GCTV15 Stubble Height Pt1
Narrator: Tony Crowley Stubble height trials could raise the bar
for southern grain yields.
Early outcomes from a joint Farmlink Research and CSIRO project into stubble height and
crop emergence indicate grain yields could be improved this harvest by setting the header's
cutter-bar higher.
Tony Pratt: Technical officer, Farmlink Research, Temora NSW
Yes that is correct we are finding that harvest height here in the southern region is having
impacts on grain yield at harvest time and it is also having some effects on crop emergence
in the following season.
Due to the high residue levels that we are getting in our crops here in the southern
region.
Narrator: The Downside trial just north of Wagga Wagga
is part of GRDC's national Stubble Initiative.
Chris Blanchard: Deputy Chair, GRDC Southern Panel
The projects that we're looking at are really specific for the particular growing areas
around the region that are impacted by issues with stubble retention.
Narrator: After a run of dry years the past few seasons
in the southern cropping region have been productive.
However here in this medium rainfall zone a good growing season can result in stubble
loads twice those of an equivalent yielding crop grown elsewhere.
Chris Minehan: Farm Consultant, Rural Management Strategies, Wagga Wagga NSW
So in southern NSW typically you'd be seeing between say 4 and 8 tonnes per hectare of
stubble and up to 10 tonnes in some years compared to probably 3 to 6 tonnes in northern
NSW but this is exacerbated by the year on year accumulation of stubble due to less summer
rainfall to break down between seasons.
Narrator: This layer of stubble and trash is up 50 millimetres
thick.
Last season's wheat yielded 2.8 tonnes to the hectare and where harvested low at approximately
15 centimetres, the stubble load was calculated to be 7.6 tonnes per hectare.
One of the trial's first findings has been that, that volume of material stopped some
grain from making it into the bin.
Tony Pratt: By harvesting lower you're having to take
a lot more of the crop biomass and residue and this has resulted in a .14 tonnes per
hectare lost of yield.
Just a sheer factor of the amount of residue going through the machine and not being able
to separate that grain.
We've also found that the speed of travel has been reduced with the lower harvest height
from 10.5 kilometres an hour back to 6.2 and this is having some effect on harvest efficiency.
Overall this has contributed towards a $64/ha loss by harvesting at a lower harvest height.
Narrator: It's a pretty significant finding.
The other major objective here is to measure the impact stubble management has on crop
emergence.
The wheat that preceded this canola was harvested either short or tall and the stubble managed
in one of four ways.
Tony Pratt: We have a short harvest height of around about
15 centimetres with the residue of the machine spread evenly across the harvest width.
We have a tall harvest height of around about 60 centimetres.
We have a tall harvest height with a burn associated with that and the burn was conducted
in Autumn or late March of this year.
And we also have a tall harvest height and a stubble treatment imposed on that which
was a K-line trash cutter.
Narrator: The canola went in in April, inter-row sown
into the stubble using a single disc seeder and spaced at 250 millimetres.
90 mills of rain fell in Autumn and now in Spring the differences in emergence are graphic.
Tony Pratt: This treatment here had a burn associated
with it, a tall harvest height and burn and we've got 30 plants per square metre in this
treatment.
In comparison the treatment we have just here is a short harvest height around about 15
centimetres and a spreading of that residue across the harvest width at harvest time.
You can really see that our plant numbers are back to around 15 plants per square metre.
Narrator: These were the two extremes.
But what about emergence in the other two treatments and what is the trail telling us
about machinery choice.
Find out in part 2 where you'll also get details on where to go for more information on the
Stubble Height and Crop emergence trial.
Ends