June 3, 2022
What’s the first challenge in growing 70 bushels of soybeans per acre? While you may expect a profound answer, a somewhat cynical agronomist might say getting beans emerged above ground in a uniform stand is job No 1.
Even after a century of growing soybeans, emergence through crusting soils is still an important hurdle. If you could plant in dry soils, then pencil in a rain several days later to soften any crust, you could stop worrying about soybean emergence. But in the real world, that’s still a realistic hurdle, whether final yield potential is 50 or 75 bushels per acre.
“Crusts can form, which make it hard for soybeans to break through,” says Steve Gauck, a regional agronomy manager for Beck’s, based near Greensburg, Ind. “We think of it being more of a problem in conventional tillage, but it can happen in no-till fields, too — especially on silt loam soil types planted wet.”
Beck’s sponsors Soybean Watch ’22. Gauck makes a habit of visiting soybean fields soon after they emerge so he can assess stands. The Soybean Watch ’22 field was not yet planted at press time, but he has observed other fields already.
Crusted soils are one issue Gauck finds that can hinder emergence. Soybeans have lots of pushing power, especially if several seedlings along a row attempt to emerge at once. However, if the soil is so hard a seedling can’t push through, the neck that pulls cotyledons up through the soil may break. If a plant’s neck breaks, the plant will die.
“We need to anticipate when rains might come when we’re preparing fields and deciding how much to work the soil,” Gauck says. “It’s also important to see if the planting process is creating sidewall compaction in the seed trench. That can happen in both no-till and conventional planting, and it can make it more difficult for seedlings to navigate their way through the soil.”
However, many other factors can influence emergence, Gauck says. These include diseases if soybeans stay in the soil too long before germinating and emerging, plus feeding damage by insects and slugs.
In no-till situations, if the new row winds up over an old corn row, residue may interfere with obtaining good seed-to-soil contact, which can interfere with proper emergence. Likewise, if disc openers are dull or worn beyond proper limits, seed may not be placed at the proper depth, or it may be more likely that residue can wind up in the trench, in a process called hairpinning. That can also interfere with emergence.
So, what if crusted soils take their toll, diseases and/or insects snatch a few plants, and some seeds simply don’t germinate? How many plants do you need for good yields?
“I’m satisfied if there are 80,000 plants per acre as the final stand,” Gauck says. “That assumes that there aren’t large gaps within rows, and that you can still control weeds.
“If you’ve got 80,000 plants per acre, you can still obtain full yield. In fact, with modern varieties, some of Beck’s Practical Farm Research data indicated you could accept stands as low as 70,000 in some cases rather than replant.”
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