Double-cropping soybeans after wheat provides the opportunity to harvest two
crops in the same year from the same piece of land. But here are challenges and
concerns with double-cropping, and a University of Missouri Extension agronomist
says location is a big factor.
“In the middle part of Missouri we’re going to be planting soybeans around
July 1, but is there enough time for the soybeans to mature before the first
frost?” said Bill Wiebold. “In this part of the state, probably, but as you go
farther north the growing season shortens just enough that by the time you get
to the Iowa border it probably doesn’t pay to double-crop.”
Conversely, as you move farther south in Missouri double-cropping becomes
more likely to succeed. Wiebold says that in the southeastern part of Missouri
where quite a bit of wheat is grown, almost every acre is double-cropped with
soybeans.
Double-crop soybeans don’t typically yield as high as full-season beans,
but with recent high soybean prices it can still be very profitable. However, if
you lose too much yield on the soybean side, you have to make it up on the wheat
side. Wiebold says that can be difficult because wheat prices haven’t followed
the same trend soybeans have taken.
“It’s a complex equation between what happens to the wheat and what happens
to the soybeans,” Wiebold said. “What are the different prices? What kind of
yields can you get? So it’s a little complicated and it becomes even more
difficult north of Highway 36.”
Aside from the length of the growing season, there are other considerations
when double-cropping, such as straw management.
“The wheat is going to produce straw. You can bale it, and that’s another
source of revenue if you have a place to sell that straw,” Wiebold said. “You
have to be careful, though. If you wait a couple days to plant, that could hurt
your bean yield. So you have to calculate that into the equation.”
Another challenge is that double-crop beans are planted at such a time that
seed filling will occur in late August, when the day length is shorter and the
angle of the sun is greater, so there is less sunlight and less yield
potential.
“You also get a shorter seed-filling period,” Wiebold said. “It may be 35
days versus 55 days for full-season.”
Moisture is also a crucial factor when it comes to double-cropping.
“The length of growing season is about location,” Wiebold said. “But
wherever you double-crop, wheat has taken quite a bit of moisture out of the
soil. So what is that weather going to be—not only the day that I plant but also
the next six or seven days as I’m trying to get those soybean seedlings out of
the soil? Quite often it is just too dry and the beans don’t emerge or they
emerge spotty.”
Wiebold says some practices that can make double-cropping successful
include having a high-yielding, early-maturing wheat variety, no-till planting,
planting as early as possible, using narrow rows, and increasing seed
density.
“No-tillage is a good water-conservation practice and it’s a good
time-conservation practice,” he said. “Narrow rows are important because that
canopy forms more quickly, capturing sunlight sooner and helping yield.”
Wiebold recommends selecting a soybean variety that you would use in a full
season, so it is tall enough and produces enough leaves to drive the yield. He
also says a higher seed density is needed when double-cropping.
“If we have 100,000 to 110,000 plants per acre, that captures most of the
yield in full-season situations,” Wiebold said. “But you may need 140,000 or
150,000 plants in a double-crop situation. The plants are shorter; they don’t
produce as many nodes, so you have to add some plants to make up for those
nodes.”
For more information, contact your local MU Extension center.
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