Nitrogen Timing in Sorghum and Wheat

University of Nebraska – Lincoln Author

08/31/2020 Added

13 Plays

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Dr. Brian Arnall looks at research results of nitrogen timing both sorghum and wheat.
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[00:00:16.580]Hello. My name is Brian
[00:00:18.250]and now I'm with Oklahoma state university.
[00:00:20.670]My title is a precision nutrient
[00:00:22.140]management extension specialist.
[00:00:25.392]My job is to help producers,
[00:00:26.225]and the people of the state,
[00:00:27.170]with their nutrient management decisions,
[00:00:29.310]and Precision Ag Technologies.
[00:00:31.470]Today, I'm standing in the sorghum field
[00:00:32.980]cause I want to talk about
[00:00:33.813]some of our ongoing work
[00:00:35.110]with nitrogen management in sorghum.
[00:00:37.490]This is an important project
[00:00:39.070]for us in Oklahoma state
[00:00:40.730]because of one fault,
[00:00:42.090]is that, in the Southern Great Plains,
[00:00:45.140]nothing is guaranteed.
[00:00:46.970]Often, we have things that come in
[00:00:48.860]and really impact our crop at any given time.
[00:00:52.920]While traditional mechanisms
[00:00:54.730]from nitrogen management or pre-plant,
[00:00:56.830]they're easy, they make sure everything's
[00:00:59.020]in the system, honestly, in our area,
[00:01:02.560]we don't know if we're gonna
[00:01:03.550]to get a crop after we fertilize.
[00:01:05.630]So in a way it's really putting all your eggs
[00:01:07.750]in the basket of that one crop.
[00:01:10.210]It's been my goal in many others
[00:01:11.740]of the Oklahoma state at the university,
[00:01:13.800]to develop management strategies and techniques,
[00:01:17.590]or prove management strategies and techniques,
[00:01:20.460]that can help producers make decisions,
[00:01:22.450]after, they know they have a crop.
[00:01:24.830]Making sure there's a stand, and it's
[00:01:26.870]in an environment they wanna push
[00:01:28.760]and try to thrive in.
[00:01:30.410]So, today we're standing in this sorghum trial,
[00:01:33.090]this is at Perkins,
[00:01:34.390]we have this replicated at other locations
[00:01:36.470]like Lake Carl Blackwell, and up in Alva.
[00:01:39.230]This is a fun study for me,
[00:01:41.080]It replicates some work we've done
[00:01:42.600]in winter wheat, but we're really looking at
[00:01:44.750]how long can this crop go, without nitrogen,
[00:01:48.870]and then we supplement it, and it recover fully.
[00:01:51.630]And we're really seeing some awesome results
[00:01:53.940]in this first yeah,
[00:01:55.070]some things that really make us rethink
[00:01:56.930]what's happening.
[00:01:58.010]So, first I want to show you the pre-plant plot.
[00:02:01.360]How this trial works is, this plot right here,
[00:02:04.330]this treatment, received nitrogen at planting.
[00:02:08.230]In fact, it received 90 pounds of nitrogen.
[00:02:11.630]You see, it's looking good.
[00:02:13.280]This is our pre-plant,
[00:02:14.460]it's getting ready to harvest.
[00:02:16.280]But this was the only pot in this entire block,
[00:02:19.090]that had any nitrogen at all,
[00:02:20.330]prior to this was a cotton crop,
[00:02:21.870]so it's a pretty well,
[00:02:23.160]drained down, nutrient efficient soil.
[00:02:25.519]Next to it here, this next plot,
[00:02:28.110]this received nitrogen 28 days after planting.
[00:02:32.840]So we're moving into a four week window,
[00:02:35.240]after the application of nitrogen.
[00:02:37.040]So we got 28 days after planting,
[00:02:39.095]and then we move over here into this plot.
[00:02:42.000]This plot right here is 35 days after planting,
[00:02:45.870]where we see some good,
[00:02:47.440]still good heads, good green.
[00:02:49.530]Now, as I worked through these three plots,
[00:02:51.130]I wanted to point out
[00:02:52.700]some really interesting aspects
[00:02:54.580]about what's happening, and what we're seeing.
[00:02:57.010]First, let's look at the grain size, grain,
[00:02:58.890]head size and the grains.
[00:03:00.950]So in these, we see that our pre-plant plots
[00:03:04.550]have good maturity,
[00:03:05.702]good grain head,
[00:03:07.940]the grains getting really close to harvest.
[00:03:10.380]We're probably going to be cutting this,
[00:03:11.810]and just the next couple of days.
[00:03:13.683]Getting, or at least terminating
[00:03:15.340]where at black layer,
[00:03:16.173]we're going to be terminating.
[00:03:17.550]But as we move into this plot,
[00:03:19.110]this is the 28 day pot.
[00:03:20.650]We noticed, we have
[00:03:21.500]a few more green heads in there.
[00:03:22.957]We had a little bit later,
[00:03:25.010]of development in this plot.
[00:03:26.990]And then we get into 35 days,
[00:03:29.220]and there's a significant number of green heads.
[00:03:32.570]One of the first observations
[00:03:33.960]that the graduate student Mikayla Smith made
[00:03:35.406]when she was working on this project,
[00:03:37.610]is that, the delayed nitrogen plots, those plots
[00:03:40.110]that really started delaying not showing
[00:03:42.000]on 30 days or more,
[00:03:43.640]We're starting to get into delay in maturity.
[00:03:46.450]Is that good? Is it bad?
[00:03:47.750]We don't know yet, but looking at the grain head size,
[00:03:50.590]I don't think we're gonna have any yield loss,
[00:03:52.520]at least for the thirst first 35 to 42 days,
[00:03:55.580]after planning.
[00:03:56.780]It is interesting. Another aspect
[00:03:59.200]that I think is extremely important about this
[00:04:01.320]is the timing and our nitrogen use efficiency.
[00:04:05.270]If we get down into it and we get
[00:04:06.970]into the plots, we see in these plots,
[00:04:09.850]on the NASA side, this pre-plant-plot,
[00:04:12.610]It has a significant
[00:04:13.750]amount of Croesus it's yellowing,
[00:04:16.750]we have the crops going down and some of it
[00:04:19.290]is due to maturity, a lot of it is due
[00:04:21.300]to, it's just run out of nitrogen
[00:04:23.440]that pre-plant went down,
[00:04:25.090]and we had a fairly wet season, for spring.
[00:04:27.910]So we start seeing deficiencies.
[00:04:29.960]And as we move into the plot 28,
[00:04:33.810]we don't see that same
[00:04:35.270]Croesus going to depth,
[00:04:36.540]but we do see a generalized croesus.
[00:04:38.870]So we see this yellowing.
[00:04:40.510]It's not just the greenest.
[00:04:42.170]We're okay. We have good green,
[00:04:44.130]but we're a little yellow.
[00:04:46.180]But once we move into the 35 day,
[00:04:49.010]we get into this,
[00:04:50.610]and we start looking at some of these leaves,
[00:04:53.060]now we're talking about a dark rich leaf,
[00:04:55.890]that still has nitrogen.
[00:04:57.440]And so we miss
[00:04:58.640]that heavy rainfall period after planting,
[00:05:01.480]and we're able to get the nitrogen on,
[00:05:03.500]and really move through it,
[00:05:05.420]and keep it through the plant,
[00:05:06.670]and I expect that when we get this in,
[00:05:09.410]and get all the trials, that 30 day window
[00:05:11.796]is going to be a really good application window.
[00:05:14.430]Now, how does this apply?
[00:05:15.940]This allows us sometime to get in,
[00:05:18.400]to look at the opportunity for the crop.
[00:05:20.840]So we can really stand back and say, what?
[00:05:23.360]I wanna make sure we have a stand,
[00:05:25.010]get that stand up,
[00:05:25.940]and you have a window,
[00:05:27.130]a period where you can apply
[00:05:28.870]and not lose anything. Now I want to move down to
[00:05:31.730]some other plots.
[00:05:32.640]There's some really interesting stuff
[00:05:33.990]on down there.
[00:05:37.390]This is a nice sandwich,
[00:05:38.290]showing the zero pre-plant 28 through 84 days
[00:05:42.400]after you can see nitrogen deficiencies,
[00:05:44.660]and maturity differences across the crop.
[00:05:49.090]Now this is the other end of the bar.
[00:05:49.923]There's a pretty big trial.
[00:05:51.380]So we moved down to look
[00:05:52.650]some other plots.
[00:05:53.640]This is the unfertilized check right here
[00:05:55.610]that I'm in front of.
[00:05:56.630]You see significant Croesus you see
[00:05:58.930]these small heads,
[00:06:00.330]you see pretty unripened berries moving through,
[00:06:03.400]we have a plot here that, this is a 50 day plot.
[00:06:06.570]So we have good green. Our heads are smaller.
[00:06:08.880]We're starting to see that, we got good head count.
[00:06:12.040]But we're really delayed so 50 days later,
[00:06:14.010]we're getting still a lot of unripened berries.
[00:06:16.250]We move through here, and there's still a lot of green,
[00:06:21.735]and we're just pretty delighted.So what we seeing, is that
[00:06:26.310]when we will start looking at that about 45 day and beyond,
[00:06:29.920]we start having a full seven day,
[00:06:32.080]to 10 day delay in maturity.
[00:06:34.870]Now this can be used to the benefit.
[00:06:37.470]If you are planting light and you want
[00:06:39.720]to extend it past the heat period, or you're wanting
[00:06:42.490]to move through, that might be an opportunity to extend,
[00:06:45.340]or if you plant it early enough,
[00:06:47.040]you have a little bit more time to grow
[00:06:49.060]there's an opportunity there
[00:06:50.690]as I look through the, the maturity,
[00:06:52.560]or I looked through the plant health, these plants,
[00:06:55.780]and we've seen this
[00:06:56.613]in multiple crops.
[00:06:57.640]These plants that have a delay
[00:06:59.400]in nitrogen application,
[00:07:01.010]tend to come out and being fairly healthy
[00:07:02.870]after they'd been applied.
[00:07:04.540]The recent research is suggesting
[00:07:06.900]that plants that are under nitrogen stress early on
[00:07:09.870]in the growing season may actually compete more
[00:07:12.380]put more effort into rooting,
[00:07:14.670]than into vegetative growth,
[00:07:16.130]and we'll see that in wheat
[00:07:17.210]where our late delayed nitrogen
[00:07:18.720]is a much smaller crop, but it tends to weather
[00:07:21.270]harsher weather patterns much better.
[00:07:24.240]But Sorghum's an amazing crop.
[00:07:25.570]It really is.
[00:07:26.406]And I want to point this out.
[00:07:27.239]This is a really cool plot down here.
[00:07:29.640]We go right here,
[00:07:31.290]and we have an area that's untreated,
[00:07:33.410]we have our entry,
[00:07:34.243]this is actually a border, but century check.
[00:07:36.300]And this plot right here,
[00:07:37.470]if you notice these heads are very similar
[00:07:40.700]to an unfertilized head.
[00:07:46.916]So, we have the heads here
[00:07:48.220]of an unfertilized partner,
[00:07:49.410]head size between these two
[00:07:51.410]are quite similar,
[00:07:52.260]so we have a definite loss in grain yield.
[00:07:55.800]But look at the greenness of these plants,
[00:07:57.880]just look at how green they go down
[00:08:00.330]all the way down to the bottom.
[00:08:02.300]This plot had Nitrogen-84 days after planting.
[00:08:08.350]It looked just like that, 84 days before.
[00:08:14.170]It looked just like that.
[00:08:16.380]Just, right before we applied it and this crop,
[00:08:19.320]this it's really amazing crop to me.
[00:08:21.810]It's completely green back up.
[00:08:23.660]It completely recovered at least vegetatively
[00:08:26.890]from all the nitrogen stress.
[00:08:28.906]And you can see that
[00:08:29.739]in the nice green leaves.
[00:08:31.020]Are we losing yield?
[00:08:32.150]Absolutely.
[00:08:32.983]Am I going to tell you
[00:08:33.816]to wait for 90 days?
[00:08:34.990]Absolutely not that there's no sense in it,
[00:08:38.100]but it just shows the amazing ability of this crop
[00:08:42.570]to utilize nitrogen, utilize water,
[00:08:45.530]any point. I would guess,
[00:08:47.270]and I'm starting to sit on these
[00:08:48.780]that we're going to have tillers.
[00:08:50.340]So this is an opportunity.
[00:08:51.690]If things go bad and you just hold off,
[00:08:54.210]we're going to start seeing more tillers coming on.
[00:08:56.240]We could have a second crop on this. You never know.
[00:08:58.710]Sorghum always seems to battle.
[00:09:01.590]Your time listening to this today.
[00:09:03.450]I hope it was worth her while we'll be doing more
[00:09:06.210]of these walkthrough trials
[00:09:07.830]and posting them online.
[00:09:09.250]Okay.
[00:09:10.480]I want to talk about the wheat data
[00:09:11.405]that was mentioned in the first part
[00:09:13.060]of the sorghum video,
[00:09:14.750]and is a delayed nitrogen wheat project,
[00:09:17.630]a little background,
[00:09:18.920]and why it's important for us is that
[00:09:21.702]what is documented well,
[00:09:22.535]that nitrogen uptake is still occurring
[00:09:25.120]even after flowering.
[00:09:26.110]So Amanda, Dr. Silva now who works
[00:09:29.100]with OSU hall,
[00:09:29.933]she goes to Kansas documented
[00:09:31.600]that at flowering beyond
[00:09:33.050]there's still 20% of the total nitrogen,
[00:09:34.710]the crop can take.
[00:09:36.400]Along with the fact that Oklahoma state's been promoting
[00:09:38.790]the enrich strip since the late nineties.
[00:09:41.800]And the concept of the interest strip
[00:09:43.120]is you have a higher rate of nitrogen
[00:09:45.170]in the field.
[00:09:46.080]And whenever that shows up
[00:09:47.610]the rest of the fields deficient,
[00:09:48.830]and we make a recommendation
[00:09:50.500]and we apply that makes the assumption
[00:09:52.560]we can recover from stress agronomically.
[00:09:55.330]I always told folks,what?
[00:09:57.290]You got to get it on within 30 days
[00:09:59.210]of that stress being shown,
[00:10:00.940]or you might lose yield.
[00:10:02.260]That was just an estimate,
[00:10:03.690]a guestimate, not really knowing.
[00:10:06.050]So this project really attacked that concept.
[00:10:09.880]Started it in the fall of 2016,
[00:10:12.470]one of the test,
[00:10:13.303]the inner strip delay mean.
[00:10:14.890]How long could we be deficient
[00:10:16.510]and recover used ammonium nitrate,
[00:10:19.010]as an action source.
[00:10:19.843]So we didn't have a interacting effect
[00:10:21.560]of urea hydrolysis or volatilization
[00:10:24.210]trying to maintain that.
[00:10:25.710]And it goes in
[00:10:26.543]that we have a pre-plant,
[00:10:27.870]plot, and a zero in plot,
[00:10:29.920]everything else received, no nitrogen. Well,
[00:10:32.410]the pre-plant received notch and everything else
[00:10:34.000]that planted did not.
[00:10:35.090]Whenever that pre-plant showed up,
[00:10:36.640]we started fertilizing.
[00:10:37.690]So this pot right here,
[00:10:38.760]zero David basically
[00:10:40.720]stands for zero days after visual difference.
[00:10:42.740]So whenever we saw difference,
[00:10:43.960]we started applying there
[00:10:45.390]and then every seven growing degree days greater than zero,
[00:10:48.720]meaning a day of growth.
[00:10:49.970]We started applying and we applied up to 63.
[00:10:53.180]And so that in many cases,
[00:10:55.130]when he was anywhere between 80
[00:10:56.720]to a hundred calendar days
[00:10:58.530]after visual deficiencies.
[00:11:02.150]Another image,
[00:11:03.980]it shows nicely how it looks.
[00:11:05.470]We have the pre-plant, the check,
[00:11:08.120]and then those, you see the closer you get
[00:11:10.600]to the last application,
[00:11:11.433]it gets greener and greener.
[00:11:14.360]This shows the timings
[00:11:15.660]of the first two, where we had differentiation
[00:11:18.240]or nutrient deficiencies from November
[00:11:21.120]to February. Last application from February to May.
[00:11:24.650]For Oklahoma, we're in Hollow stem,
[00:11:27.260]somewhere around the first week of March.
[00:11:29.300]So this green that's our March dates.
[00:11:31.540]That's typically when we start hitting hollow stem
[00:11:34.190]and we would typically want
[00:11:35.560]to be done applying nitrogen by that point.
[00:11:38.820]Start looking at first year of data
[00:11:40.270]and this top graph is the yield of the
[00:11:42.160]in season, versus the yield
[00:11:43.990]of the pre-point and the bottom is the protein of the
[00:11:45.637]in season versus the pre-plant.
[00:11:47.870]If the box is yellow,
[00:11:49.280]that means yield was statistically the same
[00:11:52.070]as a pre-plant. Right.
[00:11:53.180]If the box is
[00:11:54.013]that greenish blue,
[00:11:54.846]it was significantly better.
[00:11:56.800]The pink color is significantly worse.
[00:11:58.610]So on most cases on the yield,
[00:12:00.570]you see yield was equal to or better
[00:12:02.700]than the pre-point,
[00:12:03.830]when we waited in season
[00:12:05.960]and the protein by far,
[00:12:07.680]the further you waited,
[00:12:09.260]the better the protein gotten a higher win.
[00:12:11.750]So, we had true good data that says, what?
[00:12:14.120]We can maintain yields,
[00:12:15.840]and improve protein at the minimum
[00:12:17.840]and if not improving protein and yields.
[00:12:21.210]Looking at it versus the zero David meaning that,
[00:12:24.960]that first efficiency
[00:12:26.020]is when we applied nitrogen versus the others.
[00:12:28.860]We very seldom loss.
[00:12:30.410]We waited many days after.
[00:12:32.960]So we're at 56 days
[00:12:35.880]of growth after deficiency,
[00:12:37.630]without showing any negative losses,
[00:12:39.540]except for this one over here,
[00:12:41.400]the pre-plant. So in season is the same almost two
[00:12:45.570]or 60 days of growth after deficiency.
[00:12:48.510]In many cases,
[00:12:49.510]yield is even better, showing that,
[00:12:52.260]but first two years, like,
[00:12:53.670]know what this is.
[00:12:54.550]We've had word years.
[00:12:56.210]I'm not going to trust this,
[00:12:57.240]when we gotta do it again,
[00:12:58.620]moved on to 18,
[00:12:59.453]19 same data to different locations.
[00:13:02.770]Hollow stem is somewhere around
[00:13:04.120]early March, between the 8th and the 15th
[00:13:06.817]was hollow stem about two
[00:13:09.730]to three weeks after hollow stem,
[00:13:10.617]the end of March,
[00:13:11.940]we're maximizing yield and maximizing protein
[00:13:14.320]in most cases,
[00:13:15.740]looking to be overall pretty good.
[00:13:18.600]And then this last year, we go,
[00:13:20.010]our last year of this project,
[00:13:22.040]we've got pre-Point in season,
[00:13:25.600]deficiencies seen around early February.
[00:13:28.520]We're applying into late March maximizing yield,
[00:13:31.050]maximizing protein in late March,
[00:13:32.650]which is about a month after hollow stem,
[00:13:34.520]still seeing good yields on protein.
[00:13:37.070]I'm not telling people to wait till that late,
[00:13:40.230]but I'm telling them don't get
[00:13:41.940]in a rush like, Oh,
[00:13:43.340]I got to apply, I got to apply,
[00:13:45.100]and the weather is not cooperating,
[00:13:47.660]for your nitrogen applications.
[00:13:50.210]Do it so that when you apply that nitrogen,
[00:13:52.210]it's a best case for getting full utilization
[00:13:54.500]of that nitrogen.
[00:13:55.430]And honestly, the longer you wait
[00:13:57.060]and the closer you get the hollow stem,
[00:13:58.650]the better your final product is going to be,
[00:14:00.720]and you haven't lost any yield.
[00:14:02.680]So again, we've got
[00:14:03.800]a lot of other projects in this.
[00:14:06.060]We're putting this
[00:14:07.010]on the web all the time.
[00:14:08.330]This blog has been updated and will be updated
[00:14:10.130]with the new data very soon,
[00:14:12.250]check out my blog.
[00:14:13.090]OSUNPK.com
[00:14:14.350]You can find me on Twitter,
[00:14:15.330]you can find me on Facebook
[00:14:16.270]and you can find me on YouTube.
[00:14:18.170]Thank you very much,
[00:14:19.050]and I greatly appreciate your time and your attention today.

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Nitrogen Timing in Sorghum and Wheat

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