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Regions South Australia
(PIRSA) Senior Consultant Dr
Melissa Fraser led the project,
and said the trials were borne
from industry concerns that
the overuse of phosphorus was
compromising the economic
and environmental feasibility of
the industry.
Results from the trials
showed that more than 70
per cent of the sites had soil
phosphorus concentrations
sufficient to meet crop needs
with no additional phosphorus
fertiliser required.
“We found that the majority
of crops only need between
30-40kg of phosphorus applied,
based on removal rates, but
standard industry applications
were found to be 66-110kg/
ha. Reducing rates can lead
to cost savings of up to $250
per hectare based on current
fertiliser prices, which is
significant,” Dr Fraser said.
Mr Widdison said the
calibration of the DGT test for
potatoes will give producers
confidence in matching
phosphorus rate to soil type
and optimal yield.
“The major outcome
for producers is improved
economics, and by not
over-fertilising, unwanted
environmental impacts are
minimised,” he said.
Potatoes South Australia CEO
Robbie Davis said the project
was the first of its kind in
Anew test for measuring
phosphorus in the soil
is helping to deliver some
significant cost savings and
environmental benefits to
Australia’s potato industry.
The project, Innovative
Nutrient Management for the
Australian Potato Industry,
successfully proved that a new
test for measuring phosphorus
in the soil, the Diffusive
Gradients in Thin-films (DGT)
test, was more accurate at
predicting a yield response to
applied phosphorus fertiliser in
potatoes than currently used
soil tests. The project was a
joint initiative between Potatoes
South Australia Inc (the peak
industry association for the
potato value chain) and the
South Australian Government.
Fifteen replicated trials
investigating the applicability of
the DGT test in potato cropping
systems were conducted over
the past two years in South
Australia, including a trial at
Andrew Widdison’s property
located in the state’s south-east.
Mr Widdison grows potatoes
on 120 hectares of irrigated
country, across properties at
Kalangadoo and Mumbannar.
“The project gave a great
insight into the soil fertility of
our fields and the relationship
between phosphorus and our
soils,” Mr Widdison said.
“The results of the project
will give producers and their
advisers better information for
their decision-making in
fertiliser management.”
Primary Industries and
THE RESULTS FROM A SERIES OF TRIALS CONDUCTED IN
SOUTH AUSTRALIA WILL GIVE POTATO GROWERS AROUND
THE COUNTRY AN INSIGHT INTO THE RELATIONSHIP BETWEEN
SOIL PHOSPHORUS LEVELS AND YIELD, AS WELL AS THE MOST
EFFECTIVE METHOD TO MEASURE PHOSPHORUS IN THEIR SOILS.
New soil phosphorus test
shows promise for potatoes
Australia and a great example
of what could be achieved
when all members of the value
chain collaborate.
“The project has also created
a new network for the producers
involved and given them
greater access to soil scientists,
researchers, agronomists and
government extension staff and
each other,” Ms Davis said.
While the field trials had
been conducted only in South
Australia, the results and
critical DGT values are
relevant nationally.
“The extension of this
research across other soil types
and specific varietal trials at
a national level will greatly
assist in the quantification and
validation of these initial results.
This will also further enhance
the critical importance of the
application of the DGT test in
horticulture/agriculture as a
decision-making tool,” she said.
Innovative Nutrient
Management for the
Australian Potato Industry
was funded by the
Department of Agriculture
and Water Resources
National Landcare
Innovation. Details including
interpretation guidelines are
available at .
au or
This communication has
been funded by Horticulture
Innovation Australia Limited
using the Fresh Potato
Levy and funds from the
Australian Government.
Project Number: PT15007
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