(COUNTRY MUSIC PLAYS)
NARRATOR:
little was known about the viability of pasture cropping
in Western Australia
due to the lack of local research and on-farm experience.
At this focus site south-west of Moora, staff from CSIRO
and the Department of Agriculture and Food Western Australia
are evaluating the viability of pasture cropping
across sub-tropical perennial grasses in WA.
The site was established in 2008
to collect detailed measurements on the soil water dynamics
and crop performance of different pasture-cropping systems.
At this site, we've grown barley in rotation with lupins
for the last four years.
Here's Wonga lupins sown into Gatton panic.
We're interested in exploring not only the logistics
of seeding a crop into a perennial,
but also how it performs in terms of yield.
Even though the period of active growth for the annual crop
and perennial pasture are at different times of the year,
there could be some overlap and competition
around the break of season and in spring.
The key thing we're doing at this site
is measuring the soil water uptake by the two different components.
So we've got the pasture and we've got the crop
and we want to know where in the soil
they're getting their water from
and what time of year they're doing it
so that we know how they're mixing it up together.
And one of the ways we're measuring soil water
is with these FDR probes.
They're about 30cm long and just go into the soil
and, yeah, you can program them
to measure soil water every 15 minutes.
And we put them in at different depths into the soil.
We can really look at day by day and hour by hour
where in the soil the different components are getting water from.
Soil moisture readings over time
have shown that the amount of stored moisture
under the annual crop and pasture cropping treatment differ.
Interestingly, the amount of stored moisture in the soil profile
during the winter growing season is similar.
By contrast, the amount
of soil moisture in summer
is about 100mm less
under pasture cropping
compared to the annual crop treatment,
down to a depth of 3m.
Greater depletion of soil moisture
under pasture cropping systems
occurs in summer, during the period
of active perennial growth.
This lifts groundcover,
provides green feed
and creates a larger 'bucket'
to reduce recharge after heavy rainfall events.
But what impact does this have on grain yield?
The key result we've got so far
is that over two years of growing crops and pastures together,
the crop yield has been much the same
whether we've had the pasture growing or not.
So we're not seeing anywhere near the yield penalty
that we thought we would.
For the past four years,
the performance of annual crop
sown over different perennial pastures
has been compared with an annual-based system.
All crops were sown after a knockdown,
sprayed with a broadleaf selective herbicide in-crop
and top-dressed with nitrogen at two different rates.
In 2009, barley sown in line with district practice
yielded 2.8 tonnes per hectare.
Grain yields were similar for crops sown over perennial grasses.
In subsequent years,
pasture cropping did not result in a yield penalty relative to the control.
The only significant yield penalty observed over three seasons
was in 2009, in treatments where 80 units of nitrogen
was applied to the barley crop.
In 2012, the lupin crop was reasonable
but there were some surprises.
One of the things that we did notice
was that the perennial grasses differed
in their tolerance to herbicides.
Here you'll notice that panic has come back after Verdict.
Contrast that with Rhodes grass,
which was impacted quite severely by the herbicide.
Many of the plants were actually killed,
but we're hoping that they'll come back through runners.
The value of this trial is in helping us parameterise a computer model
that will allow us to look at
how this farming system will operate on different soils,
in different regions, in different seasons.
Pasture cropping can be integrated into farming systems
from two perspectives - either as a grazing system,
in providing feed for stock out of season,
or it could be used as a cropping system
where grain could be harvested from the pasture-cropped paddock
in a favourable year.
To explore how widely this technology could be adopted,
we'll be using the trial to parameterise simulation models
and then use those simulation models
to help us predict where the pastures can grow,
where the crops can grow
and determine what seasons that we can get both crops and pastures
growing together.
Results from the Moora focus site
have confirmed that pasture cropping can be viable in WA,
but success is dependent on winter dormancy
or suppression in the perennial pasture,
effective weed control and adequate fertility and moisture.
The experiences of innovative growers
are highlighted in the third video of this series on pasture cropping
to show how growers are bringing all the pieces together.