Does It Make Sense To Plant So Early?
URBANA, ILL.
Reports are starting to
come in of fields planted
by mid-March in central
and southern Illinois. Though
there have been some fields
planted this soon in the past,
this is the earliest we have
ever had good planting conditions
across so much of the
state, and it’s certain that we have never before
had this many corn acres planted so early.
With the warm weather continuing, we expect
the crop planted now to get off to a fast start. It
takes about 115 growing degree days (GDD) to
get corn plants to emerge after planting. Highs
of about 80 degrees and lows in the 50s mean
that we are getting 15 to 18 GDD per day, so we
might see emergence within about a week if it
stays this warm. Some fields planted very early
have already emerged.
Even with the good conditions and perhaps
the pressure of seeing a neighbor planting,
many producers are still waiting to plant. For
many, the chance that the weather will turn
more normal – average lows in the 30s and
highs in the 50s through early April – simply
means that chances for problems are too great
and that cool periods or even frost could slow
growth or even kill emerged plants.
Soil temperatures are in or near the acceptable
range for planting in central and southern
Illinois, and at least with the weather this week
they are still increasing. If this were two weeks
later we would have a lot of people planting fast.
If it stays warm and doesn’t get wet, we normally
would expect planting to get going in late
March, with April 1 being the “go” date for many
in the southern two-thirds of Illinois.
We have never planted corn in planting date
trials as early as mid-March, but planting in
late March or early April has almost never produced
higher yields than planting in late April.
Of 12 trials conducted over the past three years,
corn planted in late April has yielded more than
corn planted in late March or early April nine
times, and the earlier planting has yielded more
three times. The average advantage from planting
later was about 4 bushels per acre. After late
April, of course, yields declined with further delays.
Planting date responses are notoriously unpredictable,
and so it’s not at all certain that
corn planted on March 15 or 20 will yield less
than corn planted the second half of April. If it
stays dry into the season, early-planted corn
may tap more soil water than later-planted
corn. But GDD accumulations are low in March
and April in normal years, so unless temperatures
stay high, early planting won’t necessarily
mean very early pollination, maturity, or harvest.
The biggest danger for corn planted so early
would be a return to low temperatures or even
frost after the crop has emerged. We are working
with a relatively short seed supply due to
low seed yields this past year; this could, should
replanting be needed, mean taking inferior hybrids
or even being unable to get enough seed
for a replant. Replant seed is also somewhat
costly – some companies charge less than full
retail for replant seed but might require planting
on or after a certain date before making that
discount available. Crop insurance may also be
an issue.
For many producers, it will make sense to get
fields ready to plant but hold off on planting
until the calendar turns to April. Unless temperatures
remain far above normal over the next
month or more, the risk of planting now may
well outweigh the likely return. But for those
who want to be able to say that they planted
corn earlier than ever before – and before their
neighbors – 2012 is providing the chance. Δ
DR. EMERSON NAFZIGER: Professor, Research
Education Center Coordinator, University of Illinois