In addition to the National Variety Trials, there's a variety specific agronomy packages
trial, growing time - variety response to sowing time experiments. And Guy's going to
talk about a couple of examples of those in a minute.
But what we have done is actually combine in the one analysis all of the NVT data with
all of the sowing time data and estimate variety response to sowing time. Now, that's available
on the NSW DPI website as a Primefact. The reason that we're doing that is pretty obviously,
there are varieties with a range of maturities we are recommending, and the Queensland and
the New South Wales crop sowing guides have got the varieties listed there in their sowing
window categories.
We're actually recommending a range of wheats from winter, facultative springs to early
springs, and they are gradually getting later in sowing. Now all that's a given.
But the issue is that there are a range of responses of varieties.
And those responses are actually presented in that Primefact as graphs of individual
varieties.
So Gregory, for example, is a flat response; Spitfire is better sown later than early,
relative to other varieties. If you can actually - you can actually use this information to
decide on what date you're actually going to change from one of the earlier sown varieties
to one of the - or winter or facultative varieties to one of the spring varieties.
By combining the data in some of those previous graphs all into the one graph, you can then
get a picture of what's happening. We've got Wedgetail winter maturity. It's actually much
better sown early than late. Spitfire, an early maturing spring variety: it's yields
decline after about year day 130, which happens to be about the 10th of May. So there's a
lot of action happening here at about the 10th of May, and that's about the time when
you would traditionally have shifted from the early maturing to the late maturing varieties
- sorry, the other way around - late maturing variety to early maturing variety. This actually
gives you a much more precise way of estimating when you would swap, and if you had two varieties,
for example, Wedgetail and Spitfire - Wedgetail for early sowing, Spitfire for later sowing
- it looks here like you would, in terms of their relative yield, you would be better
changing varieties at about the 10th of May as an appropriate thing to do. And so you
can use this to estimate the timing of that changeover. That's why we've estimated the
responses in that way.
So, as Peter said, we've been conducting a whole lot of agronomy work on new varieties
coming into the system, taking material that's coming out of AGT, LongReach, and trying to
really capture the key agronomic components that we need to consider in their management.
One of the key components of that trial program has been conducting a whole range of sowing
date experiments, to look at performance and maturity across a whole range of sowing times.
So from that, we're capturing information about yield responses, but also starting to
get a good databank around phenology and flowering date, and what's driving those different components
in the new varieties that are coming through. We've seen a lot of unusual results in the
last few years, particularly around Suntop and Lancer, and trying to understand that
day degree accumulation and how they flower. But what I'm going to do with the data today,
is look at the impact of getting that variety in its right sowing window, and what the impact
is, not just on yield, but also some rough agronomist's kind of gross margins, or just
gross returns.
So obviously, sowing date is all about balancing risk: risk of frost in a lot of environments,
but as we move into our western areas it becomes more about risk of heat. But it's getting
the balance. And it's in some of those environments where you can get a bit of both that you've
got some real decisions to make.
So we've taken a few trials. The first trial is from Trangie last year in an experiment
that was run by Greg Brooke, who's based there, on the 15th of April, the first sowing date.
And a couple of key things stand out: Eaglehawk, as Peter described in the first half of the
talk, is a facultative spring type, a long season, late flowering. And it has had about
a tonne to the hectare advantage over the other types, because of frost. The quicker
genotypes in there: the very quick ones, Dart and Spitfire, have had a massive impact of
frost in that environment. So pushing those genotypes into that earlier sowing window
has had a big impact on yield. Gregory, Lancer, Suntop, you can throw a blanket over them.
They've all performed pretty well, but getting that choice about Eaglehawk in the right window
as that type, has given a really big yield advantage. And that goes back to Simon Fritsch's
talk about attainable yields and managing varieties in the right sowing window to get
that attainable yield.
When we move to the second sowing date on the 29th of April, what you can see is there's
been a massive cost of sticking with Eaglehawk with a two-week delay in flowering - sowing
time. So it's pushing it out into that heat. So you're getting heat effects on that variety,
and Eaglehawk has dropped back by almost two tonnes to the hectare. Your main season wheats,
Gregory, Lancer, Suntop, maintaining their yield. And this is that critical point where
we start to get crossover to the next one. We're still seeing - we're seeing improved
performance out of the short season varieties.
And when we move to the last sowing date, that's where we really get that crossover
period that Peter was talking about in his talk. So that 10th of May, day 130 to 140
kind of sowing. What we're starting to see is a bit more of an advantage to start to
move to the short season types, but we're still getting pretty good responses out of
our main season varieties. They've got that flatline response across sowing dates, so
they're a lot more plastic in how they can perform. So you've moved from frost risk in
the early lines, through to heat risk at the end of that sowing window.
So when we have a look at the gross returns - so this is just the yield by the value of
the grain, using H1 at $248, APH at $276, as the prices were at delivered at Trangie,
you can see you're getting a massive difference.
So all I've presented here is the three types of wheat, an example of each. Eaglehawk as
the long season facultative; Gregory, which is - if I'd put in Suntop and Lancer it would
have been exactly the same line. It would have just overlapped. And similarly, Spitfire
at the end. What we can see is that decision to go with Eaglehawk on that first sowing
time, compared to a Spitfire, has been $509 to the hectare advantage of getting that right
genotype in that right sowing window. It's probably not the most sensible comparison,
because really if the choice can be coming down to do you sow Gregory in that early window
or the facultative type? And you've got almost or a bit over $200 to the hectare at that
end. And you can see the crossover period as we start to go out to that 14th of May.
At the other end of the spectrum, the decision to stick with Eaglehawk has yielded about
a $300 to the hectare difference in gross return, and about $100 to the hectare between
the Gregory versus the Spitfire type. So matching your variety to your sowing window, managing
the risk of heat and frost, is having a big impact in terms of your financial return and
getting that attainable yield. So in any season, that can account for a large proportion of
that yield gap that we've been hearing about most of the morning.
At Narrabri, a similar trial, I've only presented Eaglehawk, Gregory and Spitfire data. Obviously
a big impact of frost on Spitfire sown on the 23rd of April in that year. That sowing
time, if you think back to what we saw at Trangie, it's about two weeks later than at
the Trangie data, and we're not getting that advantage of that facultative week in that
window. So Gregory, and similarly Suntop and Lancer, performed about the same. So they
were all clustered together. As you push later though, you see there's some advantage in
moving to Spitfire even at that 12th of June, 4th of July sowing, compared to Gregory and
Eaglehawk.
The frost data for that site: thinking about that significant loss, there was a frost event
just prior to the start of flowering on those quick genotypes. So Dart and Spitfire commenced
flowering, and there was a period of minus 3 degrees in the screen at that site. And
that has been driving that risk of frost. At the other end of the season, that last
sowing time, which was pushed very late out into July, you're hitting heat risk. So they're
flowering right when our temperature is at - maximums are hitting over 30 degrees, and
quite high night temperatures as well.
So the gross returns, similar assumptions: $257 AH; $283 for Prime Hard delivered to
Narrabri. And they just mimic. Yield is king. It's all about the yield and driving those
differences.
So there has been a $200 loss about getting that choice right on that early sowing window,
and it's about the same. They're parallel lines with that Eaglehawk. Frost risk has
cost us about $400 per hectare at that site. So matching genotypes, getting your flowering
matched to that environment, is driving a significant component of those financial successes.
So in terms of the take home messages from Peter and myself, I suppose the variety response
data that Peter has been generating across a whole lot of multi-environment trials and
using BLUPs and lots of fancy acronyms. It really can be used to better match variety
to sowing date, and it can drive significant yield in those trials and those situations.
Sowing time and variety selection is all about risk: risk of a frost versus risk of heat.
So as we move into those western environments, heat is much more of a driver, and how it
interacts then with other things like crown rot and root lesion nematodes. So you have
to get that balance right between the two.
So the trial results show that there can be large economic outcomes, but risk is a moving
target. It varies from year to year because frost events vary from year to year. By being
too conservative in terms of frost - so by going too - and worrying too much about frost
can actually cost us just as much by pushing into the heat - the hot part of the sowing
window - flowering window, sorry.
So I suppose the solution is to either look at a range of varieties across sowing windows
or to stagger sowing it with one variety across different sowing windows to try to make sure
that you're optimising that risk profile.
I would like to thank GRDC for their support. I'd also like to thank New South Wales DPI
for their support for these trials. But obviously there's a lot people that would on these trials
in the background as well, and also the growers and the various research organisations that
allow us to run the trials on their property: Sydney University, and also the growers. Thank
you.