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Nitrogen Timing in Sorghum and Wheat
University of Nebraska – Lincoln
Dr. Brian Arnall looks at research results of nitrogen timing both sorghum and wheat.
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Hello. My name is Brian
and now I'm with Oklahoma state university.
My title is a precision nutrient
management extension specialist.
My job is to help producers,
and the people of the state,
with their nutrient management decisions,
and Precision Ag Technologies.
Today, I'm standing in the sorghum field
cause I want to talk about
some of our ongoing work
with nitrogen management in sorghum.
This is an important project
for us in Oklahoma state
because of one fault,
is that, in the Southern Great Plains,
nothing is guaranteed.
Often, we have things that come in
and really impact our crop at any given time.
While traditional mechanisms
from nitrogen management or pre-plant,
they're easy, they make sure everything's
in the system, honestly, in our area,
we don't know if we're gonna
to get a crop after we fertilize.
So in a way it's really putting all your eggs
in the basket of that one crop.
It's been my goal in many others
of the Oklahoma state at the university,
to develop management strategies and techniques,
or prove management strategies and techniques,
that can help producers make decisions,
after, they know they have a crop.
Making sure there's a stand, and it's
in an environment they wanna push
and try to thrive in.
So, today we're standing in this sorghum trial,
this is at Perkins,
we have this replicated at other locations
like Lake Carl Blackwell, and up in Alva.
This is a fun study for me,
It replicates some work we've done
in winter wheat, but we're really looking at
how long can this crop go, without nitrogen,
and then we supplement it, and it recover fully.
And we're really seeing some awesome results
in this first yeah,
some things that really make us rethink
So, first I want to show you the pre-plant plot.
How this trial works is, this plot right here,
this treatment, received nitrogen at planting.
In fact, it received 90 pounds of nitrogen.
You see, it's looking good.
This is our pre-plant,
it's getting ready to harvest.
But this was the only pot in this entire block,
that had any nitrogen at all,
prior to this was a cotton crop,
so it's a pretty well,
drained down, nutrient efficient soil.
Next to it here, this next plot,
this received nitrogen 28 days after planting.
So we're moving into a four week window,
after the application of nitrogen.
So we got 28 days after planting,
and then we move over here into this plot.
This plot right here is 35 days after planting,
where we see some good,
still good heads, good green.
Now, as I worked through these three plots,
I wanted to point out
some really interesting aspects
about what's happening, and what we're seeing.
First, let's look at the grain size, grain,
head size and the grains.
So in these, we see that our pre-plant plots
have good maturity,
good grain head,
the grains getting really close to harvest.
We're probably going to be cutting this,
and just the next couple of days.
Getting, or at least terminating
where at black layer,
we're going to be terminating.
But as we move into this plot,
this is the 28 day pot.
We noticed, we have
a few more green heads in there.
We had a little bit later,
of development in this plot.
And then we get into 35 days,
and there's a significant number of green heads.
One of the first observations
that the graduate student Mikayla Smith made
when she was working on this project,
is that, the delayed nitrogen plots, those plots
that really started delaying not showing
on 30 days or more,
We're starting to get into delay in maturity.
Is that good? Is it bad?
We don't know yet, but looking at the grain head size,
I don't think we're gonna have any yield loss,
at least for the thirst first 35 to 42 days,
It is interesting. Another aspect
that I think is extremely important about this
is the timing and our nitrogen use efficiency.
If we get down into it and we get
into the plots, we see in these plots,
on the NASA side, this pre-plant-plot,
It has a significant
amount of Croesus it's yellowing,
we have the crops going down and some of it
is due to maturity, a lot of it is due
to, it's just run out of nitrogen
that pre-plant went down,
and we had a fairly wet season, for spring.
So we start seeing deficiencies.
And as we move into the plot 28,
we don't see that same
Croesus going to depth,
but we do see a generalized croesus.
So we see this yellowing.
It's not just the greenest.
We're okay. We have good green,
but we're a little yellow.
But once we move into the 35 day,
we get into this,
and we start looking at some of these leaves,
now we're talking about a dark rich leaf,
that still has nitrogen.
And so we miss
that heavy rainfall period after planting,
and we're able to get the nitrogen on,
and really move through it,
and keep it through the plant,
and I expect that when we get this in,
and get all the trials, that 30 day window
is going to be a really good application window.
Now, how does this apply?
This allows us sometime to get in,
to look at the opportunity for the crop.
So we can really stand back and say, what?
I wanna make sure we have a stand,
get that stand up,
and you have a window,
a period where you can apply
and not lose anything. Now I want to move down to
some other plots.
There's some really interesting stuff
on down there.
This is a nice sandwich,
showing the zero pre-plant 28 through 84 days
after you can see nitrogen deficiencies,
and maturity differences across the crop.
Now this is the other end of the bar.
There's a pretty big trial.
So we moved down to look
some other plots.
This is the unfertilized check right here
that I'm in front of.
You see significant Croesus you see
these small heads,
you see pretty unripened berries moving through,
we have a plot here that, this is a 50 day plot.
So we have good green. Our heads are smaller.
We're starting to see that, we got good head count.
But we're really delayed so 50 days later,
we're getting still a lot of unripened berries.
We move through here, and there's still a lot of green,
and we're just pretty delighted.So what we seeing, is that
when we will start looking at that about 45 day and beyond,
we start having a full seven day,
to 10 day delay in maturity.
Now this can be used to the benefit.
If you are planting light and you want
to extend it past the heat period, or you're wanting
to move through, that might be an opportunity to extend,
or if you plant it early enough,
you have a little bit more time to grow
there's an opportunity there
as I look through the, the maturity,
or I looked through the plant health, these plants,
and we've seen this
in multiple crops.
These plants that have a delay
in nitrogen application,
tend to come out and being fairly healthy
after they'd been applied.
The recent research is suggesting
that plants that are under nitrogen stress early on
in the growing season may actually compete more
put more effort into rooting,
than into vegetative growth,
and we'll see that in wheat
where our late delayed nitrogen
is a much smaller crop, but it tends to weather
harsher weather patterns much better.
But Sorghum's an amazing crop.
It really is.
And I want to point this out.
This is a really cool plot down here.
We go right here,
and we have an area that's untreated,
we have our entry,
this is actually a border, but century check.
And this plot right here,
if you notice these heads are very similar
to an unfertilized head.
So, we have the heads here
of an unfertilized partner,
head size between these two
are quite similar,
so we have a definite loss in grain yield.
But look at the greenness of these plants,
just look at how green they go down
all the way down to the bottom.
This plot had Nitrogen-84 days after planting.
It looked just like that, 84 days before.
It looked just like that.
Just, right before we applied it and this crop,
this it's really amazing crop to me.
It's completely green back up.
It completely recovered at least vegetatively
from all the nitrogen stress.
And you can see that
in the nice green leaves.
Are we losing yield?
Am I going to tell you
to wait for 90 days?
Absolutely not that there's no sense in it,
but it just shows the amazing ability of this crop
to utilize nitrogen, utilize water,
any point. I would guess,
and I'm starting to sit on these
that we're going to have tillers.
So this is an opportunity.
If things go bad and you just hold off,
we're going to start seeing more tillers coming on.
We could have a second crop on this. You never know.
Sorghum always seems to battle.
Your time listening to this today.
I hope it was worth her while we'll be doing more
of these walkthrough trials
and posting them online.
I want to talk about the wheat data
that was mentioned in the first part
of the sorghum video,
and is a delayed nitrogen wheat project,
a little background,
and why it's important for us is that
what is documented well,
that nitrogen uptake is still occurring
even after flowering.
So Amanda, Dr. Silva now who works
with OSU hall,
she goes to Kansas documented
that at flowering beyond
there's still 20% of the total nitrogen,
the crop can take.
Along with the fact that Oklahoma state's been promoting
the enrich strip since the late nineties.
And the concept of the interest strip
is you have a higher rate of nitrogen
in the field.
And whenever that shows up
the rest of the fields deficient,
and we make a recommendation
and we apply that makes the assumption
we can recover from stress agronomically.
I always told folks,what?
You got to get it on within 30 days
of that stress being shown,
or you might lose yield.
That was just an estimate,
a guestimate, not really knowing.
So this project really attacked that concept.
Started it in the fall of 2016,
one of the test,
the inner strip delay mean.
How long could we be deficient
and recover used ammonium nitrate,
as an action source.
So we didn't have a interacting effect
of urea hydrolysis or volatilization
trying to maintain that.
And it goes in
that we have a pre-plant,
plot, and a zero in plot,
everything else received, no nitrogen. Well,
the pre-plant received notch and everything else
that planted did not.
Whenever that pre-plant showed up,
we started fertilizing.
So this pot right here,
zero David basically
stands for zero days after visual difference.
So whenever we saw difference,
we started applying there
and then every seven growing degree days greater than zero,
meaning a day of growth.
We started applying and we applied up to 63.
And so that in many cases,
when he was anywhere between 80
to a hundred calendar days
after visual deficiencies.
it shows nicely how it looks.
We have the pre-plant, the check,
and then those, you see the closer you get
to the last application,
it gets greener and greener.
This shows the timings
of the first two, where we had differentiation
or nutrient deficiencies from November
to February. Last application from February to May.
For Oklahoma, we're in Hollow stem,
somewhere around the first week of March.
So this green that's our March dates.
That's typically when we start hitting hollow stem
and we would typically want
to be done applying nitrogen by that point.
Start looking at first year of data
and this top graph is the yield of the
in season, versus the yield
of the pre-point and the bottom is the protein of the
in season versus the pre-plant.
If the box is yellow,
that means yield was statistically the same
as a pre-plant. Right.
If the box is
that greenish blue,
it was significantly better.
The pink color is significantly worse.
So on most cases on the yield,
you see yield was equal to or better
than the pre-point,
when we waited in season
and the protein by far,
the further you waited,
the better the protein gotten a higher win.
So, we had true good data that says, what?
We can maintain yields,
and improve protein at the minimum
and if not improving protein and yields.
Looking at it versus the zero David meaning that,
that first efficiency
is when we applied nitrogen versus the others.
We very seldom loss.
We waited many days after.
So we're at 56 days
of growth after deficiency,
without showing any negative losses,
except for this one over here,
the pre-plant. So in season is the same almost two
or 60 days of growth after deficiency.
In many cases,
yield is even better, showing that,
but first two years, like,
know what this is.
We've had word years.
I'm not going to trust this,
when we gotta do it again,
moved on to 18,
19 same data to different locations.
Hollow stem is somewhere around
early March, between the 8th and the 15th
was hollow stem about two
to three weeks after hollow stem,
the end of March,
we're maximizing yield and maximizing protein
in most cases,
looking to be overall pretty good.
And then this last year, we go,
our last year of this project,
we've got pre-Point in season,
deficiencies seen around early February.
We're applying into late March maximizing yield,
maximizing protein in late March,
which is about a month after hollow stem,
still seeing good yields on protein.
I'm not telling people to wait till that late,
but I'm telling them don't get
in a rush like, Oh,
I got to apply, I got to apply,
and the weather is not cooperating,
for your nitrogen applications.
Do it so that when you apply that nitrogen,
it's a best case for getting full utilization
of that nitrogen.
And honestly, the longer you wait
and the closer you get the hollow stem,
the better your final product is going to be,
and you haven't lost any yield.
So again, we've got
a lot of other projects in this.
We're putting this
on the web all the time.
This blog has been updated and will be updated
with the new data very soon,
check out my blog.
You can find me on Twitter,
you can find me on Facebook
and you can find me on YouTube.
Thank you very much,
and I greatly appreciate your time and your attention today.
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