The Rural Voice, 1986-10, Page 22PALE CORN
SYNDROME
by Mervyn Erb
Ross McBeath told me a few
months ago that what we need
are more humorous and light-
hearted articles in these gloomy
and uncertain times. I wish I
could say that the good news is
that the bad news is all wrong.
But I can't. There are a number
of problems I see with this year's
corn crop and I'd like to discuss
them, as I'm sure there will be
plenty of questions once the com-
bines pull into the fields. My
apologies, Ross.
Around September 1 it was evi-
dent that the corn had run out of
nitrogen. "Fired up" leaves, pale
corn and premature death were
evident in three-quarters of the
fields. As we had been through
many fields in the last week of
July, the dramatic change was
startling. Corn with adequate
rates of N was poor and unthrifty
looking. Only those fields with
very high rates (185 N) appeared
to have satisfactory colour.
While attending an agronomic
seminar in Chatham on Septem-
ber 9, I was told by the two
Western Ontario Pioneer seed
corn agronomists that they were
being run off their feet with calls
from growers describing "pale
corn." Many fertilizer dealers
echoed the remark. That evening
on the way home we kept our
eyes open and stopped at many
fields throughout Kent and
Lambton counties. On the whole,
they didn't look any worse or any
better than our local fields. Once
you got into the fields, past the
outside rows, it was obvious that
the corn had run out of fuel.
Nitrogen loss occurs through
volatilization, denitrification,
leaching, and mineralization or
immobilization. This phenome-
non occurs every year. As a mat-
ter of fact, nitrogen utilization is
only somewhere between 50 to 70
per cent. The question is why is
the utilization rate down this
year, or where did we lose the
nitrogen?
I could understand high losses
in Essex, Kent, Lambton, Middle-
sex, and South Huron. These
areas had high amounts of rain-
fall this past spring and summer.
The west half of Elgin County
was again badly hit. However,
rainfall rates between the Grand
Bend - Staffa, Goderich - Kin -
burn parallels weren't excessive or
really over the six-year norm.
My rainfall chart doesn't show
any deviation from the norm, ex-
cept in July. We collected 11/2 in-
ches from July 12 to July 18 and
another 21/2 inches on July 25.
The total July accumulation of
4.1 inches is the highest on my
records, being beaten only by
July of 1980, when 4.6 inches
fell. Looking through my records,
I can pretty well safely say that
the drier the July and the wetter
the August, the better the corn
yields. June didn't have one rain-
fall over 1' inches; however, it
did rain 9 times throughout the
month and 13 times between May
21 and June 27. I'm sure this
kept the roots from going deep.
Granted, none of these rainfall
rates would cause leaching or the
flushing of the nitrate N out the
tile. Our losses probably occurred
through denitrification and im-
mobilization. As you quite likely
remember, plowing was no fun
last fall. We all remember muck-
ing the combines, trucks, trac-
tors, grain buggies, and plows
through the fields. Upon doing
many compaction assessments us-
ing penotrometers and digging
plenty of holes in corn fields this
past summer, it was evident that
most of the fields (except those
on sand) have a three-inch com-
pacted zone at around the seven
to nine -inch depth. This com-
pacted layer is made up of
blocky, massive, structureless,
dried-up mud. In a few words,
that's just how it appeared, what
with the combination of the
severe beating it took last fall and
the abuse it took this spring.
I realize that spring came early
again this year, but there was a
difference from the spring of
1985. Soil temperature readings
on April 29, 1986 were 3°F colder
than those on the same date in
1985. And the readings were in
the same field both years.
This year we also had more
water held in the soil and poorer
internal drainage because of the
mess last fall. Not only did we
not see corn roots go any lower
than those heavily compacted
areas at the seven to nine -inch
depth, but water will not readily
move through such a tight zone.
Because of this, most of our rain-
fall evaporates out of the soil in-
stead of moving down to the sub-
soil area to feed the crop through
hot dry weather. High amounts
of moisture evaporation result in
N Toss through denitrification.
The other problem with this
year's corn started on August 27.
That's the day summer ended in
my books. f, big rainfall and
then five consecutive nights of
cold weather, including two
nights of temperatures under
40°F. Corn or beans, but
especially beans (soys and
whites), will never regain their
photosynthetic rates if hit with a
full night of temperatures below
40°F. Combine this with a water -
saturated soil that is very low in
oxygen and you've got a shut-
down factory that respirates seed
weight away.
I had the good fortune to be
asked to judge field crops for the
Mitchell and Exeter agricultural
societies. After going through 62
different fields (most of them
corn), it was evident that many
varieties were respirating heavily
under their husks. Some were just
dripping wet. Those 100 and 105 -
day varieties are going to have
tremendous kernel weight loss
from being shut down so early.
The third unfortunate situation
we've got on our hands this year
is excessive corn -borer stalk
damage. In many fields it is ex-
treme and I expect stalk breakage
to approach the 50 per cent level
in those fields.
In case you're wondering how
the heat units ended up for the
year: May, June, July, and
August were all above the eight-
year average and better than in
1985. By the end of data collec-
tion, September 20. we ended up
with 2,798 CHU at CCAT — or
the worst year since 1979. We lost
everything after August 27.
Today as I write this, it's
September 19 and it's still rain-
ing. Keep your chin up, fellows.
Someone once said, "When the
going gets tough, the tough get
going." ❑
20 THE RURAL VOICE