Before adding an extra year of corn into your farm’s crop rotation, consider these important facts.
Yield impacts
Typically, second-year corn yields 6 percent to 10 percent less than first-year corn, Ohio State Extension economist Barry Ward says. If the crop is not grown in highly productive soil, the yield loss could be even higher.
Higher nitrogen inputs
Growers will have to apply more nitrogen to second-year corn because of the nutrients normally made available by soybeans in rotation would be lost.
Ward and Penn State agronomist Gregory Roth both estimate that an additional 30 pounds to 50 pounds of nitrogen would be needed per acre in a continuous corn situation.
Crop protection
Farmers need to be aware of the increased pest pressures caused by continuous production. Growers may be faced with additional fungicide and insecticide costs for rootworm control and disease pressures.
Rootworms chew off the roots damaging the plant’s productivity. In some cases, it can completely kill the plant. The rootworm is a potential problem in continuous corn production and the risk increases with each subsequent year, according to experts.
Roth says to consider each particular field’s history when it comes to rootworm before deciding to plant corn after corn.
Disease threat
Several diseases can be more active in continuous corn production as well, particularly diseases caused by pathogens that survive on crop residue or in the soil. Tillage practices can reduce levels of inoculum, but crop rotation is a key management practice as well.
In the absence of rotation, susceptibility to disease should be carefully considered when selecting a hybrid.
Management challenges
Ask yourself if you have the financial capacity to make the switch, said Ward. Corn takes more money upfront to get planted, and takes more time, labor, and equipment to manage than soybeans.
Some factors growers should consider include increased combine capacity and machinery costs; more manpower and trucking at harvest; and more storage and drying capacity.
Extra field time
With continuous corn production, extra field time may be required to scout for insects and diseases. If insects or disease are found, producers may be faced with having to rotate that field into another crop for one year, or the costs of soil insecticides, a Bt seed variety or seed treatment.
Any volunteers?
Corn itself can prove to be a nemesis in continuous corn production, according to Kentucky weeds specialist Jim Martin.
It can be a particular challenge if the volunteer corn is a glyphosate-resistant hybrid because it reduces the options farmers have to kill it, he said.
Volunteer corn is likely to sprout and grow in clumps, and these clumps can crowd out and compete with other seedlings. One clump per 8 square feet that is not controlled within 10 weeks of emergence can cause 25 percent yield loss.
In fields with severe volunteer corn, the best option for control is to rotate that field into another crop, Martin said.
