efforts in years two and three. We'll push hard to see what we can get done this first year.
“Frankly, when going into a new program like this, the first year involves a lot of brush cutting.”