Will Corn Following Corn Face “Issues” In 2011?
URBANA, ILL.
The 2010 season was one
of the most disappointing
in years for corn in many
parts of Illinois, with the
statewide average yield only
157 bushels per acre, just 4.2
bushels higher than the U.S.
average and the third-worst
yield in the past decade. Over
the past 10 years, the Illinois corn yield has averaged
13.7 bushels per acre above the U.S. national
average and has been below the national
average only once (by 4.9 bushels in 2005) and
above it by as much as 25.1 bushels (2008).
The major problem in 2010 was heavy rainfall
in June that resulted in standing water and saturated
soils, which in turn resulted in nitrogen
loss and damage to root systems that could not
be repaired. As a result, affected fields and parts
of fields ended up with shortages of both nitrogen
and water, problems made worse by high
temperatures and early maturity, and in some
cases by dry weather during the latter part of
the grain-filling period.
Corn following corn was particularly hard-hit
in 2010, and there were numerous reports of
larger yield penalties than most have seen for a
number of years for corn following corn compared
to corn following soybean. We saw the
same thing in our research trials, where we
have been comparing continuous corn, corn rotated
with soybean, and corn following either
corn or soybean in a 3-year corn-corn-soybean
rotation. This study was established in 2003,
and so 2008 was the fifth or sixth year of continuous
corn.
While we have found at some sites that the
yield loss in corn following corn or continuous
corn compared to corn following soybean has
generally been less in recent years than the old
10 percent rule of thumb, we have certainly
found little evidence that this yield penalty has
gone away (Table 1). Across four northern Illinois
sites, this penalty for continuous corn was
about 11 percent in 2008-09 and 19 percent in
2010. We did find that second-year corn in the
corn-corn-soybean rotation yielded only 5 percent
less than soybean following corn in 2008-
09 and 10 percent less in 2010, indicating that
having soybeans recently in the rotation does
help to lessen the negative effect of having corn
as the previous crop. At the two southern Illinois
locations, with considerably lower yields,
the penalty for continuous compared to rotated
corn was substantially less, measured either as
bushels or as a percentage.
I provided in an article last fall some of the
reasons that corn following corn did so poorly
in some areas in 2010. In certain ways it was a
“perfect storm” of problems, resulting from lots
of well-preserved residue, cool temperatures for
several weeks after planting, considerable soil
compaction, very little opportunity for spring
tillage, and marginal seedbed conditions, followed
by the large amounts of rain in May and
June.
Does the relatively poor performance of corn
following corn in 2010 mean that we should
worry that 2011 will show similar results? Most
indications are that this shouldn't be our expectation.
Most importantly, field and soil conditions
as we head into 2011 are much different
than they were a year ago. None of the
factors of a year ago – late fall harvest, poor
tillage conditions, lots of fresh residue on the
surface, and much nitrogen yet to apply – exist
this spring. I do not believe I have ever in my 30
seasons in Illinois seen the state as “tilled up”
going into the spring as it is this year. For certain,
if tillage can solve our problems, we can
consider them solved as we head into this season.
One additional benefit is that it has not
been wet for extended periods when soil temperatures
were warm since nitrogen was applied,
meaning that most of the nitrogen we
applied last fall should still be present, with a
good deal of it still in the ammonium form and
so not subject to loss.
Though we can certainly feel good about
preparations we've been able to make for this
spring, we know from history that a good fall
doesn’t always mean a good crop the following
year. While the fact that soils are starting to dry
out nicely in some areas of the state is a good
sign as we head into April, we need to be careful
not to undo the compaction relief provided
by last fall’s tillage by driving on soils before
they’re dry enough. We know that any driving
we do on soils this spring will do some compaction;
soils are typically at or near field capacity
when we’re ready to plant in the spring,
and it’s at field capacity that they are most subject
to compaction. Waiting until soils are dry
enough at depth (not just over the surface) will
help minimize compaction effects, as will using
controlled traffic, making fewer tillage passes,
and lowering tire pressure.
Because we had some 3 million more corn
acres than soybean acres in 2010, and we grow
less than a million acres of crops other than
corn and soybean, we know that some 20 percent
of the corn acres in Illinois in 2011 will follow
corn, providing corn acreage doesn’t drop
from 2010. With high corn prices and a lot of nitrogen
already applied, such a drop seems unlikely.
So should we change anything for corn following
corn this year? No. Our research shows
that both respond similarly to planting date and
to plant population, so those should change
only as soil conditions and productivity might
indicate. We’ve never been able to identify hybrids
that do consistently better in corn following
corn, though corn following corn may tend
to experience stress (primarily drought stress) a
little more often, so that should be factored in.
Diseases related to residues can also be more of
a challenge. And corn following corn typically
needs a little more nitrogen – see the N Rate
Calculator for current numbers.
The important things-having good soil conditions
where the seed is placed and good rooting
conditions underneath the surface-are critically
important for corn no matter what the previous
crop. And the crop needs to be well supplied
with nutrients and protected from pests. Once
we cover these basics, the crop will respond
mostly to weather factors – water and temperature
– that we don’t control. That has always
been true, and will be true again in 2011. Δ
DR. EMERSON NAFZIGER: Professor of Agronomic
Extension, University of Illinois