Over the last four decades, Georgia’s average soybean yield has grown by 0.25 bushels per acre, topping out around 40 bushels per acre last year. “But I hear from growers who get stuck at 50 or 55 bushels and wonder what they can do to get more,” said Jared Whitaker, University of Georgia Extension agronomist.
Deep South growers can do better without throwing the kitchen sink at the crop if they’ll look at a few things differently when it comes to soybean management, “And I all but guarantee they’ll hit higher yields,” he said.
It’s no surprise irrigation is the single-most important factor to increase soybean yields in the Deep South, like in Georgia, but, again many growers are reluctant to spend the money to irrigate soybeans, he said.
“With irrigation, the trick is to manage stress throughout vegetative growth but especially just prior to and through bloom, which is when the plant’s water needs go up. When you talk about typical planting dates in Georgia, we often see as the crop progresses near bloom, 100-degree weather and dry soils. Pods are not going to set well in that situation and yields will just not be there if the plant is water stressed at that time.”
After a good stand is established, soybeans need one inch of water or better each week. At bloom to full seed, or R1 to R6, that requirement rises closer to two inches per week
For full-season determinate varieties, Maturity Group V or VI, he said, planting needs to be done by mid-May. After that, yield potential drops. Research shows yields drop half a bushel per day when soybeans are planted after May 10.
Two to get one?
It’s been said that you plant two soybean seeds to get at least one plant to emerge. Whether that holds in all cases, plant population does matter when it comes to yield potential. At least 100,000 plants per acre is a good number to hit. “And that can be variable across the farm. If that means planting 140,000 seeds or 170,000 seeds to get to that 100,000-plant stand, we can help growers figure that out on a field-by-field or farm-by-farm basis,” he said.
Row spacing? For full-season beans, 36-inch rows are fine, twin-row works, too. But if planting dates push into summer, the more narrow the rows the better.
Of course fertility matters and potash is important. And the soybeans should be inoculated to make nitrogen.
The growers who want to increase yields through a few extra steps need to protect those yields. Fungicide and insecticide applications can be worth the cost, he said. For example, spraying for loopers might run $10 or a bit more per acre. In this market, that is one bushel of soybeans, but that application can ensure your yield machine, or that soybean plant, isn’t too damaged to manufacture those yields for harvest.
In general, for soybeans to get the attention of traditional Deep South crops like a peanut or cotton, the crop needs to yield higher and payoff. The irony, or the catch, is soybeans first need to get that attention.
“There is no doubt because of the situation with other crops and prices not looking great (in 2015), if we can take somebody, and really no matter what their average (yields) have been, they can do a few things differently or think about soybeans in a different way, and bump yields up and bump them up considerably and make money,” he said.