The crop budget numbers don’t lie, and they’re telling growers to plant soybeans in 2009. Following a successful crop this past year, Alabama farmers might just follow that recommendation.
“Many producers were growing soybeans for the first time last year,” said Dennis Delaney, Auburn University Extension agronomist. Delaney spoke at the Central Alabama Cotton Workshop, held recently in Autaugaville, Ala.
“In 2008, we grew 350,000 acres of soybeans at 35 bushels per acre,” he says. “Some of our late beans received good rainfall, and some growers in north Alabama made 60 to 70 bushels per acre.”
For those who are new to growing soybeans this year, maturity groups range from Group 000 to Group X, says Delaney. “In Alabama, we normally grow from Group IV to Group VII or VIII. Generally speaking, Group IV and under are indeterminate — they can triple in height from the time they start blooming. Maturity Group V and above are determinate or later beans. When they start blooming, that’s pretty much it. What you have at bloom is essentially what you’ll have at the end of the season,” he says.
It’s important, says Delaney, for all growers to remember the basics of soybean production. “We need to soil test and lime, and we need to go ahead and inoculate those seed with the right rhizobia to fix the nitrogen for you. But if pH is too low, they just won’t be able to do the job. Soybeans are very sensitive to low pH in the soil,” he says.
In fields in which soybeans haven’t been grown for awhile, Delaney says the standard recommendation is that growers inoculate. “Like with all other legumes, there’s a particular kind of rhizobia for soybeans. At $1.25 to $1.50 per acre, it’s fairly cheap insurance compared to having to go back in and top-dress with expensive nitrogen,” he says.
Some states have shown a slight yield boost by inoculating, even if they had a history of soybeans in the field, he says. “We haven’t seen that in our tests in the last couple of years. We’re seeing an increase of only 1 to 1.5 bushels, so it’s hard to justify,” says Delaney.
“Just as with cotton, it pays to use a seed-applied fungicide in soybeans. I have seen — especially when we plant some of the early soybeans — particularly sentinel plots in late March or early April – that beans will sit there for two or three weeks. But they’ll come up if they have a good fungicide package on them. If they don’t, they’ll rot. It buys you a little time in case the weather is cool and wet,” he says.
Soybeans, he says, are a very poor rotational crop if you’re growing peanuts. The two crops share several diseases, including white mold and cylindrocladium black rot.
“We had a variety test in north Alabama where white mold came into soybeans following peanuts under irrigation. It came in at about the middle of July and killed about one-third of the field while stunting the remainder of the soybeans. We made about 30 to 35 bushels under irrigation.”
Nematode resistance, says Delaney, is another important consideration in soybean production, especially for root-knot nematodes. “Particularly as we get into the Group IV’s, we find we don’t have a lot of resistance to nematodes. Most of the Group V’s have some resistance, but it varies. Look at the charts from the seed companies and see where a variety falls in terms of resistance. You may want to move to a different field or try and find another variety. Very few varieties are resistant to reniform nematodes — there are just a handful, so watch out for that.”
A lot of disease resistance — to both foliar and soil-borne — can be “bought in the bag,” says Delaney.
He recommends that growers spread out their soybean maturities, from early to late, insuring the beans are planted on time.
“If you have late-planted corn and you can’t get it out on time, along with early soybeans, many times they’ll be on top of one another in August. Corn may wait a little while, but these early planted Group IV soybeans will wait only a week or so.”
Like cotton, says Delaney, soybeans can be forgiving when it comes to plant populations. “Usually, about 150,000 plants is optimum. That gives a quick shading of the ground and translates to about 12 seed per foot on 36-inch rows and about 10 seed per foot on 30-inch rows. In tough conditions or when drilling or no-tilling beans, you can bump up that number.”
If farmers are fortunate enough to receive ample rainfall this year, they also are likely to see Asian soybean rust, he says. Alabama has about 25 sentinel plots located throughout the state, and these will be checked weekly during the production season, says Delaney.
“If we do get a wet, rainy summer, our research over the years has shown an average yield increase of about 6 bushels per acre whenever we use one of the new fungicides like Headline and Stratego, even if we don’t have heavy disease pressure.”
Soybeans, says the agronomist, don’t respond well to deep tillage. “If you plant after wheat and you’ve subsoiled or deep-tilled the wheat, just drop and no-till plant soybeans. There’s no need in losing that moisture and straw.”
Traditionally, Alabama growers have planted Group V soybeans in the northern part of the state, Groups V and IV in the central region, and Groups VI and VII in the south, says Delaney.
“Over the years, we’ve moved to an earlier maturity group throughout the state. Normally, we planted from May through mid-June after we had done everything else and we tried to harvest in September and October. In the last few years, the Group IV Early Soybean Production System (ESPS) has been used by some growers. With each planting system, there’s different management with different pest problems for each one. With ESPS, we’re trying to move it back to earlier in the year.
“This system shifts Group IV planting to mid-April, and then you have seed fill in July and maybe early August. Before we run out of moisture, we get them out in mid-August. Normally, there’s a lot less worm pressure with this system, but you need to watch for stinkbugs. In 2005, some growers saved themselves one fungicide spray with the early production system.”
Looking to the future, Delaney says Roundup Ready II soybeans will be available on a very limited basis this year. “There will be about 1,000,000 million acres in the United States. There’s no real change on the herbicide label. Monsanto reportedly has been able to link some genes so there will be more seed per pod, increasing the proportion of three-seeded pods. Also, LibertyLink will have about 1,000,000 U.S. acres this year of its soybean variety with resistance to Ignite herbicide. It looks good on broadleaf weeds, but it’s a little weak on grasses, particularly once they grow to some size.”