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The earlier you harvest wheat and plant soybeans, the better off you’ll be with yields.

Chris Torres, Editor, American Agriculturist

June 22, 2020

3 Min Read
Close up of soybeans planted soon after wheat harvest
DOUBLE-CROP DECISIONS: Getting soybeans planted soon after wheat harvest is key to getting a good yield. Del Voight, Penn State Extension agronomist, says to plant at high populations, in narrow rows and with full-season varieties. Holly Spangler

If you’re double-cropping soybeans after barley or wheat, there are some important things you need to remember.

It takes soybeans 90 days to develop pods and dry seed. Depending on the area you live in, getting soybeans in the ground as soon as possible is crucial to avoid fall frost.

Del Voight, Penn State Extension agronomist, has done extensive research on optimum planting dates and seed populations for double cropping. It’s all about planting at higher populations in narrower rows and, for the most part, using full-season varieties.

He has some tips for getting a crop going after wheat:

High populations. Plan to establish at least 180,000 plants per acre. To do this, raise the seeding rate to 200,000 if planting before July 5 and at least 220,000 if planting after July 5 to ensure ideal canopy cover.

Narrow rows. Plant rows less than 15 inches — 7 inches or less is preferred — because there is less time for the soybeans to gain height to pod. Narrow rows allow for more beans to grow at higher populations.

Weed burndown. If the field has visible weeds, burn down to ensure weed competition is kept to a minimum.

Economic target. Set a realistic economic target. Double-crop soybean yields of 30 bushels an acre is not out of the question, and depending on the price of soybeans, there may not be much room to spend on input costs in getting the crop going.

Yield potential. How will planting affect yield? Voight has put together a table to illustrate the effects of planting date on yield response. Simply put, the sooner you get the crop in, the better the yield potential.

Table shows planting date’s impact on yield potential

First frost. Depending on where you farm, hitting the fall frost date is always possible, so keep your options open on using soybean as a forage. Check out this first frost map for Pennsylvania as a guide. If so, sorghum sudangrass or another annual crop may be a better selection.

Full-season soybeans. In research done in Lancaster County, Voight says that full-season soybean varieties out-yielded shorter-maturity varieties in most seasons.

The most important thing to remember, Voight says, is to plant a maturity group that can grow as long as possible in the vegetative stage to gain height before flowering, allowing the canopy to fully close.

Alternatives to soybeans

Maybe you’re in an area where first frost will make it difficult to get the double-crop soybean harvested in fall, or maybe you want a good forage crop.

If this is the case, then sorghum sudangrass is a good option after wheat or barley, according to Tom Kilcer of Advanced Ag Systems LLC in Kinderhook, N.Y.

Sorghum is also a good alternative for grain, though soybeans, will bring a better return on investment, Voight says. If you’re looking at forage, sorghum sudangrass or forage sorghum are good alternatives.

“This is all depending on when harvest is complete,” Voight says, adding that harvesting high-moisture wheat — usually around 20% or more — and then planting the soybeans soon after is key to boosting yields.

“Beyond that, leaving it fallow for a month [and] then establishing grass hay or alfalfa works great,” he says.

Kilcer has another option if you’re looking at forage.

“Perhaps a better option is a heavy manure application with immediate incorporation to capture all the nitrogen. Beginning of August plant 100 pounds of oats per acre, preferably a variety with good rust resistance, and 80 pounds of triticale. Both should have treated seed,” he says. “The oats are harvested at flag leaf stage about the end of September. It is critical that the mower be set to cut at 4 inches. If you cut shorter you will wipe out the triticale. The triticale will regrow after the oat harvest and give another crop the next spring. 

"The fall oats are phenomenally high digestibility. If you don’t want the triticale, you can use just oats in the system.”

About the Author(s)

Chris Torres

Editor, American Agriculturist

Chris Torres, editor of American Agriculturist, previously worked at Lancaster Farming, where he started in 2006 as a staff writer and later became regional editor. Torres is a seven-time winner of the Keystone Press Awards, handed out by the Pennsylvania Press Association, and he is a Pennsylvania State University graduate.

Torres says he wants American Agriculturist to be farmers' "go-to product, continuing the legacy and high standard (former American Agriculturist editor) John Vogel has set." Torres succeeds Vogel, who retired after 47 years with Farm Progress and its related publications.

"The news business is a challenging job," Torres says. "It makes you think outside your small box, and you have to formulate what the reader wants to see from the overall product. It's rewarding to see a nice product in the end."

Torres' family is based in Lebanon County, Pa. His wife grew up on a small farm in Berks County, Pa., where they raised corn, soybeans, feeder cattle and more. Torres and his wife are parents to three young boys.

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