Columbus, Ohio
February 19, 2007
Crop rotation is the key to
maximizing yields while reducing potential problems with insect
and diseases. However, some Ohio growers are willing to accept
the risks of continuous corn production in the hopes of
capturing more profit from higher corn prices.
Peter Thomison, an Ohio State
University Extension agronomist, is encouraging growers to
follow key management practices to help reduce the risks under
continuous corn production.
“Many agronomists do not recommend continuous corn. Corn grown
following soybeans typically yields about 10 percent more than
continuous corn,” said Thomison, who also holds a partial
research appointment with the Ohio Agricultural Research and
Development Center. “Additionally, growers face many challenges
with corn following corn, and they need to be aware of the
issues involved with the production practice.”
The biggest issue under continuous corn production is the large
amount of residue that is generated. That residue can result in
a variety of planting and harvesting problems, including:
- Greater levels of disease
inoculum. Continuous corn increases the frequency and
severity of disease problems.
- Cooler, wetter soils
during and after planting, which result in delayed
germination and emergence, slower vegetative growth,
prolonged exposure to diseases and insects, and compaction
during harvest.
- Interference with planter
row units. The presence of residue from previous corn crops
may cause uneven seedling depths and poor seed to soil
contact.
- Decreased efficacy of
soil-applied herbicides.
- Increased stand
establishment problems due to slow warming and drying of
soils, especially those poorly drained.
- Greater potential for
nitrogen losses.
“The risk and magnitude of yield
drag and other problems associated with continuous corn is
greatest with no-till,” said Thomison. Other problems include a
greater risk to western corn rootworm and longer harvest season
due to time and capacity demands on machinery, drying
facilities, transportation and storage.
“The longer corn sits in the field, the greater the risks to
lodging, stalk rots and other diseases,” said Thomison.
For growers who intend to plant corn following corn or switch
part of their soybean crop to corn production, several
management practices can be followed that may reduce the risks
and minimize potential yield losses.
Such practices include:
- Planting corn on the
most fertile, well-drained soils to reduce stress and
maximize yield potential. “Avoid droughty soils, as well
as poorly drained soil conditions,” said Thomison.
- Developing strategies
for dealing with increased crop residues. Use stalk
chopper and knife rolls on combine heads; spread residue
uniformly during harvest; consider strip tillage and
avoid no-till where practical; avoid no-till planting on
top of old rows; and use row cleaners and seed firmers.
- Managing corn diseases
by selecting hybrids with good disease resistance,
emergence, and seedling vigor. “Burying crop residue
reduces disease pressure, but may be of limited value if
neighboring corn fields are no-till,” said Thomison.
- Reducing insect risks
by planting Bt rootworm hybrids, or using seed/soil
insecticides. Scout fields for cutworm and army worm
damage.
- Adjusting nitrogen
rates. “Optimum nitrogen rates for corn after corn are
generally higher than those for corn after soybean, and
range from 30 to 50 pounds of nitrogen per acre,” said
Thomison.
- Following standard
weed management recommendations.
- Scouting fields during
harvest to detect stalk lodging and stalk rot.
Prioritize those fields with problems for early harvest.
“The decision to switch to
continuous corn should be made carefully. Continuous corn
production requires a higher level of management to achieve high
yields,” said Thomison. “Although short term economics may favor
corn after corn, each operation is different, and understanding
the risks associated with corn after corn is the first step
toward managing the practice wisely and economically.”
For more information on managing continuous corn, log on to the
Ohio State Extension Agronomic Crops Team Web site at
http://agcrops.osu.edu.
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