Grains Research Updates 2015 | Goondiwindi | Sorghum agronomy: maximise yield potential – L. Serafin

Grains Research Updates 2015 | Goondiwindi | Sorghum agronomy: maximise yield potential – L. Serafin


Today I’ve been asked to talk about basically
all of our sorghum research in 15 minutes. So it could be a quick 15 minutes, but I suppose
Guy McMullen and myself, who are based out of Tamworth in New South Wales DPI, thought
that we would probably be best covering off just on two of our sorghum research projects
and probably giving you bit of insight into those rather than trying to cover absolutely
everything. So the two aspects that we’ve chosen to talk
about today is firstly, our project based in the medium to high yielding zone, so we’re
talking about Liverpool Plains, and so we’ll be talking about a site based at Breeza last
season. So the first year of trials there under the high yielding cereal agronomy project,
and that site was one of two last year that we had on the Plains. We’re just going to
talk about Breeza today though, because it had both a dryland and an irrigated trial
at the same site. So there’s some good comparison there from those two different trials. And
then secondly, I’ll be talking about some more comprehensive research that we’ve had
underway for the last five years in this area here west of the Newell Highway, and that’s
under the sorghum in the western zone project. And I’m sure many of you have heard components
of that over the last couple of years, so it’s really a bit of an update as to what’s
happening now. So if we start it off with the medium to high
yielding zone. So really we’re talking about a research project there that’s actually
targeted at an area where sorghum is an integral part of the rotation. So it’s an area where
growers are comfortable growing sorghum. They know it’s profitable. It’s a major part
of their rotation, and the yields that they get are good. The focus we’re putting on
it though at the moment, is how much better could we make their yields? So we now currently
at Gunnedah the long-term average yields are just under four tonne to the hectare, but
we also know that from dealing with growers commercially they’ve been able to achieve
up to 12 tonnes to the hectare in dryland situations. So you can see that there’s
a pretty large gap there between what the average yields are and what potentially we
know that growers are able to achieve, so the aim of this project has been to actually
start to break down and partition what we’re doing with our crop management, and what the
different contributing factors are to actually achieving those top-end yields. So as part of that, we’ve designed a series
of experiments. The experiment at Breeza last year was made up of a combination of 24 different
treatments. It was a partially factorial trial, and that’s really just because if we had
the whole combination of all of the treatment options, it would really be prohibitive in
terms of size. So last year at Breeza we had both the dryland and the irrigated trial,
and we included a range of different factors. So we included a time of sowing component.
So we started with an early or an ideal timing at the end of October, and then we included
a late time of sowing, so a time of sowing 2, which was actually in the first week of
December. Then we’ve overlaid on top of that a hybrid component. So we selected three
hybrids: we chose Buster because it’s a commercial hybrid that people are very comfortable
with; and then we selected two new release hybrids or recent release hybrids. So in this
case we actually used MR Scorpio from Pacific Seeds, and we used 85G33 from Pioneer. We
then included a range of different plant populations, so 50, 75 and 100 thousand plants to the hectare.
And then on top of that, just to make it a little bit more complicated, we included a
row configuration aspect. So at our Breeza Research Station last year we were on 1.8
metre raised beds, so we included a 90 centimetre solid row spacing, and then we also included
a twin row spacing component. So with the twin row spacing component, what we actually
did was planted an additional two rows inside the 90 centimetres, so there was 7.5 centimetres
or three inches between the two rows, so quite close together. We also tried to include some
of the nutritional aspects. Obviously there’s a wider range than just nitrogen and phosphorous,
but for the largest yield benefits – I suppose looking for the biggest return on your investment
– we included three rates of nitrogen: so zero, 100, and 200 kilos of N to the hectare.
And we included three rates of phosphorous: so zero, 10 and 20. And both of those were
applied at sowing, as urea or as triple superphosphate, so just as single nutrients. The irrigated trial had two irrigations, and
the timing of those actually ended being on the same dates for time of sowing 1 and 2,
and that was really just because we had rainfall earlier on in time of sowing 1. So it didn’t
need an irrigation prior to that point. The site itself actually was quite low in nitrogen,
so as you can see, about 46 kilos of nitrogen down to 1.2 metres, and a reasonably good
profile of about 187 mils of plant available water for sorghum. Let us look at the results. So we started
first with looking at the effect of time of sowing, so what was the difference between
that ideal sowing at the end of October and then delaying it about six weeks until early
December last year? So these graphs have the plant population component included as well,
and so you can see the significance letters there. If we look first at the dryland graph,
where basically our average yields are just over three tonne to the hectare, about 3.4
tonnes to the hectare. What we can see is that time of sowing 1 yielded more than time
of sowing 2, but only at the higher populations; so only at the 75 and 100 thousand plants
to the hectare. There was no difference at the 50,000 plants to the hectare between time
of sowing 1 or time of sowing 2. So they yielded the same. In contrast, at the irrigated site,
where you can see our yields have lifted to our averages being closer to the 6 tonne to
the hectare mark, there was no difference in the time of sowing last year. So we then tried to break apart our row spacing,
and what are the contributions to yield there from varying our row spacing? What we saw
with the dryland trial was that the 90 centimetre solid rows outyielded the twin rows at both
times of sowing. So it was a pretty clear response there. It was a little bit more complicated
with the irrigated site. So with the irrigated trials, both the 90 cm row spacings for the
time of sowing 1 and 2 – so both times of sowing – yielded the same, and the twin row
spacing for the first time of sowing also yielded the same, but it was the twin row
spacing on the second time of sowing that actually yielded significantly less. So a
slight reduction there. But overall, as you can see under the irrigation, not a major
impact on yields from the different row configurations. So we moved across to hybrids: so obviously
there’s a lot of focus from growers and advisors on picking the right hybrid each
season and the hybrid that’s going to yield the best. As I’ve outlined, we chose MR Buster
because it’s a commercial standard, and then we chose two recent release hybrids because
we’re looking to see if we could actually show the genetic gain from the newer hybrids
coming out onto the market. So with G33 and Scorpio and Buster, we put them all under
the same treatment conditions. So we gave one set of treatments where they were all
planted at 50,000 plants to the hectare; a 90cm row spacing, 100 kilos of nitrogen, and
10 units of phosphorous and then we compared their yields. What we saw last year, and you can see from
how close these bars are together probably even before I put up this next bit, is that
there was no significant difference between any of the hybrids last year under the dryland
or the irrigated trial. So if you’re looking at the partitioning of yields so far, we can
see that the hybrid selections hasn’t actually added a lot in last season’s trials, but
what has a major impact last season has been our crop nutrition. So we got the largest
response to nitrogen, in terms of varying our treatments. So as I mentioned, we started with quite a
small amount of nitrogen in the profile; only enough to actually yield about 1.5 tonnes
per hectare, and that’s excluding any mineralisation that occurred in season last year. It was
a quite a dry season, as many of you will probably recall. And then over that low starting
N, we added the three treatments. The we added a zero, 100 kilos and 200 kilos. So we added
enough nitrogen, in essence, to target about a 7.5 tonne to the hectare yield. Pretty clearly
you can see that in the dryland trial, in your top left there, that our best response
from was from applying the 200 kilos of nitrogen to the hectare. So in essence, we’ve taken
it from between two and three tonnes to the hectare up to nearly double that from the
addition of 200 kilos. Similar story with the irrigated trial, only
obviously our yields were higher, but still a fairly large response to that 200 kilos
of nitrogen. The question that obviously sticks in my mind and hopefully is in your mind from
looking at this line, is what would have happened if we had applied additional nitrogen? So
we didn’t top out the trial there, so was there potential to actually lift those yields
further by applying a higher rate? The other question is obviously about the
economics. So just to horrify the economists in the room, I did a quick back of the envelope
calculation. Last week at Werris Creek sorghum was $250 a tonne. Urea in tonne worth was
$645 a tonne, so it actually worked out to be an $875 dollar profit from applying that
200 kilos of nitrogen, compared to our nil treatment. With phosphorous, the story was a little similar
but not quite as clear. So what we saw with phosphorous was that when we applied just
10 units of phosphorous but no nitrogen, we didn’t really get a very significant response.
Certainly, under the dryland trial we didn’t get a significant response at all. In the
irrigated trial it was a little better. But the best responses were in combination. So
when we actually added nitrogen and phosphorous together, that was where we had significantly
higher yields. Again, as I said in the nitrogen, the beauty of hindsight is that you look at
these treatments afterwards and think, wouldn’t it have been nice if I’d had just 20 kilos
of phosphorous by itself as a treatment alone, but you can’t have everything, Guy keeps
telling me. From that medium to high yielding zone, what
are the take home messages? First up, one year’s data, so it’s a preliminary trial set,
so please keep that in mind. Obviously we’ve got trials underway this season so there’ll
be additional data to go with it. At this stage the early planting time has been higher
yielding, and we’ve seen that significant response to population as well. So 75 and
100 thousand plants to the hectare have been higher yielding than our 50,000, which is
what we’re currently focusing on. There was no significant difference between
the hybrids last year, but we did have a very strong response to some of the nutritional
components. So if you are going to be making an investment at the moment, nutrition appears
to be one of the best responses that we could look at. And finally if we looked at row configuration
last year, there wasn’t a major response in terms of our yields. There were differences,
but they were quiet minimal. If we skip then to the other project, so now
looking at sorghum in the western zone project here, which has been running since 2010. So
this is a bit of an overview of what has happened over the last five years. As a bit of a refresher
or for those who haven’t seen any of this work before, this project is focused on that
low to medium yielding environment. So all the trials are west of the Newell, and over
the last five years we’ve had nine successful drylands trials. We have planted a couple
of others which have either succumbed to flood, which is probably a little hard to believe
at the moment, or drought. So last year we lost a couple of trials through extended drought. Of the nine successful trials, we’ve overlaid
a series of different components. So we’ve called these the GEM trials. So we’ve combined
the genotype differences. So there was three hybrids that were selected for their characteristics;
not for the specific hybrid. So we used 2436, which is an experimental line and it was selected
because it’s low tillering but has high stay-green. We used MR 43, because it’s
a moderate tillering and moderate stay-green, so it’s that kind of middle of the road.
And then we’ve used MR Bazley which is high tillering but low stay-green, so you can see
it’s the contrast to 2436. As I’ve mentioned we ran the western environment and then we’ve
overlaid a series of management factors. So we’ve run both early and late plant trials,
depending on the season and the site availability, and then we’ve included four different plant
populations, 15, 30, 50 and 70 thousand plants to the hectare, and four different row configurations.
So a solid one metre, which is obviously not very common in this environment; a single
skip or a 1.5 metre solid plant which we refer to as a super wide; and then a double skip. So if we look at the results here: a couple
of quick slides to give you overview of what has happened. Firstly, the plant population.
So in the first couple of years, we ran 30, 50 and 70 thousand plants to the hectare.
In those first years, which have been obviously very high yielding compared to what the average
is in many of these environments – so where some of the plots were going 6, 6.5 tonne
to the hectare – what we saw was that the 50 and 70 thousand plants to the hectare were
always higher yielding, and generally there was no difference between those two high populations.
The 30,000 plants to the hectare was never able to compete in that situation. So what
we then revised was, why would a grower want to plant 70,000 plants to the hectare because
it was going to be an additional seed cost, if they actually weren’t going to get any
additional return. So we removed the 70,000 plants to the hectare and replaced it with
a lower plant population. So from 2012/13 season you can see here we’ve
started to include this mauve bar, which was 15,000 plants to the hectare, which is a fairly
common question from growers, particularly in the Walgett and Rowena area, is how low
can we really go? So we thought we’ll try and capture some data from that very low side
of the spectrum as well. What we’ve seen over the last couple of years, with the exemption
of the site at Tulloona last year, which you’ll see keeps reappearing in the coming slides
here as a very low yielding site – just over a tonne to the hectare, and very unresponsive
to pretty much any change in treatments. But with the exemption of Tulloona, what we’ve
seen so far has been that 30 and 50 thousand have been more comparable over the last couple
of seasons and the 15,000 is really the treatment that hasn’t been able to compete. So to
date, we’re still recommending to growers that they’d be best targeting their populations
around the 50,000 plants to the hectare, and if they were going to go lower, then it would
be down potentially to 30,000, but we’re still more confident in the 40 to 50 thousand
plants to the hectare in that environment. If we looked at row configuration, it’s
been a fairly clear story over most of these sites as well, with the exception, as I said,
of Tulloona – the thorn in the side here. I just had to include it though. What we’ve seen over the last five years
has been that our solid plant configuration has consistently outyielded any of the other
configurations. Keeping in mind that that solid plant is a very high risk option for
growers in that environment, because typically they’re not expecting to be yielding five
tonne to the hectare each season. The solid plant has always outyielded the single skip
and the 1.5 metre solid, and they’ve been comparable as treatments. And they’ve all
outyielded the double skip. If we actually moved on to comparing the configurations
as effective row spacings though, we start to see probably an easier trend. So what we’ve
done here is if you look at solid plant and your one metre effective row spacing: if we
considered that to be our 100% yield potential, and then our 1.5 metre row spacing is the
single skip or the super wide treatments; and the two metre is our double skip treatment,
what we can see here is that for growers who were using or are using double skip at the
moment pretty much what we’ve seen is that on average they’re sacrificing around 34%
of their yield potential in these high yielding seasons. Some of the sites it has been up
to 50%. In contrast, the single skip or the super
wide has on average been sacrificing 17%. Then the question really needs to be raised
then about how many people would want to go for this top-end yield potential, but also
considered how high risk it is. And I think that’s probably an important message is
that while this can look very attractive, it’s also extremely high risk, and so I
think really the area of interest is going to remain here, in this 1.5 metre row spacing.
And we’ve seen probably more growers and advisors shift to that in the last couple
of years, particularly because of the high yielding seasons, but also the 1.5 metre solid
offers you a much more even plant configuration across the paddock, compared to a skip where,
for example, the double skip you’re only planting half your paddock, and with a single
skip, obviously you’re still leaving large bare areas in your paddock to actually manage. Of course we wanted to look a bit at the economics,
and so Fiona Scott, who’s an economist with us at Tamworth has run most of our trial sets.
I just pulled out one of her graphs to pretty much illustrate one simple fact. With sorghum,
it’s all about yield. So if you want to make more money, you need to get higher yields,
and that’s basically the story over a range of different seasons. If we went to hybrid selection, just to look
at the genotype interactions here, what we’ve seen is that where we’ve used the low-tillering
hybrids, they have never been able to compete with the moderate or high-tillering hybrids
that we’ve included. So basically hybrids that have some level of tillering capacity
have been able to respond to the variable seasonal conditions that we’ve seen. And
so that compensatory mechanism is very important for us actually maintaining and trying to
actually achieve our top-end yield potential. So at this point in time, looking at the take
home messages from that project, what we’ve seen has been that the early planting for
sorghum in the western zone is still better than the late planting. And I haven’t included
that data today, but what we’ve seen is there’s been a yield benefit from the early
planting compared to the late planting, but also it’s just offered better rotational
fit for growers in that environment. So where growers are trying to get back into winter
crop pretty readily, that’s obviously an important factor. Late plant sorghum also
means that possibly you’ll have to dry the crop, and there’s a combination of basically
clashing of time for winter sowing and sorghum harvest. It’s important that you keep in
mind that on average, the yields have been about a tonne to the hectare higher than the
long-term average for this environment. So while I did say out loud last year that I
wanted some harder seasons, I probably didn’t quite really mean what we had last year at
Tulloona, but it would definitely be good to have some data from the lower yielding
end of the spectrum. But from the research that we’ve done to date, the yield has declined
as your effective row spacing has increased. So the solid plant outyields the single skip
and the super wide, which both outyield the double skip. If you are looking at your target plant populations,
we still think you should be targeting that 30,000 to 50,000; probably more reliably the
50,000 at this point in time. And I think continuing to select hybrids with a level
of tillering is always going to be an important mechanism for managing crop yields in our
environment. And finally as I’ve said, it’s all about yield so if we can improve the reliability
and improve the yield then it’s going to mean increased profits. To finish up, this work is funded under two
projects, as I’ve mentioned: sorghum in the western zone and the high yielding cereal
agronomy project. So I obviously need to acknowledge a range of different trial cooperators, growers
and many agronomists that have helped with site selection. Thanks to Pacific Seeds for
their continued support of the sorghum in the western zone project, and thanks to the
technical staff at Tamworth, who always help out with this.

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