(upbeat music)
-: Okay, my name is Jim Specht,
a Professor in Agronomy, now retired
at the University of Nebraska,
and my specialty was Soybean Physiology and Production
in addition to Genetics Genomics,
but today we're gonna focus on physiology
in production of soybeans.
And, what we're gonna do is discuss yield-increasing
soybean production practices that we did not know about
in the past, and then we're gonna talk about the impact
of a cover crop when it's inserted into,
say a corn-soybean rotation,
the impact that cover crop will have.
Okay, so the first thing we're talking about today
is, we have six items on the list,
the last one will be covered by Steve Melvin,
and, he will go to his slide set for that.
But we're gonna talk about advancing your planting date
towards late April, early May,
as a good way to increase your soybean yield.
So let's talk about that.
Here you see on this slide are two pictures,
one taken in 2003, one taken in 2004
just after the summer solstice
which is the longest day of the year,
which is June 21st in most years.
You can see some plot signs there indicating
late April mid May, late May and mid June planting dates.
You can see the color change from green to brown there
as we delay soybean planting.
You also know that I put in red, blue, green
and brown lines there because I'm gonna use those colors
when I describe the data that comes off of planting dates
that are made on those dates.
We'll talk about the items at the bottom slides
down to the slide, where we'll talk about the items
at the bottom of each picture coming up here
and we'll deal with those issues then.
Now, get right to the bottom line,
this work was done back in 2003 and four
showed that there's a definite advantage
of early soybean with yields.
So we have seen yield on the left axis
and the planting date on the bottom axis.
And here on the top of the chart,
you can see the actual monthly days.
What you see there is the red line
representing the late April early May planting date
all the way down to the brown line that was shown
on the prior picture slide.
And what you see here is that soybean yield declines
as you plant it later in the season.
And you can see at the top part of the slide,
it was about five eighths of a bushel
per acre per year for the 2004,
and for 2003, it was a little bit less.
And we'll talk about the reason for that later too.
Now this has been confirmed in other studies.
Dr. Patricia Grassini working also
at the University of Nebraska,
showing this applies both to the Southern Nebraska
and Northern Nebraska and it applies more
to irrigated fields than it does to rain fed fields
because rain fed fields can be subject to August stress
which reduces their response to early planting.
So you can see on our left axis, you can see the yield
on the bottom axis, the planting date.
So it range from this case from a half a bushel
to three quarters of a bushel per acre
in different parts of Nebraska.
The study has been examined also at the national level
and at the north central region,
Dr.Grassini and his colleague Shawn Conlin in Wisconsin,
conducted a series of surveys and identified regions
in each State that are very similar
in climate, soil, and weather.
And what they found there is when they take
those individual regions which they called
technology exploitation zones, and what they discovered
was that planting date declines in all of those 10 regions,
except perhaps for rain fed Nebraska.
But if you look on the right side,
you see they found the reason for that
is there's ready response to early planting
with irrigated fields because there was no not likely
to be any water stress in August during the pod setting
period which is from our three to our five.
As you go left you have less water available
during that pod setting period,
and most dry land TEDs in Nebraska.
And so if you even look down on a greater detailed scale
on our sub TEDs in Nebraska,
and someone elected those and sorted those
into high yield and low class and high yield and low yield,
thousands of each of those TEDs, what he found
was that soybean planting was about seven days earlier
in the high yield plots than it was in the low yield plots.
So, if you wanna know more about this particular project,
it's available online through CropWatch,
you can go there and see.
If you don't happen to be from Nebraska,
you can go there and see the details there
but if you happen to be in Nebraska you can see more detail.
So, the planting date and soybean yield take-home points
for this part of the presentation,
is that there is a yield penalty
for delaying soybean planting in Nebraska after May 1.
It will generally average about 0.5 bushels per day,
or about 3.5 bushels per acre, per week of delay.
And it's greater in years when the yield potential
is greater, that is to say where you don't have
any water stress in August,
and an irrigated field is always likely to respond
better than a dry land field.
So, take home point here is if you have both irrigated
and dry land fields, plant your irrigated ones first.