Did Weekend Rain Wash Away Corn and Soybean Stands?

( Sonja Begemann )

The weekend torrential downpour across much of the U.S. might have you worried. What does it mean for planted corn and soybeans? How long do corn and soybeans survive underwater? What does it mean for nitrogen in soils? Will crusting become an issue?

“Locally, we have a lot of ponds and ‘bathtub’ rings to deal with,” says Farm Journal Field Agronomist Ken Ferrie. For ponded areas, Ferrie says temperature is a critical consideration as to whether or not the seed or seedling will survive underwater.

“I’ve seen corn and beans survive underwater in cold soils for six or seven days,” Ferrie says. “In warm soils, they can be in trouble within 48 hours.”

If you’re in an area where temperatures are expected to hit or exceed 80 degrees, the crop is less likely to survive. Once water recedes, be sure to scout.

When you’re scouting emerged fields, Ferrie reminds farmers that it’s not just a simple stand count—you’re looking for how many ears you’ll get per acre.

“Anything that’s more than one collar behind is not going to put on an ear,” he says. “But we have time to fix these fields instead of settling with something that’s going to give us a 60% to 70% ear count.”

As you’re scouting, keep an eye out for crusting—especially in soybean fields. The plants might need help getting through, so don’t let the crust get too hard before running the hoe.

“While I would focus on unplanted acres before I worry about replanting a pond, I would take time to run a hoe to keep us from replanting or losing some of that early planting advantage on beans,” Ferrie adds.

Nitrogen watch outs

The lifeblood of corn, nitrogen, is prone to leeching and recent rainfalls leave many farmers concerned about whether the crop will have access to the critical nutrient or not.

“This depends on how the program was applied and when it went on,” Ferrie says. He’s not worried about anything spring applied or applied with the planter—don’t expect much loss regardless of the form.

Fall applied nitrogen, on the other hand, is the greater risk.

“In our fall-applied inhibitor plots, we checked them April 16, the fall nitrification strips were 80% still in the ammonium form,” Ferrie says. “This week’s testing isn’t back yet. Without inhibitors [the anhydrous] was 90% converted to nitrate and subject to loss.”

You should also watch winter applied AMS closely as it could have moved deeper into the soil. Because the rain came slow and limited erosion, nitrogen likely moved deeper into the ground instead of out of fields. It might not be available to corn during the carbon penalty if it’s too deep.

“I don’t think it’s lost,” Ferrie says. “The N needs to be near the surface, that top two or three inches, two to three weeks from now when the carbon penalty starts.”

Read more Boots in the Field Reports here:

Boots in the Field: Banding Vs. Broadcast Nitrogen Efficiency