KAROONDA
Karoonda broadacre farmers have a strong and proud history as innovative leaders in farm
management practices. New Horizons will work with these farmers to radically increase crop and
pasture production by tackling problems on poorly performing sandy soils.
New Horizons is an initiative to
capture an additional $1 billion in
food production per annum in South
Australia, support development of a
new high value manufacturing
industry in agricultural machinery,
increase long-term storage of soil
carbon and significantly reduce soil
erosion risk.
How will this be achieved?
Since the 1940’s, agronomic
research has focussed on
management of the top 10
centimetres of soil where most of
the plant roots are and where farm
machinery could most easily work.
However, increases in productivity
have slowed in recent times, with a
large proportion of the cropping
zone of South Australia not
reaching its potential.
In the Murray Darling Basin region
there are 947,000ha that could be
modified.
Initially, the New Horizons trials are
comparing modification treatments
on sandy soils in three South
Australian agricultural regions: the
Eyre Peninsula, the Murray Mallee
and the South East.
The trials are designed to better
understand which soil modifications
can improve productivity most
effectively.
Why are we doing this?
Broadacre agriculture is a
significant contributor to our State’s
GDP. Traditionally the sector has
been able to maintain a competitive
advantage because of the relatively
low cost of purchasing productive
land, labour and energy. However,
increasing input costs and volatile
commodity prices mean it is even
more important now to maximise
soil, water and nutrient efficiency.
Analysis conducted for New
Horizons suggests that up to 40%
of the broadacre farming area of
South Australia has soil constraints
that could be overcome.
Above: traditional tillage practices on the left and clay mixing on the right
Why Karoonda in the Murray
Mallee?
Compaction is being treated with a
spader.
The Karoonda site has been
selected as a typical sandy soil
found in the district. The site is flat
to gently undulating and has been
used for cropping (cereal and
canola) in rotation with legume
based pastures. The soil is a grey
shallow sand over a bleached white
sandy layer overlying a clay 3060cms below the soil surface.
Nutrient and water holding capacity
are being addressed by mixing clay
and organic matter (10 t/ha of
lucerne pellets) to a depth of 30
centimetres. The organic matter will
also stimulate microbial activity.
What are the key treatments at
Karoonda?
The treatments being compared at
this site are designed to address
the four major constraints thought to
affect these soils: non-wetting, poor
nutrient and water holding capacity
(particularly in the bleached layer),
infertiltity and compaction.
Additional nutrients to 30 cm aims
to overcome limitations to
production due to poor fertility in the
subsoil. This will ensure that there
is improved nutrition for crop root
development at all depths within the
modified soil profile.
The control is a well managed crop
using standard agronomic practices
for the area.
Results for farmers
All treatments had similar and
excellent emergence except
shallow incorporated clay that had
half the number of plants compared
to the control.
As this stage, plots that have been
modified have considerably more
crop growth than the control with
those that have had incorporated
organic matter appearing the best.
Treating water repellency has had
little impact on crop productivity so
far, but alleviating both compaction
and poor fertility have improved
crop growth at this stage.
Non-wetting is being addressed
through the addition of clay, spread
at an average rate of 620 t/ha
(‘actual clay rate of 150 t/ha).
Above: early results from the Karoonda trial site (control on the left and best treatment on the right)
www.pir.sa.gov.au/newhorizons
1300 364 322