Yellowish Stalks And Leaves Signs Of Nitrogen Deficiency
Corn Yield Should Have Been 520 Million Bushels Higher
JACKSON, MO.
Dr. Peter Scharf, University of Missouri Extension
agronomist and MU professor of
plant sciences spoke to Missouri farmers
about corn yield loss due to lack of nitrogen
during the 2009 growing season. Scharf
logged more than 2000 road miles in August
surveying the corn-belt and examined aerial
photographs of fields in Missouri, Illinois and
Indiana. Scharf saw field upon field with telltale
signs of nitrogen deficiency; yellowish
stalks and leaves.
Scharf explained the yield impact of this
year’s excessive rainfall in regards to nitrogen.
“There were some fields in this area and really
all over the Midwest, with substantial nitrogen
deficiency. Illinois was probably the
hardest hit, due to rain washing the nitrogen
away. Down here in southeast Missouri most
people side dress so from the time of the side
dress application to when the corn needs nitrogen,
it is less time and less rain. In a lot of
the rest of the state and in Illinois all of the
nitrogen was applied pre-plant so the nitrogen
is more vulnerable; there is more time for the
nitrogen to be lost before the corn needs it. We
had a lot of that this year. My estimate is 520
million bushels over the corn-belt, this includes
a little bit out of Arkansas and Tennessee but
mostly Illinois and Missouri and southern Iowa.
We could have made 520 million more bushels
of corn this year if we had not run out of nitrogen
– we had enough water to do it, we had
enough plants out there to do it; we did not have
enough nitrogen.”
“This is the first time that I have ever said
that, in southeast Missouri, we actually lost
yield. Normally, in a wet year, you might find a
field here or a field over there where they never
got the fertilizer on. But I have never seen
enough fields to show deficiency to say, ‘Okay
we actually, as a group, should have done
something better in this part of the state. We
needed to apply additional N to some of these
fields.’”
Scharf explained that growers had options.
“Even if growers do not have high clearance machines
in the field, aerial applications of nitrogen
would have helped. Down here there are
quite a few airplanes that are used to putting on
100 pounds of urea, which is 46 pounds of actual
N. It is a standard thing that they usually
charge six or seven dollars an acre for. It is just
not much money when you have got a problem.
For the service of flying, that costs hardly more
than driving through the field. You can do that
no matter whether the ground is soggy or not.
There also were plenty of days where growers
were spraying beans and they could have used
that equipment to put nitrogen on corn. But we
are not used to doing that with that equipment
at that time of year. There is a lot of equipment
out there that has clearance for corn and could
hold some nitrogen. A lot of those are sprayers
with smaller tanks and you have to fill them up
pretty often. That slows you down, but it gets
the job done and if you need the N you’re still
making plenty of money per hour.”
Scharf says spending an extra $30 per acre to
apply nitrogen using ground rigs or aerial applicators
would have produced up to 35 bushels
more per acre. He estimated that on average
southeast Missouri fields lost 15 bushels per
acre due to N deficiency in 2009, but some fields
were worse while others had little or no deficiency.
“Additional N will give you a yield bump
if you can see deficiency, but probably won’t if
you can’t see it.” Δ
Dr. Peter Scharf, University of
Missouri Extension Agronomist and
MU Professor of Plant Sciences
Photo by Betty Valle Gegg-Naeger