The greatest losses in corn yields, in continuous corn rotations, occur in high-yielding environments. Iowa State Extension Agronomist Roger Elmore compared the same corn hybrids across 26 Midwestern locations and found a 0-30 bu. advantage for corn following beans compared to corn following corn. On average, continuous corn yields suffer a 9% yield drag over those rotated with soybeans, he says. Stacked hybrids with insecticide treatments can help to mitigate these losses, he says.
Hybrids selected for continuous corn rotations need to offer good seedling vigor, disease resistance, stalk and root health, insect resistance and overall stress tolerance, Elmore advises.
He offers the following advice for continuous corn rotations:
- Later planting dates work best.
- Learn how to handle the residue.
- Avoid compaction.
- Furrow closing problems will increase. Don't plant into wet seedbeds.
- Select better drained soil for continuous corn.
- On average, you will need a 60-lb./acre nitrogen increase over corn following beans.
Farmers with ultra high corn yields, the kind you read about in yield contests, have the following practices in common, Elmore says:
- High management.
- Great locations.
- Higher plant populations.
- Low plant stress.
- Scouting 4-5 times daily.