BRENDON CANT brendon at iinet.net.au
Wed Sep 26 02:47:51 CEST 2007


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Garren Knell of ConsultAg and Alison Slade of the Department of Agriculture
and Food WA (DAFWA) and Corrigin Farm Improvement Group (CFIG), in a GRDC
funded study, trialled Precision Agriculture (PA) on Calingiri wheat at two
sites in WA last year.


Part of the GRDC PA initiative comprising 10 projects established in
2002-2003, it matched fertiliser inputs to productivity zones and yielded
variable results.


The GRDC has defined PA as ‘information-rich agriculture’ where the aim is
to increase profit and improve environmental management practises.


However, Mr Knell and Ms Slade concluded that it was not clear that variable
rate applications of fertiliser would generate significant profit compared
with blanket applications in the Corrigin district.


Over four years the trials consistently showed that the low and occasionally
medium input fertiliser treatments returned the highest gross margins. 


While the high input treatments often resulted in extra grain yield, the
additional fertiliser cost was not covered by the extra yield. The trials
were conducted in high and low yielding seasons.


Inconsistent performance of zones from year to year, due to yields varying
because of wet, dry or frost conditions, may have prevented zone treatments
achieving their full response.


Where soils had a high nutrition status (nitrogen, phosphorus, potassium and
sulphur) and low reactive iron, farmers could, in the short term,
significantly reduce fertiliser input and still achieve profitable grain


Mr Knell said the type of information gathered would allow farmers to better
understand their paddocks and crop fertiliser requirements and make
profitable fertiliser decisions.


The study investigated the practicalities of yield variability: was it
practical to control and economically useful to approach spatial variability
using PA?


Yield maps, other spatial information and input-control technology was used
to better match agronomy to paddock variability.


The results of two of the trial sites were presented at the recent GRDC
supported Controlled Traffic and Precision Agriculture Conference at the
University of Western Australia.


At the Corrigin site, wheat was sown in 2006 following wheat in the 2005
season. At Yotting, wheat followed lupins.


Paddocks were zoned using biomass imagery analysis developed by Silverfox.


A biomass stability map incorporated five seasons of crop performance to
identify zones that consistently showed poor, average or good performance.


Target yields for each productivity zone were based on biomass images and
farmer experience.


The Nulogic crop nutrition model determined the fertiliser required to
achieve target yield in each productivity zone. Air Agronomics assessed crop
biomass in response to the nutrition treatments.




The Crop Doctor is GRDC Managing Director, Peter Reading, Tel 02 6272 5525

Further Information: Garren Knell, Tel 08 9881 5551



GRDC REF: CDSept071.doc/CFIG2/Blumenthal

Brendon Cant & Associates
Public Relations & Marketing 
Suite 5
4 Gugeri St
Claremont WA 6010
Tel 08 9384 1122


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