Wheat Producers Facing Tough Call on Nitrogen Application
Even after receiving rain, Oklahoma wheat producers can still face tough decisions
about if, when and how much to fertilize as they enter spring, the critical juncture
of the growing season.
The good news is producers still have time to act. However, if producers battle an
extremely dry fall and winter with a small window for fertilizer, Oklahoma State University
Extension experts said there are three feasible scenarios.
In cases where there is good plant stand overall, producers should evaluate the crop’s
current yield potential, which could still be decent, and apply enough nitrogen to
achieve it.
“With the rain and some sunshine, these plants will start growing again. For producers
who use N-rich strips, if your field needs nitrogen, it should show up,” said Brian Arnall, OSU Extension precision nutrient management specialist.
Under a second scenario that could play out principally in southwest Oklahoma, some
fields may be experience uneven growth with a combination of already established wheat
and wheat that has only started germinating and emerging.
If producers decide to keep the crop, will the newly emerging plants still have enough
exposure to cooler temperatures to switch from vegetative growth to reproductive growth,
and if so, what is the crop’s yield potential overall?
“This is where it gets complicated, when we bring it back to the question of nitrogen
management,” Arnall said. “This is going to come down to producers closely assessing
their stands and the yield potential of their crop. I think in most cases those newly
emerging plants will switch to reproductive growth and put on a head. However, those
plants will be delayed in their development, and the amount of grain produced by those
heads will likely not be close to full potential.”
When assessing a field’s grain yield potential, a general rule of thumb is 60 to 70
tillers per square foot are needed to maximize yield. Dryland production in southwest
Oklahoma and the Panhandle can lower that number to 50 to 60 tillers per square foot.
“If you have half or less, that’s not a positive sign for taking the crop to grain.
If you’re a cattle producer just wanting to graze out, that may be enough for you
to keep the stand,” Arnall said. “It comes back to your objective. If you decide to
keep the stand in this case and apply nitrogen, consider lowering the rate from your
normal application.”
Meanwhile, in a third scenario in far northwest Oklahoma in drought, plants coming
out of winter dormancy will begin growing.
“If there’s no water there for those plants, they’re going to quickly go backward
and eventually die,” Arnall said. “Producers should have their N-rich strips down
in case it does rain soon, but most are likely hesitant to spend money to apply nitrogen
to their fields if there’s little to no yield potential.”
For more information on wheat crop management strategies, contact the nearest county OSU Extension office or download free OSU fact sheets on the topic, including Estimating Wheat Grain Yield Potential and Wheat Grazeout versus Harvest for Grain.